Systematic Anatomy of Euphorbiaceae Subfamily Oldfieldioideae I. Overview

W. John Hayden

Pollen morphology is of great significance in taxonomy, phylogeny, palaeobotany, aeropalynology and pollen allergy (Paul E. et al.,2014). Nine (9) species of the family Euphorbiaceae (Cnidoscolus laurifolia, Croton zambesicus, Euphorbia heterophylla, E. hirta, Ricinus cummunis, Mallotus oppositifolius, Microdesmis puberula, Acalypha ciliata, and A. wilkesiana) were studied palynologically to determine the morphological features and diversity as an aid in the classification of its members. Pollen analytical studies of these species showed a lot of variations in the types of apertures, shapes, sexine pattern, pollen size, colpi length and width. However, the variations above are generally reduced within species of the same genera. For instance, E. hirta and E. heterophylla were observed to have tricolporate (C 3 P 3) aperture type giving reason for them being in the same genus. Similar form and symmetry observed in all the species studied also were reason for them being in the same family. INTRODUCTION A brief resumé of the history of comparative pollen morphology and taxonomy may enable one to understand better today's philosophy and practice of the subject. The study of pollen is inevitably linked with the history of microscopy but is also associated with fashion. Comparative pollen morphology has been studied for about 150 years beginning with workers like Mohl (1835) and Hassell (1842). The subject was adopted by workers in the classical German school of plant taxonomy of the late 19th and early 20th century as for example the works of Hallier (1893) on Convolvulaceae and Urban (1916) on Bignoniaceae show. Lately two workers have made outstanding contributions in providing the foundation for the study of pollen morphology in relation to systematics. First, Wodehouse (1935), who provided the classical background to the importance of the study of the "whole" pollen grain. A view almost forgotten by a majority of workers until comparatively recently where it has been so strongly advocated by Dahl (1976) and followed by Muller (1979, 1981) and is now rapidly becoming the accepted approach. The second great worker is of course Erdtman (1952) who provided the work which is rightly regarded as the corner stone of modern comparative pollen morphology. Erdtman's work centred on the study of the acid-resistant sporopollenin exine. The shape, size, apertures, ornamentation and the stratification of the wall are the characters which proved so useful in distinguishing pollen grains of different species genera, tribes, families and orders. Treatment with acids, the acetolysis method, arose from the techniques used to prepare fossil pollen from the Quaternary and earlier epochs.

University of Richmond UR Scholarship Repository Biology Faculty Publications Biology 1994 Systematic Anatomy of Euphorbiaceae Subfamily Oldfieldioideae I. Overview W. John Hayden University of Richmond, jhayden@richmond.edu Follow this and additional works at: http://scholarship.richmond.edu/biology-faculty-publications Part of the Botany Commons, Other Plant Sciences Commons, and the Plant Biology Commons Recommended Citation Hayden, W. John. "Systematic Anatomy of Euphorbiaceae Subfamily Oldfieldioideae I. Overview." Annals of the Missouri Botanical Garden 81, no. 2 (1994): 180-202. This Article is brought to you for free and open access by the Biology at UR Scholarship Repository. It has been accepted for inclusion in Biology Faculty Publications by an authorized administrator of UR Scholarship Repository. For more information, please contact scholarshiprepository@richmond.edu. SYSTEMATIC ANATOMY OF W.John Hayden2 EUPHORBIACEAE SUBFAMILY OLDFIELDIOIDEAE. I. OVERVIEW' ABSTRACT The biovulate subfamily Oldfieldioideaeof Euphorbiaceae, characterizedby spiny pollen, is an otherwise apparently diverse assemblage of mostly Southern Hemisphere trees and shrubs that traditionally have been allied with genera of Phyllanthoideae and Porantheroideae sensu Pax and Hoffmann. Although fairly diverse anatomically, the following structures characterize the subfamily with only a few exceptions: pinnate brochidodromousvenation with generally randomly organized tertiary and higher order venation; foliar and petiolar glands absent; unicellular or unbranched uniseriate trichomes; latex absent; mucilaginous epidermis or hypodermis; brachyparacytic stomata; vessel elements with simple perforation plates and alternate, often very small, intervascular pits; thick-wallednonseptate imperforate tracheary elements; numerous narrowheterocellularrays; and abundantaxial xylem parenchyma in diffuse to somewhat banded patterns and often bearing prismatic crystals. Anatomically, the shrubby Australian ericoid genera form a well-definedgroup with obvious affinitiesto the more arborescent Australasiangenera, which show clear relationships to each other; the African and neotropical genera bearing compoundleaves form another distinct group; the remaining genera are somewhat more isolated and seem to represent, in various cases, elements that are primitive within the subfamily or elements derived from the group bearing compound leaves. Presence of theoid teeth and palmately compound leaves in Oldfieldioideaeare features consistent with Dilleniid origin for Euphorbiaceae. As a taxonomic entity the euphorbiaceous subfamily Oldfieldioideae K6hler & Webster dates conceptually from the palynological studies of Punt (1962) and K6hler (1965) who noted the spiny pollen that characterizes the group; the assemblage recognized by pollen structure was subsequently formalized nomenclaturally as a new subfamily (Webster, 1967). In essence, pollen characters circumscribed a group of genera that previously had been assigned to the biovulate subfamilies Phyllanthoideae and Porantheroideae in the system of Pax & Hoffmann (1931). Webster's first (1975) classification of oldfieldioid genera contained several novel taxonomic associations at variance with earlier classifications, notably those of Pax & Hoffmann (1931) and Hutchinson (1969). Interest in the anatomy of Oldfieldioideae stemmed from the need for comparative data to aid placement of the problematic genus Picrodendron Planchon (Hayden, 1977). Despite a number of publications dealing with the anatomy of oldfieldioid genera (Appendix 2), detailed information for most of the subfamily is lacking. Once Picro- dendron was shown to be a member of Oldfieldioideae (Hayden, 1977; see also Hayden et al., 1984, and Hakki, 1985), an anatomical survey of the entire subfamily was initiated (Hayden, 1980) to assess relationships from data independent of reproductive (includingpollen) morphology. Based in part on these anatomical studies, classification of Oldfieldioideaehas been modified from Webster's (1975) original proposal; two broadly similar classifications, one by G. L. Webster (the preceding issue) and another by G. A. Levin and M. G. Simpson (this issue), are proposed elsewhere. HISTORY Classifications of Euphorbiaceae from the first half of the 19th century (e.g., Jussieu, 1824; Endlicher, 1836-1840) offer little insight into relationships among oldfieldioid genera. At this formative time in the definition of Euphorbiaceae (Webster, 1987) the few oldfieldioidgenera known were often scattered widely in the family; moreover, some were referred to other families. Genera ' This study is based largely on a Ph.D. dissertation submitted to the University of Maryland, College Park. I thank W. L. Stern for assistance and guidance; H. K. Airy Shaw, L. J. Hickey, G. A. Levin, A. M. W. Mennega, and G. L. Webster were particularly helpful in providing specimens and/or comments; numerous others also provided specimens. 2 Department of Biology, University of Richmond, Richmond, Virginia 23173, U.S.A. ANN. MISSOURIBOT. GARD. 81: 180-202. 1994. Volume 81, Number 2 Hayden 1994 EuphorbiaceaeSubfamilyOldfieldioideae of Pseudanthinae (or Caletieae in the traditional/ narrow sense) were the first to be classified together, undoubtedlybecause of their shared ericoid xeromorphic habit and common provenance in Australia. Baillon (1858) grouped Micrantheum Desf. with Pseudanthus Sieber ex Sprengel, to which Agardh (1858) added Stachystemon Planchon, establishingthe composition of Caletieae that was followed in all subsequent studies until the addition, first, of Neoroepera Muell. Arg. by Kohler (1965) and, now, the inclusion of all Australasian oldfieldioidsas proposed by Levin & Simpson (1994, this issue) and Webster (1994). During the intervening years, however, the use of cotyledon width as the primary criterion for subdivision of the family (Mueller, 1866; Pax, 1890; Pax & Hoffmann, 1931) relegated the genera of Pseudanthinae (as Caletieae) to the Stenolobeae, a small group of Australian xerophytes with narrow cotyledons. Their somewhat isolated position in Stenolobeae minimizedassociationof Pseudanthinaewith other oldfieldioidgenera. Other oldfieldioidgenera similarly suffered early taxonomic assignments that delayed consideration of relationshipswith the rest of the subfamily. Baillon (1858) submerged Podocalyx Klotzsch within the phyllanthoidgenus Richeria Vahl, a disposition followed well into this century. Oldfieldia Benth. & Hook. f. was temporarily considered sapindaceous (Mueller, 1866; Baillon, 1878). Worse, the relationships of Picrodendron were long obscured by a series of misassignments at both the generic and familial levels (Hayden et al., 1984). Aside from Caletieae sensu stricto, the genera of Oldfieldioideaewere scattered widely in Mueller's (1866) treatment of the family for the Prodromus; Mischodon Thwaites was included with uniovulate genera, following an earlier error of Baillon (1858), Oldfieldia was still banished to Sapindaceae, and the remaining five oldfieldioid genera in his treatment were each assigned to different subtribes of Phyllantheae. Greater cohesiveness is apparent in a later publicationof Baillon (1878). For example: Choriceras Baillon was included within Caletieae;Austrobuxus Miq. (as Buraeavia Baill.), Longetia Baillon ex Muell. Arg., Petalostigma F. Muell., and Hyaenanche Lambert formed a sequence; and Dissiliaria F. Muell. ex Baill. followed Richeria (which included the oldfieldioidPodocalyx). (See Webster (1987) for commentary on Baillon's peculiar "serial" system to indicate relationships.) Additional elements were gradually accreted to this loosely defined nucleus of oldfieldioidgenera. Bentham (1880), in his treatment of Euphorbiaceae in the Genera Plantarum, 181 included, using current nomenclature, Dissiliaria, Longetia, Austrobuxus, Hyaenanche, Mischodon, Oldfieldia, Piranhea Baillon, and only one nonoldfieldioidgenus, Bischofia Blume, within genera 46-54. Although these plants constituted three discrete groups in his conspectus, Bentham (1878) expressed some doubt about their relatedness and he chose to associate Neoroepera and Petalostigma with other phyllanthoid genera. Pax (1890) treated oldfieldioidgenera much as had Bentham; Tetracoccus Engelm. ex C. Parry, however, was included, and Pax & Hoffmann (1931) added Petalostigma, Androstachys Prain, and Aristogeitonia Prain to various subtribes consisting largely of oldfieldioid genera. Perhaps the first clear indication of the relatedness of oldfieldioid genera can be found in Pax's (1925) essay on Euphorbiaceae, which includes the phylogenetic tree reproduced in Figure 1. Although much of the detail in this phylogenetic tree may be challenged seriously in the light of present knowledge, it does show oldfieldioid genera (as usual, minus Pseudanthinae) comprising a clade distinct from other biovulate Euphorbiaceae. In the dispositionof genera, Hurusawa's (1954) classification of Euphorbiaceae essentially follows that of Pax & Hoffmann (1931) and thus contains no new insights on classification of oldfieldioidgenera. In light of Pax's (1925) phylogeny and because of its disregard for the palynological data available at the time (Punt, 1962; K6hler, 1965), Hutchinson's (1969) classification was a retrograde development; oldfieldioidgenera were widely distributed in five of 12 biovulate tribes, with three tribes mixing oldfieldioid and phyllanthoid elements. Hutchinson was the first, however, to associate Paradrypetes Kuhlm. with other oldfieldioidgenera. Airy Shaw (1965) entertained serious doubts about inclusion of several oldfieldioid genera in Euphorbiaceae. Accordingly, he proposed Androstachydaceae, of uncertain relationships,to accommodate Androstachys; he recognized Picrodendraceae as distinctfrom but alliedto Euphorbiaceae; and he viewed Aristogeitonia, Calaenodendron Standley, Mischodon, Oldfieldia, and Piranhea as occupying an intermediatepositionbetween these families (Airy Shaw, 1966, 1972, 1973). Airy Shaw (1983) continued to accept an isolated taxonomic position for Stenolobeae (including Pseudanthinae), but he did, consistently, group the remaining Australasian genera of Oldfieldioideae in adjacent tribes in several of his informalor tentative classification systems (e.g., Airy Shaw, 1975, 1980b, 1983). 182 Annals of the Missouri Botanical Garden WI ELAND IINAE ANDRACHNINAE PS EUDOL ACH NOSTYLI DINAE PETALOSTIGMATINAE Petalostigma ANTI DESM INAE AMANOINAE DRYPETINAE Drypetes DISCOCARPINAE UAPACI NAE Heywoodia Lingelsheimia Neoroepera Tetracoccus BISOHOFFIINAE SAUROPODINAE/ PHYLLANTHINAE PAIVAEUSINAE Aristogeitonia Old fieldia Piranhea TOXICODENDRINAE Androstachys Hyaenanche GLOCHIDIINAE DISSILIA RIINAE Dissiliaria Longetia (incl. Austrobuxus) Mischodon FIGURE 1. Relationshipsof subtribes of Phyllantheae, after Pax (1925). Right-hand clade is the earliest published phylogram of Oldfieldioideae.Generic composition of subtribes, where indicated, follows Pax & Hoffmann (1931); oldfieldioidtaxa are in bold italics. Other than Pseudantheae, Podocalyx (treated as a subgenus of Richeria [Antidesminae]) is the only element of Oldfieldioideaeknown to Pax and not included in the phylogram. DESCRIPTION, CIRCUMSCRIPTION,AND DISTRIBUTION of two to five carpels; styles are generally undiPlants of Oldfieldioideaeare woody, ranging from vided; each locule houses a pair of pendulous anatlow depressed shrubs to tall trees. Latex is absent ropous ovules. Seeds are often carunculate and and vestiture consists of unicellular or uniseriate usually possess copious endosperm. Reports of n trichomes.Leaves are alternate,opposite,or whorled = 12 for Pseudanthus (Hassall, 1976), 2n = 48 *andmay be simple or palmately compound;petiolar for Picrodendron (Fritsch, 1972), n = 24 for and laminar glands are absent; stipules may be Mischodon and Tetracoccus (Hans, 1973), and n present or absent. Leaves may be strongly reduced = 24, 2n = 48 for Mischodon (Sarkar & Datta, in xerophytic species. Plants are typically dioe- 1980) collectively suggest a base number of x = cious. Flowers are apetalous, and most lack discs. 12 for the subfamily. Stamens range from three to many. Pollen is biThe first comprehensive classification of Oldnucleate, with four to many brevicolporate to po- fieldioideae (Webster, 1975) included 21 genera, rorate apertures; the exine lacks a foot layer, bears but several changes in composition have occurred a discontinuous interstitium and thick perforate since then. Two newly discovered genera, Voatatectum with prominent supratectal spines (Levin malo Capuron ex Bosser (1976) and Whyanbeelia & Simpson, 1994, this volume). Gynoecia consist Airy Shaw & B. Hyland (Airy Shaw, 1976), have Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae been referred to the subfamily. Two enigmatic genera, Croizatia Steyerm. (Webster et al., 1987) and Paradrypetes (Levin, 1992), have been assigned to Oldfieldioideaefollowing discovery of diagnostic flowering material and, especially, after study of pollen from these plants. Kairothamnus Airy Shaw (1980a) and Scagea McPherson (1985) have been segregated from Austrobuxus sensu lato, as has Canaca Guillaumin, if only tentatively (Webster, 1994). In recent years Radcliffe-Smith has redefined generic limits for several Oldfieldioideae. He has included Paragelonium Leandriwithin Aristogeitonia (Radcliffe-Smith, 1988), he segregated Stachyandra R. -Sm. from Androstachys to accommodate several Madagascan species bearing compound leaves (Radcliffe-Smith, 1990), and he expanded Pseudanthus to include Stachystemon (Radcliffe-Smith, 1993). The number of genera now stands at 27. (Solely because of the recency of its reclassification,Stachystemon is herein treated as a distinct genus.) Genera of Oldfieldioideaeare mostly mono- or oligotypic. Austrobuxus, with perhaps 20 species, is the most speciose, followedby Pseudanthus (seven species) and Petalostigma (six species). The total number of species referable to the subfamily is estimated at 86, approximately 1 percent of the total number of species in Euphorbiaceae. Oldfieldioideaeis largely a southern hemisphere group. Only three genera occur in areas not derived from the breakup of Gondwanaland;these are Celaenodendron, from western Mexico, Picrodendron, from the Bahamas and Greater Antilles, and Tetracoccus from Mexico and the southwest United States. Eight genera and 16 species occur in the New World, six genera and 16 species occur in Africa and Madagascar, one monotypic genus occurs in southern India and Sri Lanka, and 13 genera and 52 species are Australasian. No genus of Oldfieldioideaehas a bicontinental distribution, although Androstachys and Aristogeitonia occur both in Madagascar and Africa. cations listed in Appendix 2 has been incorporated into the following account as appropriate. MATERIALS This report is based on first-hand examination of 97 leaf and 87 wood specimens of 61 species of Oldfieldioideae. Specimens examined are listed in Appendix 1. The specimens available represent to some degree all genera of the subfamily except Croizatia and Paradrypetes; it should be noted that leaves of Voatamalo and wood of Kairothamnus, Scagea, and Stachystemon are lacking in this study. Previous anatomical literature concerning genera of Oldfieldioideae provided by the publi- 183 LEAF ARCHITECTURE For the most part, leaves are either simple or palmately compound; however, interesting transitional morphologies do exist. Leaves of Oldfieldia are palmately compound, with 3-8 leaflets; those of Celaenodendron, Picrodendron, and Piranhea are trifoliolate;both palmately compound and simple leaves occur in Aristogeitonia; and leaves of Parodiodendron Hunz. are unifolioate, as evidenced by the minute stipelsat the apex of the petiole (Hunziker, 1969) and by the frequent disarticulation of the lamina at the same point (Fig. 4). Finally, leaves of Micrantheum, which occur in alternate groups of three (to five), have been interpreted as the leaflets of a palmately compound leaf which, by loss of their common petiole, are sessile on the stem (Baillon, 1858); alternatively, this unique phyllotaxy has been attributedto foliate stipules (Griining, 1913; Webster & Miller, 1963). For the most part, leaf margins are entire, the few exceptional species being Austrobuxus cuneatus (Airy Shaw) Airy Shaw, A. swainii (de Beuzev. & C. T. White) Airy Shaw, Choriceras tricorne (Benth.) Airy Shaw (Figs. 7, 8), Dissiliaria muelleri (Baill.) ex Benth., Paradrypetes ilicifolia Kuhlm. (Levin, 1986), P. subintegrifolia G. Levin (Levin, 1992), Tetracoccus dioicus Parry (only some leaves), and T. ilicifolius Coville & Gilman. Paradrypetes possesses irregularly spaced spinose teeth (Levin, 1986, 1992). Teeth of Tetracoccus ilicifolius are the largest in the subfamily: median veins of these teeth are derived from the looped secondary veins; there are prominent brochidodromouslikeloops within the tooth itself; and median veins extend nearly to the apices, which in the specimens examined appear to possess apical caps, at least in young leaves. Teeth of the remaining species are much smaller, consisting of a vein ending in a small protrusionof leaf tissue. Significantly, however, deciduous apical caps are also visible in Austrobuxus swainii and Choriceras tricorne (Figs. 7, 8). Tooth morphology in Oldfieldioideae thus conforms with the theoid type (Hickey & Wolfe, 1975). Excluding noninformative spinose teeth, theoid teeth are the only type found in Phyllanthoideae, specifically in the genera Drypetes Vahl, Putranjiva Wall., and Bischofia; reduced theoid teeth are also present in Aporuseae (Levin, 1986). Venation is always pinnate, most frequently festooned brochidodromous(Figs. 2, 3). In addition to brochidodromy, however, leaves of Longetia Annals of the Missouri Botanical Garden 184 Si n~~~S S NEW MMW !v AW EW x~~~~~~~~~~~~5 2. Austrobuxus ofOldfieldioideae. (Baumann-Bodenheim features architectural FIGURES2-8. Leaf rubiginosus mexicanum (Ortega6367), clearedleaf,bar= 1 cm.15010),clearedleaf,bar= 1 cm.-3. Celaenodendron of petiolefrombaseof lamina, 4. Parodiodendron (Hueek469), clearedleaf,notedisarticulation marginivillosum bar= 2.5 baccatum(Gillis6963), notelackof veinordersbeyondtertiaries, bar= 5 mm.-5. Picrodendron 185 Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae exhibit a tendency toward eucamptodromy whereas Picrodendron (Fig. 5), and Piranhea (all New World genera with trifoliolate leaves) plus Androstachys; this character state is extremely rare in the dicots as a whole (L. J. Hickey, pers. comm.) and is thus a potentially robust synapomorphylinking these genera. Areoles are well developed in the genera with compound leaves (Figs. 5, 12) plus Dissiliaria, Mischodon, Parodiodendron (Fig. 6), and Podocalyx; otherwise, areoles are imperfectly developed. Areoles are usually arranged randomly, but are oriented in Celaenodendron and somewhat oriented in Picrodendron, Piranhea, and Dissiliaria. Veinlets are usually present and mostly simple or branched; the degree of branching varies widely, tending to be most highly branched in leaves with low regularity of tertiary and higher order veins. Veinlets are absent in Androstachys (Fig. 12), but they may appear to be present upon superficial examination because of the columnar sclereids located in each areole (see below). those of Dissiliaria, Petalostigma, Picrodendron, and Tetracoccus tend toward reticulodromy. Leaves of the Australian genera of Pseudanthinae (Caletieae sensu stricto) exhibit a continuum of increasing disorganization, presumably a consequence of xeromorphy: in Neoreopera leaves are weakly festooned brochidrodromous; in Micrantheum one can find vestiges of brochidodromous venation as well as secondary veins that recurve and ramify or form a weak reticulum; in Stachystemon the range is from reticulodromous to kladodromous; and in Pseudanthus leaves are all kladodromous (Fig. 9). Primary veins are mostly of moderate size, but, especially in xeromorphic leaves, they may range to stout and massive, e.g., those of Hyaenanche, Tetracoccus, and the Australian Pseudanthinae (Fig. 9). Intersecondary veins are usually absent, although one or two simple intersecondaries per intercostal area occur occasionally in Austrobuxus and Mischodon, and routinely in Croizatia (Levin, 1986), Oldfieldia, Paradrypetes (Levin, 1986), Piranhea, and Podocalyx. Intersecondary veins are frequent in several primitive Phyllanthoideae, namely, Amanoa Aubl., Blotia Leandri, Heywoodia Sim, Petalodiscus Baill., Savia Willd., and Wielandia Baill. (Levin, 1986); their presence is thus postulated to be primitive for Oldfieldioideae. Tertiary vein patterns are usually random reticulate; ramified patterns occur in Hyaenanche, species of Austrobuxus, and those species of Australian Pseudanthinae that possess distinguishable tertiaries; there is a slight tendency toward transverse tertiaries in Parodiodendron, Paradrypetes (Levin, 1986), Petalostigma, and Podocalyx; and the tertiary veins of Piranhea have a slight tendency to form orthogonal patterns. Marginal venation is incomplete (Fig. I 1) or looped (Fig. 6) in many genera, "hemmed" with a fimbrial vein in the genera with compound leaves (Figs. 10, 12) plus Dissiliaria and Mischodon, or dominated by a massive intramarginal vein in most Australian Pseudanthinae (Fig. 9). A distinctive furcate-flabellate form of marginal venation occurs in Hyae- nanche. High-order venation varies considerably within Oldfieldioideae. Perhaps most notable is the occurrence of ultimate reticula in which vein order is not distinguishable, a feature of Celaenodendron, LEAF ANATOMY Trichomes have been observed in about twothirds of the genera of Oldfieldioideae.Many species are glabrescent with age, although mature leaves of Androstachys, Parodiodendron, and species of Petalostigma, for example, are clearly pubescent. Trichomes are either simple unicellular or uniseriate, generally consisting of less than six cells. Within Pseudanthinae, epidermal emergences range from small papillae to four-celled uniseriate trichomes. The densely packed trichomes of Androstachys johnsonii Prain, which consist of a short basal cell and long curly terminal cell, have been suggested by Alvin (1987) to function in absorption of atmospheric moisture (mists and drizzles) in the otherwise extremely arid environment of southern Africa. Oldfieldia possesses trichomes similar to those of Androstachys, arguing for some degree of relationshipbetween these two genera despite their manifest differences in reproductive morphology. Depending on the species, trichomes of Austrobuxus are either simple or bifurcate (malpighiaceous). Parodiodendron is unique within the subfamily in possessing strongly ciliate leaf margins (Fig. 6). Rao & Raju (1985) reported uniseriate, stellate, and glandular hairs in Dissiliaria, characteristics reminiscent of uniovu- mm.-6. Parodiodendron marginivillosum (Hueck 469), margin of cleared leaf, bar = 250 ,um.-7. Choriceras tricorne (Forman s.n.), tooth at margin of cleared leaf, bar = 250 ,um.-8. Choriceras tricorne (Forman s.n.), paradermal section through tooth at leaf margin, note glandular apex, bar = 100 ,um. Annals of the Missouri Botanical Garden 186 K~~~~~~~~~~~~~~~~~~~~~~~~~ $k17 Leaf architecture of Oldfieldioideae.-9. Pseudanthus orientalis (Clemens 44092), kladodromous FIGURES 9-12. Celaenodendron mexicanum (Ortega venation, massive primary and intramarginal veins, bar = 250 gm.-10. 6367), fimbrial vein (far right), bar = 250 ,um.-11. Petalostigma banksii (Perry 1981), branched veinlets with swollen ultimate tracheids, bar = 100 m. -12. Androstachys johnsonii (Wellcome Chemical Research Laboratory s.n.), well-developed areoles with columnar sclereids, veinlets absent, bar = 1 mm. late euphorbs that would be unique to Oldfieldioideae; however, neither trichomes nor their bases were detected in the leaves available to me. The epidermis is fundamentally uniseriate. However, a single layer of hypodermis has been reported for Paradrypetes (Milanez, 1935) and some or all epidermal cells of the Australasian genera have a horizontal partition resulting in a poorly to well-defined hypodermis (Figs. 17-19). The inner cell or chamber thus formed contains mucilage, which is common in other genera as well. Expansion of the mucilaginous layer in Australian Pseudanthinae greatly distends the adaxial epidermis (Figs. 18, 19); while the grossly expanded mucilaginous layer may well be an artifact of preparation, it is derived solely from the lower portions of subdivided epidermal cells and is not thickly multicellular as depicted by Gaucher (1902), whose erroneous in- Volume81, Number2 1994 Hayden 187 EuphorbiaceaeSubfamilyOldfieldioideae TB *;i.~~~~~~~~~~0 W T4P FIGURES13-16. Leaf anatomyof Oldfieldioideae.-13. Longetia buxoides(Baumann-Bodenheim 5605), stomate from cross section,bar = 20 sum.-14. Scagea oligostemon(McKee2352), surfaceview of stomatefrom paradermal section,note crenulateinneranticlinalwallsof subsidiarycells visiblethroughstomatalaperture,bar = 10 Mm.-15. Austrobuxushuerlimannii(McKee4850), subdividedcrenulatesubsidiarycells and trichomebases from paradermalsection, bar = 20 Mum.-16.Podocalyx loranthoides(Krukoff811), tracheoididioblastsfrom maceratedmesophyll,bar = 20 ,um.GC = guardcell, SC = subsidiarycell, TB = trichomebase. terpretation has been reiterated by others (e.g., Metcalfe & Chalk, 1950; Raju & Rao, 1977). So far, no mucilage has been detected in Aristogeitonia, Celaenodendron, Mischodon, Piranhea, and Podocalyx. Mucilaginous epidermis is known in several Phyllanthoideae, for example, Actephila Bl., Antidesma L., Aporusa Bl., Amanoa, Baccaurea Lour., Bridelia Willd., Hyeronima Fr. Al- lem, Phyllanthus L., Richeria, and Savia (Metcalfe & Chalk, 1950). In surface view, anticlinal walls of epidermal cells are generally straight (Figs. 14, 15), the only exceptions being Aristogeitonia, Celaenodendron, Piranhea, (all members of Picrodendreae), and Dissiliaria, in which these walls have a wavy outline; intriguingly, paradermal sections of Aristogeitonia and Celaenodendron reveal Annals of the Missouri Botanical Garden 188 PF _M) PF - (M) -17. Longetia buxoides(BaumannFIGURES17-21. Leaf anatomyand woodparenchymaof Oldfieldioideae. -18. Pseudanthus Bodenheim5605), leafcrosssection,notechamberedmucilaginous epidermalcells,bar= 100 Aum. orientalis(Wilson 679), leaf cross section, note grosslyexpandedmucilaginoushypodermisand prominentintramarginalveins, bar = 100 um.- 19. Micrantheumhexandrum(McGillivray3196), crosssectionof primaryvein, note grosslyexpandedmucilaginoushypodermis,bar = 100 um.-20. Hyaenancheglobosa (GodfreySH 1257), cross sectionof leaf, bar = 100 ,um.-21. Piranhea trifoliata(Duckes.n., USw 31485), normaland chambered axialxylemparenchymacells, bar = 15 Am.PF = phloemfibers. crystalliferous 189 Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae the inner portions of epidermal cells to possess straight anticlinal walls. Leaves are overwhelmingly hypostomatic, although both hypo- and amphistomatic conditions occur in species of Petalostigma and Tetracoccus. Stomatal type is anomocytic in Podocalyx, paracytic in Paradrypetes (Levin, 1986), but otherwise brachyparacytic (Fig. 14) or derived from a brachyparacytic pattern. For example, intruding lobes of adjacent cells tend to form an anomocytic pattern in Tetracoccus as viewed from the surface; paradermal sections, however, reveal typical brachyparacytic configurations.The most frequent modification of stomatal type is the tendency for one or both of the subsidiary cells to become subdivided into two or three smaller cells; subdivision of subsidiary cells may be a consistent feature in a given taxon, or it may be sporadic, affecting only some stomata or only one subsidiary cell of a given pair. Subdividedbrachyparacytic stomata occur in Androstachys, where the pattern has been described as incompletely cyclocytic (Alvin, 1987), Aristogeitonia, some species of Austrobuxus (Fig. 15), Hyaenanche, Mischodon, Picrodendron, and Pseudanthus. The paracytic stomata of Paradrypetes are also subdividedin a similarfashion (Levin, 1986). The distribution of subdivided subsidiary cells does not follow any obvious taxonomic grouping within the subfamily. Within Phyllanthoideae, brachyparacytic stomata are characteristic of Bridelieae, Drypeteae, Phyllantheae-Fleuggeinae, and certain genera of Wielandieae; moreover, subdivided brachyparacytic stomata occur in Lachnostylis Turcz. and Bridelia (Levin, 1986). Raju & Rao (1977) reported brachyparacytic stomata to be the most common type among woody genera throughout Euphorbiaceae. In most genera subsidiary cells extend partially over the inner periclinal walls of adjacent guard cells in a "semi-piggyback" fashion (Fig. 13); the inner anticlinal walls of subsidiary cells thus delimit an inward extension of the stomatal pore. Within Phyllanthoideae, Levin (1986) noted a similar spatial relationship of guard and subsidiary cells only in Drypetes. The inner anticlinal walls of "piggyback" subsidiary cells may have crenulate outlines (Figs. 14, 15), a feature first observed by Solereder (1908) in Micrantheum and Pseudanthus that now proves characteristic of the Australasian genera (Mischodon and certain species of Austrobuxus excluded) plus the South African genus Hyaenanche; this feature defines a distinct clade within the subfamily. Crenulate subsidiary cells are only weakly developed in the single specimen of T;hyanbeelia available for study. In con- trast to most genera, subsidiary and guard cells are coplanar in Oldfieldia and Parodiodendron. Mesophyll is bilateral except in some species of Petalostigma with isobilateral leaves; leaves of Hyaenanche approachan isobilateralcondition(Fig. 20). Spongy mesophyll with well-developed intercellular spaces but a tendency towardvertical alignment of cells occurs in Androstachys, Oldfieldia, Picrodendron, and Piranhea, all members of Picrodendreae. Mesophyll usually contains scattered druses; prismatic crystals are also present in Aristogeitonia, Austrobuxus, Dissiliaria, Hyaenanche, Longetia, and Micrantheum. Mesophyll of Paradrypetes contains raphide bundles (Milanez, 1935; Levin, 1986), a structure otherwise unknown in Euphorbiaceae(Gaucher, 1902; Metcalfe & Chalk, 1950). No crystals were observed in the mesophyll of Celaenodendron, Parodiodendron, and Piranhea. Except for Androstachys and Stachyandra, foliar sclereids are absent; areoles of these genera usually contain a single columnar sclereid with ramified tips that run parallel with the bases of epidermal cells and eventually intermingle with trichome bases and the bundle sheath extensions of the veins. Alvin (1987) has interpreted the sclereids of Androstachys to function in apoplastic transport from its water-absorbant trichomes. It is intriguing to speculate that the vertically oriented spongy mesophyll cells of Androstachys may have served as a preadaptation for the evolution of its columnar sclereids. Another unique mesophyll feature is found in Podocalyx, which bears unbranched, sinuous tracheoid idioblasts with spirallythickened, nonlignifiedwalls (Fig. 16). These elements, occurring most frequently between the junction of palisade and spongy layers, are sufficiently abundant to obscure the presence of veinlets in clearings; they are not, however, directly connected to any vasculature. Vasculature of the primary vein consists of adjacent (colateral) regions of xylem, phloem, and phloem fibers. Little taxonomic significance can be read into the overall configuration of primary vein vasculature, which ranges from broad shallow arcs to more tightly curved u-shaped arcs to closed loops; reduced leaves of desert xerophytes, however, tend to have patterns with minimal curvature (Figs. 18, 19). Phloem fibers of the primary vein in Petalostigma and the Australian Pseudanthinae are unlignified (Figs. 18, 19), in sharp contrast to the usual lignified condition of these cells in the rest of the subfamily. Smaller veins are frequently associated with a parenchymatous bundle sheath (Fig. 17). Bundle sheath extensions that are merely parenchymatous occur in Longetia (Fig. 17); crys- 190 Annals of the Missouri Botanical Garden tals are present in bundle sheath extensions of Aristogeitonia, Celaenodendron, Hyaenanche, Mischodon, Oldfieldia, Parodiodendron, Petalostigma, Picrodendron, and Piranhea; and at least some fibrouselements are also present in those of Androstachys, Mischodon, and Piranhea. Overall, bundle sheath extensions seem best developed in the genera bearing compound leaves, but also occur sporadically elsewhere in the subfamily. Swollen terminal tracheids of veinlets occur in some Austrobuxus, Choriceras, Hyaenanche, Longetia, Petalostigma (Fig. 11), and Tetracoccus. to reticulate). Tyloses and/or tannins are common in lumina of heartwoodvessels; silica deposits occur in lumina of Whyanbeelia. Imperforate tracheary elements bear either simple or borderedpits. Elements with simple pits, i.e., libriformwood fibers, characterize the genera with compound leaves (Aristogeitonia, Celaenodendron, Oldfieldia, Piranhea, and Picrodendron) plus Dissiliaria, Hyaenanche, and Petalostigma; some of these may also possess elements with bordered pits. The remaining genera possess only elements with bordered pits; these cells are probably best characterized as fiber-tracheids by virtue of their relatively small pit borders and thick walls. However, because intervascular pits in some oldfieldioidsare remarkably small, Androstachys, Aristogeitonia, and the Australian genera of Pseudanthinae, for example, pits of imperforate elements may be approximately equal to or slightly larger than intervascular pits in the same wood; by the criteria of Bailey (1936) such elements would be tracheids, by definition, despite their thick walls and pit diameters of 5 gim or less. "Tracheid," with its connotation of primitive conducting element, hardly seems appropriate for such cells. On the other hand, the tracheids of Podocalyx, with pit diameters up to 13 tm, attest more convincingly to primitive structure, and both fiber-tracheidsand tracheids are present in Austrobuxus, distinguishable by both wall thickness (Fig. 22) and pit size. Bands of gelatinous fibers occur in woods of Australian Pseudanthinae (Fig. 24), Hyaenanche, and Tetracoccus. Imperforate elements often possess such thick cell walls that lumina appear completely closed; Bamber(1974) noted that these thick-walled fibers lack an easily detectable S3 layer in Austrobuxus, Dissiliaria, and Petalostigma. Fibers are septate only in Parodiodendron. Rays are numerous, generally more than 15 per mm; however, there are more than 20 per mm in Australian Pseudanthinae, and only 12 per mm in Androstachys and Oldfieldia. High ray frequencies are probablyrelated to the general narrowness of individual rays. Rays are mostly 1-, 2-, or 3-seriate, but up to 4- or 5-seriate rays occur in Choriceras, Dissiliaria, Aristogeitonia, and Tetracoccus (Fig. 33). Polymerous (vertically fused) rays are usually common (Fig. 32); however, they are infrequent or absent in Androstachys (Fig. 31), Choriceras, Parodiodendron, Tetracoccus, and the AustralianPseudanthinae. Aggregate rays were observed in Choriceras only. Rays are usually heterocellular (Figs. 28, 29), which is generally considered the primitive condition. Homocellular procumbent rays are shared by Androstachys and WOOD ANATOMY Growth rings are often absent or only faintly visible. Growth rings are present, however, in Androstachys, Celaenodendron (Fig. 23), Parodiodendron, Petalostigma, Podocalyx, Tetracoccus, and Australian Pseudanthinae (Fig. 24); except for Podocalyx, from the upper Amazon and Orinoco drainage basins, these are plants of dry habitats with strongly seasonal availability of moisture. Pores are evenly distributed (i.e., diffuse porous in species with growth rings), except in the ring porous wood of Tetracoccus, which extends into desert regions of western North America. Pore outlines are mostly circular, generally small, and usually less than 100 Atm diam.; pore diameters are often less than 50 Atmin the genera mentioned above from dry habitats. Perforation plates are overwhelmingly simple, but scalariform plates are found in Paradrypetes (exclusively so according to Mennega (1987), mixed with simple perforations according to Araujo & Mattos Filho (1984)) and mixed simple, scalariform (Fig. 30), and reticulate plates characterize Podocalyx. Intervascular pits are transitional in Paradrypetes and Podocalyx; otherwise they are alternate and mostly small, ca. 5 Aim or less. Very small intervascular pits (2-3 ,um) are found in Aristogeitonia, Neoroepera, and Pseudanthus; somewhat larger than usual pits (6-8 ,um) occur in Austrobuxus, Celaenodendron, Parodiodendron, Picrodendron, Piranhea, and Podocalyx. Vessel element lengths for most genera fall within the range of 400-700 ,um; vessel elements are somewhat shorter in Picrodendron (ca. 300 Aim), somewhat longer in Dissiliaria (ca. 800 gim), Austrobuxus (ca. 950 ,im), and Paradrypetes (ca. 1200 ,im), and longest in Podocalyx (ca. 1250 ,im). Sculpture on the inner surface of vessels is rare; some vessels of Choriceras possess spiral of are characteristic thickenings; thickenings Whyanbeelia (spiral only) and Tetracoccus (spiral Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae 191 AMAMI Wood anatomy of Oldfieldioideae.-22. Austrobuxus swainii (deBeuzeville s.n., MADw 10449), FIGURES22-27. note thin- and thick-walled fibers.-23. Celaenodendron mexicanum (Ortega 35, USw 3886), note long radial multiplesof pores and boundariesof growth ring (top and bottom). -24. Micrantheum hexandrum ( Whaite & Whaite 3536), note bands of gelatinous fibers.-25. Piranhea trifoliata (Ducke s.n., USw 31485), note banded distribution Oldfieldia of axial xylem parenchyma.-26. Androstachys johnsonii (Pretoria UIND 2127, Uw 21991).-27. africana (Cooper 88, USw 4517). All bars = 100 Am. Annals of the Missouri Botanical Garden 192 TABLE 1. Wood structure of biovulate euphorbs, after Metcalfe & Chalk (1950). Feature Aporusa-type "Other genera" Glochidion-type Perforations Fibers scalariform, simple, or both nonseptate, thick-walled simple nonseptate, thick-walled simple septate, thin to moderately thick-walled Parenchyma abundant, diffuse or narrow bands abundant, diffuse to wide bands absent or scanty some species of Oldfieldia, which serves to demonstrate that these woods are not as dramatically distinct as Metcalfe & Chalk (1950) suggested. Homocellular square to erect rays are one of several synapomorphiesthat mark the Australiangenera of Pseudanthinae as a distinct monophyletic group. Vessel to ray pits are of two forms that appear to hold great systematic significance. The most distinctive pattern consists of highly irregular pits that range from circular to elongate with the elongate pits at various orientations: vertical, horizontal, or diagonal (Fig. 28). This irregularpattern is interpreted as primitive by virtue of its resemblance to primitive transitional intervascular pitting, and by its occurrence in Paradrypetes and Podocalyx (see below); irregular vessel-ray pits have been retained by all arborescent Australasian genera. All other genera possess uniform vesselray pits that are circular and alternate. If circular, alternate vessel-ray pits are indeed the derived character state, this feature evolved twice, since the Australian Pseudanthinae (i.e., Caletieae sensu stricto) are clearly derived from the lineage bearing the arborescent genera of Australasia (see below), rather than the lineage of African and American genera. Ray cells generally bear only tannins, but several exceptions occur: prismatic crystals are sporadic in Podocalyx, abundant in Paradrypetes (Araujo & Mattos Filho, 1984); silica deposits are common in Petalostigma; and sclerified cells bearing a prismatic crystal are abundant in Aristogeitonia, Mischodon, and Tetracoccus fasciculatus; these crystalliferous cells are only rarely present in Voatamalo. Perforated ray cells are sporadic in Paradrypetes (Milanez, 1935), Podocalyx, and Hyaenanche, but have not been observed in other Oldfieldioideae.Perforated ray cells are fairly widespread in Euphorbiaceae according to Giraud (1983), who recorded this feature in the following phyllanthoid genera: Aporusa, Baccaurea, Bridelia, Cleistanthus Hook. f. ex Planch., Drypetes, Hyeronima, and Richeria. Perforated ray cells are also present in Putranjiva (Nazma et al., 1981) and Amanoa (unpublished obs.). Axial xylem parenchyma is mostly diffuse and (Fig. 27), with bands also diffuse-in-aggregates present in Aristogeitonia, Dissiliaria, Parodiodendron (strictly initial bands), Picrodendron, Piranhea (Fig. 25), and Voatamalo; on the other hand, parenchyma is infrequent and restricted to a few abaxial scanty paratracheal cells in Androstachys, Stachyandra, and the Australian genera of Pseudanthinae (Fig. 24). Parenchyma strands usually contain both ordinary cells and short sclerified cells bearing a single prismatic crystal (Fig. 21); crystalliferous parenchyma is absent, how- ever, in Paradrypetes, Podocalyx, Petalostigma, Whyanbeelia, the Australian genera of Pseudanthinae, and most specimens of Tetracoccus. Since sclerified crystalliferous axial xylem parenchyma cells are common in several phyllanthoid woods (e.g., Amanoa and Drypetes), presence of such cells may be considered primitive for Oldfieldioideae; their loss may well be synapomorphous for Petalostigma,f Whyanbeelia, and the Australian genera of Pseudanthinae; loss in others (e.g., Paradrypetes, Podocalyx, and most specimens of Tetracoccus) may represent convergent developments. ORIGIN OF OLDFIELDIOIDEAE EVIDENCE FROM WOOD ANATOMY The analysis of wood structure of biovulate euphorbs contained in Metcalfe & Chalk (1950) provides a convenient starting point for discussion of relationships between Phyllanthoideae and Oldfieldioideae. In this work, three groups of genera were distinguished, as indicated in Table 1. At the most superficial of levels, woods of Oldfieldioideae, largely included in Metcalfe & Chalk's "other genera," may be characterized as a combination of the vessel features of Glochidion-type woods and the fiber and parenchyma features of Aporusa-type woods, the latter two categories consisting primarily of phyllanthoid genera. In some instances these three coarsely defined categories provide a useful perspective for placing genera; for example, the re- 193 Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae moval of Neowawraea Rock, which has Glochidion-type wood, from Drypetes, which has Aporusatype wood, and its subsequent submergence into Flueggea Willd., which also has Glochidion-type wood (Hayden & Brandt, 1984; Hayden, 1987). However, as wood structure of biovulate euphorbshas become better known, genera with wood that is transitional between the three categories cloud what once appeared to be a clear picture. For example, Mennega (1984) found tribal placement of Jablonskia Webster difficult, essentially because the wood of Jablonskia has an unusual combination of characters: specifically, vessel features of Aporusa-type woods and fiber and parenchyma features of Glochidion-type woods. In short, Jablonskia represents the reverse of the combination that characterizes most oldfieldioids. Mennega (1987) has noted additional transitional genera in her extensive survey of wood structure in Phyllanthoideae; moreover, woods of some phyllanthoids, e.g., Lachnostylis Turcz. and Savia, match the typical oldfieldioid pattern described above. Further, within Oldfieldioideae,Podocalyx and Paradrypetes possess essentially typical expressions of Aporusa-type structure. Clearly, the simple rubric of three wood types for biovulate euphorbs requires modification. An evolutionary perspective of anatomical characters helps to clarify some of the complexity seen in woods of biovulate euphorbs. In accord with widely accepted hypotheses of wood evolution, Mennega (1987) has identified woods with long vessel elements, long scalariformperforationplates, mediumto large intervascularpits, long thick-walled nonseptate fibers with bordered pits on both radial and tangential walls, and diffuse or narrowly banded axial xylem parenchyma to be primitive within Phyllanthoideae. Extant genera such as Aporusa, Blotia, and Protomegabaria Hutch. retain these features. Carlquist(1975) has argued convincingly that primitive vessel features are adaptive only in uniformly moist forest environments that impose minimal demands for water conduction. It may be assumed that adaptive radiation of primitive biovulate euphorbs into drier, or seasonally drier, habitats would be accompanied by evolution of more advanced vessel features. Similarly, one may reasonably suppose exploitation of nonforest and/or seasonal habitats to be associated with modification of mechanicaland storage requirementsof the wood; such changes would be manifest in both fiber and parenchyma features. Much of the diversity of biovulate euphorb wood structure may thus be interpreted in terms of divergence from primitive Aporusa-type structure, an ecologically restrictive syndrome of xylem features. Within Phyllanthoideae, Aporusa- and Glochidion-type structure represent evolutionary extremes, but numerous transitional forms can be identified from Mennega's (1987) data. For example, tracking both perforation plates and development of septate fibers yields the following series of forms that may be viewed as intermediates between Aporusa- and Glochidion-type structure: Actephila, Chascotheca Urb., and Pentabrachium Muell. Arg. with exclusively scalariform perforations and some septate fibers; Celianella Jabl., Didymocystis Kuhlm., and Jablonskia with mixed simple and scalariform perforations and some septate fibers; Astrocasia Rob. & Greenm. and Discocarpus Klotzsch with simple perforations, but only some septate fibers. Similarly, within Aporusa-type woods, there is a clear transition of perforation plates from exclusively scalariformin Aporusa, Heywoodia, Hyeronima, Maesobotrya Benth., and Putranjiva, to mixed simple and scalariform in numerous genera and, finally, to exclusively simple in Lachnostylis and Savia. Of course, such sequences of extant genera should not be interpreted as the actual course of xylem evolution within Phyllanthoideae. In terms of the gross vessel, fiber, and parenchyma features of Table 1, the evolutionary transformation of wood in Oldfieldioideaeseems parallel to that noted for Aporusa-type woods. In comparison, Phyllanthoideae experienced a greater range of wood diversification with the additional development of Glochidion-type woods. Within Oldfieldioideae, Podocalyx and Paradrypetes stand out as probably the most primitive woods by virtue of their very long vessel elements, multiple perforation plates, and large transitional intervascular pits; presence of perforated ray cells in these genera may also be interpreted as primitive features. Overall, their woods are comparable to primitive phyllanthoid woods with Aporusa-type structure. The primitive woods of Paradrypetes and Podocalyx excepted, Oldfieldioideaegenerally have exclusively simple perforationplates and have lost perforated ray cells, but otherwise retain the features of Aporusa-type structure (cf. comments on Lachnostylis and Savia, above). Much of the diversity of oldfieldioidwoods is restricted largely to what are, perhaps, minor themes such as element size (Figs. 22-27), vessel grouping (Figs. 22-27), ray dimensions (Figs. 31-33), vessel-ray pitting, and parenchyma distribution(Figs. 22-27). These minor themes, however, are responsible for con- 194 Annalsof the MissouriBotanicalGarden p FIGURES28-33. ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~ S~~~~~~~~~~~~~ ad Wood anatomyof Oldfieldioideae.-28.Austrobuxusswain~ii(Symingtons.n., Uw 2141 1), radial section, heterocellular ray and irregular slitlike vessel-ray pits. -29. Petalostigma sp. (SFCw R594-2), radial section, heterocellular rays and simple perforation plates.-30. Podocalyx loranthoides (Wurdack & Adderley 42 795, MADw 2242 9), radial section, scalariform perforation plate. - 31. Androstachys johnsonii (Pretoria UIND 2127, Uw 21991), tangential section, short and narrow rays.-32. Celaenodendron mexicanum (Ortega 35, USw 3886), tangential section. -33. Tetracoccus fasciculatus var. fasciculatus (Johnston 7783), tangential section, wide rays. All bars = 100 ,um. Volume 81, Number 2 1994 siderable diversity of oldfieldioid woods; based on wood features alone, it is entirely understandable that Metcalfe & Chalk (1950) sought to associate oldfieldioidgenera with woods from other subfamilies. The presence of somewhat primitivewoods (Paradrypetes and Podocalyx) in Oldfieldioideaesuggests that the divergence of Oldfieldioideae from Phyllanthoideae occurred quite early in the evolution of Euphorbiaceae, from ancestral stocks with relatively primitiveAporusa-type woods. The symplesiomorphousnature of wood features at the evolutionary transition between the subfamilies precludes the possibility of specifying one or another phyllanthoid group as closest to the origin of Oldfieldioideae based on this tissue alone. Septate fibers, common in phyllanthoids with Glochidion-type structure, occur in only one oldfieldioid, Parodiodendron. One prominent difference, however, between this wood and the Glochidion-type phyllanthoids is its fairly abundant parenchyma present in initial bands, diffuse apotracheal and scanty paratracheal configurations. Typical expressions of Glochidion-type structure include very little parenchyma at all. The occurrence of septate fibers in Parodiodendron may thus represent convergence. EVIDENCE FROM STOMATALSTRUCTURE Configuration of the stomatal apparatus is one of the most consistent features of leaves of Oldfieldioideae. Most genera possess brachyparacytic patterns in which the subsidiary cells substantially overlie the adjacent guard cells. In this regard, Levin (1986), upon whose data much of the following is based, has shown stomatal patterns of the phyllanthoidtribes to be fairly diverse; in fact, this character provides important evidence in identifying which phyllanthoids are closest to the origin of Oldfieldioideae.As argued above, it will be necessary only to consider tribes with Aporusa-type wood structure. Aporuseae may be eliminated from further consideration by its consistently anisocytic stomata, a pattern never found in Oldfieldioideae. Paracytic or brachyparacytic stomata are found in the remaining tribes under consideration, i.e., Amanoeae, Antidesmeae, Drypeteae, and Wielandieae, with brachyparacytic in only Drypeteae and some Wielandieae. Subsidiary cells in Drypetes, like those of most Oldfieldioideae,partially overlie the adjacent guard cells. The brachyparacytic subsidiary cells of Lachnostylis (tribe Wielandieae) are frequently subdivided (Levin, 1986), another common character in Oldfieldioideae. Unfortunately, the distribution of stomatal characters in Hayden Euphorbiaceae Subfamily Oldfieldioideae 195 Phyllanthoideae and Oldfieldioideaeprecludes any simple statement about the point of divergence of the two subfamilies. Both characater states of three important characters (paracytic-brachyparacytic, entire-subdivided subsidiary cells, and coplanar"piggyback" subsidiary cells) are found in both groups. This situationmay be viewed as an example of Cronquist's (1988) assertion that parallel tendencies are reasonably good indicators of relationships; a rigorous cladistic analysis of Phyllanthoideae and Oldfieldioideae should distinguish the synapomorphic stomatal characters from the parallelisms. ADDITIONALEVIDENCE A number of anatomical characters such as the occurrence of theoid teeth, intersecondary veins, and mucilaginous epidermis in Oldfieldioideaeand primitive Phyllanthoideae are consistent with the former's derivation from the latter. Floral structure of Wielandieae is sufficiently generalized to be consistent with ancestral status. However, plesiomorphous characters such as these do not present by themselves an overly compelling case for consanguinity. On the other hand, the often reduced carpel number and drupaceous fruits of Drypetes show greater (or, at least, different) specialization than that found in many Oldfieldioideae.Further, chromosome numbers of n = 20 for Putranjiva (Gill et al., 1981) and 2n = 40 for Drypetes (Webster, 1967) are difficult to resolve with the counts suggesting x = 12 for Oldfieldioideae (see above). Extant Drypeteae are thus unsuitable as progenitors for Oldfieldioideae,but it remains conceivable that these taxa may have shared a common ancestor. Levin & Simpson (1988) noted that the spinules and discontinuous exine foot layer in pollen of Securinega Comm. ex Juss. sensu stricto suggested a close relationship with Oldfieldioideae. Despite exclusively simple perforation plates, the wood of Securinega conforms well to the Aporusa-type (and thus may be out of place in tribe Phyllantheae, as pointed out by Mennega (1987)). Securinega also possesses paracytic stomata (Gaucher, 1902). Further anatomical data would be most useful. In our present state of ignorance, Securinega stands as another possible near relative to Oldfieldioideae. SUMMARY Taken together, stomatal and wood characters suggest that Oldfieldioideaediverged from the early differentiationof the primitive biovulate tribe Wielandieae perhaps along some of the same lines that 196 Annals of the Missouri Botanical Garden Tribe Picrodendreae (Small) Webster.The genultimately led to the modern genera Drypetes and/ or Securinega. In a larger context, presence of era with palmately compound leaves form the contheoid teeth and palmately compound leaves in ceptual nucleus of tribe Picrodendreae. Bentham Oldfieldioideaelends supportto Dilleniidrather than (1878) was the first to group together the biovulate Rosid derivation of Euphorbiaceae (cf. discussion euphorbs with compound leaves, associating Oldin Levin (1986)). fieldia and Piranhea with the non-oldfieldioidgenus Bischofia. Later, Aristogeitonia (Prain, 1912; Pax & Hoffmann, 1922, 1931) and CelaenodenRELATIONSHIPS WITHIN OLDFIELDIOIDEAE dron (Hutchinson, 1969) were added to this group, Classification of subfamily Oldfieldioideae has which (minus Bischofia) constituted subtribe Paibeen in a state of flux over the past three decades. vaeusinae of Webster (1975). (Presence of nonThe followingdiscussion focuses on anatomical data spiny pollen (K6hler, 1965) and Glochidion-type as indicators of relationshipswithin Oldfieldioideae, wood structure (Mennega, 1987) shows Bischofia specifically, the role of anatomy in modification of to be better placed in Phyllanthoideae.) Webster (1975) maintained Picrodendron in a monogeneric early classifications of Oldfieldioideae (Khler, 1965; Webster, 1975) and the extent that anat- tribe, but anatomical evidence (Hayden, 1977, 1980, see also below) suggests a close relationship omy supports the most recent classifications of these plants (Levin & Simpson, 1994; Webster, among the oldfieldioidgenera with compoundleaves. 1994). Presently, Picrodendreae includes all oldfieldioids Tribe Croizatieae Webster. Croizatia, the only with compound leaves (e.g., Stachyandra), plus several others with unifoliolate (Parodiodendron genus of the tribe, is anatomically unknown. Tribe Podocalyceae Webster. The genera as- and species of Aristogeitonia) or evidently simple sociated with Podocalyx have undergone radical leaves (Androstachys, Mischodon, and Voatarevision in the brief history of Oldfieldioideae.K6h- malo) (Levin & Simpson, 1994; Webster, 1994). ler (1965) grouped Podocalyx with several genera Picrodendreae is characterized anatomically by alof tribe Picrodendreae that have compound leaves ternate vessel-ray pits, bundle sheath extensions plus Tetracoccus, whereas Webster (1975) asso- bearing crystals, well-developed areoles, and fimciated it with some of the simple-leaved genera of brial veins at leaf margins. Anatomical data support a subdivision of PicroPicrodendreae plus, again, Tetracoccus. As discussed below, the genera of Picrodendreae, wheth- dendreae that has been adopted by Levin & Simpson (1994) and Webster (1994). The first group er bearing simple or compound leaves, form a reasonably well-defined lade and are thus better is African-Madagascan-Sri Lankan and consists classified elsewhere. Of the two classifications pre- of And rostachys, Aristogeitonia, Mischodon, sented in this volume, both link Podocalyx with Stachyandra, and Voatamalo; these genera may Paradrypetes, albeit each in separate subtribes, be defined by stipules adnate to the petiole (Airy but only Webster continues to include Tetracoccus Shaw, 1970, 1972; Bosser, 1976; Radcliffe-Smith, in this tribe. There are no compelling anatomical 1988, 1990) and a strong tendency toward unifoliolate or simple leaves. Further, Aristogeitonia, synapomorphies that might serve to unite these three genera. The primitive wood features of ParMischodon, and Voatamalo possess sclerified ray cells bearing prismatic crystals. adrypetes and Podocalyx (see above) suggest that Mischodon was included among the genera of at least these two genera are basal offshoots from the ancestral stem of Oldfieldioideae;as such, they Dissiliariinae by Pax & Hoffman (1931) (see also may not be expected to share many synapomor- Fig. 1) and K6hler (1965). I am in complete agreephies with each other. Each genus of Podocalyceae ment with Raju (1984), who pointed out several bears at least one strikingly unique autapomorphy: differences in stomata and trichomes between the raphides of Paradrypetes, the tracheoid idio- Mischodon and genera of Dissiliariinae. Mischoblasts of Podocalyx, and the ring porous wood of don thus bears no compelling anatomical resemblance to any genus of tribe Caletieae sensu lato. Tetracoccus. The xeromorphic adaptations of Tetracoccus Placement in Picrodendreae is definitely superior might just as easily obscure an early or late di- to any previous classification of the genus, a convergence from ancestral oldfieldioidstocks. Tetra- clusionconfirming,to some extent, suggestionsmade coccus does share alternate vessel-ray pitting with by Airy Shaw (1972) based on the similarity of Picrodendreae, and this character could be used stipules of Aristogeitonia and Mischodon. The second subgroup of Picrodendreae is neoto argue for its inclusion in that tribe, as classified tropical and consists of Celaenodendron, Picroby Levin & Simpson (1994, this volume). 197 Volume 81, Number 2 1994 Hayden Euphorbiaceae Subfamily Oldfieldioideae dendron, and Piranhea; these genera are uniformly trifoliolate, have alternate phyllotaxy, and lack the epidermalmucilage which is so widespread in the family. Parodiodendron, also neotropical, presents an interesting situation. It shares with the trifoliolate genera alternate phyllotaxy and unusually large (for Oldfieldioideae) intervascular pits; but its leaves are unifoliolate and lack the fimbrial vein characteristic of all other members of the tribe. Further, Parodiodendron is unique within the subfamily by virtue of its septate wood fibers. Nevertheless, Parodiodendron seems best accommodated among the other neotropical Picrodendreae, especially if its discordant features are viewed as autapomorphies. Oldfieldia is not included in either of the above groups. Anatomically, its trichomes and presence (in some species) of homocellular procumbent rays resemble these features in the otherwise rather different genera Androstachys and Stachyandra. Oldfieldia may represent a relictual element derived early from the ancestors to Picrodendreae prior to its differentiation into otherwise distinct New and Old World lineages. Levin & Simpson (1994) include Tetracoccus in Picrodendreae, but aside from the alternate vessel-ray pits of these desert shrubs there is no compelling anatomical support for this placement. Tribe Caletieae Muell. Arg. With virtually no contrary opinion on record, Micrantheum, Pseudanthus, and Stachystemon have been recognized as close relatives for well over a century (Agardh, 1858; Mueller, 1866; Bentham, 1880; Grining, 1913; Pax & Hoffmann, 1931; Hutchinson, 1969). These shrubby xerophytes of Australia constitute the traditional circumscription of Tribe Caletieae. Their gross similarity and narrow "Stenolobeae"type cotyledons precluded serious comparison with other euphorbs prior to the utilization of pollen characters in the systematics of Euphorbiaceae. Neoroepera was added to what was then a wholly Australian tribe by Webster (1975) who was impressed, no doubt, by the numerous scattered apertures (Punt, 1962; Kohler, 1965) shared by all four genera. Additional palynological and anatomical studies have refined concepts of relationships to the extent that, now, all Australasian genera except Mischodon are perceived to constitute a single clade, the greatly expanded Tribe Caletieae sensu lato (Levin & Simpson, 1994; Webster, 1994). The presence of crenulate "piggyback" subsidiary cells is a particularly striking synapomorphy linking all Australasian genera of Oldfieldioideae, plus the monotypic Hyaenanche, endemic to the western Cape of South Africa. Hyaenanche has no other obvious close relatives within Oldfieldioideae. Anatomically, its marginal venation is remarkable, but, apparently, autapomorphic. It is perhaps best viewed as a remnant of the Australasian stem of the subfamily, from which it has been separated since the breakup of Gondwanaland. Placement of Hyaenanche in a separate monogeneric subtribe seems appropriate. Hyaenanche excluded, all other members of Tribe Caletieae share another epidermal feature, longitudinally chambered cells that bear copious mucilage deposits in their lower halves. Taken together, crenulate subsidiary cells and mucilaginous epidermis provide a robust definition of the Australasian lade. The Australasian genera also tend to have relatively low rank foliar venation and poorly defined areoles, but it seems these vein features are best interpreted as plesiomorphic. The distinctive epidermal features of Caletieae sensu lato are found in Scagea, which argues strongly for its placement here and not in Acalyphoideae or Crotonoideaeas suggested by McPherson (1985); the uniovulate carpels of Scagea may thus be homoplasious with Acalyphoideae, Crotonoideae, and Euphorbioideae. Both Webster (1994) and Levin & Simpson (1994) dividethe Australasianoldfieldioidsinto three subtribes, Dissiliariinae, Petalostigmatinae, and Pseudanthinae. Aside from the epidermal characters that define the entire Australasian lade of Oldfieldioideae,the genera of subtribe Dissiliariinae share few phylogenetically significantanatomicalstructures. Woods of Dissiliariinaehave irregular vessel-ray pits (Fig. 28), but this is probably a plesiomorphic feature in the subfamily. Leaf margins tend to be entire in Oldfieldioideae,but, as noted above, exceptional toothed leaves occur in species of Austrobuxus, Choriceras, and Dissiliaria, and this feature, too, is probably plesiomorphic. Austrobuxus, with a preponderance of solitary pores, long vessel elements (often > 1 mm), occasional scalariform perforations, and abundant tracheids, seems to be the least specialized genus of the subtribe in terms of wood anatomy. Anatomically, Dissiliaria stands apart from the remainder of its tribe by virtue of high rank venation, well-developed and somewhat oriented areoles, narrow ultimate tracheids in veinlets, fimbrial veins, wavy anticlinal walls of leaf epidermis cells, bundle sheath extensions, and libriform wood fibers. W'hyanbeelia lacks crystal-bearing axial xylem parenchyma; in this respect it resembles wood of Petalostigma and Pseudanthinae; its retention in 198 Annals of the Missouri Botanical Garden Dissiliariinaemay be challenged on this character. Lack of wood material precludes determining whether Scagea and Kairothamnus are better included in Dissiliariinae(crystalliferous axial xylem parenchyma present) or either Petalostigmatinae or Pseudanthinae (said crystals absent); pollen suggests relationship with Pseudanthinae (Levin & Simpson, 1994). Subtribe Dissiliariinaeappears to be a paraphyletic assemblage at the base of the Australasian lade. Petalostigma is a distinctive genus of Australia and southern New Guinea characterized, as its name suggests, by broad petaloid stigmas. The presence of crenulate subsidiary cells and chambered epidermal cells with mucilage shows the association of Petalostigma with Australasiangenera of Oldfieldioideaeto be superior to its former association with Androstachys (Webster, 1975; Hayden, 1982); this realignment is also supported biogeographically. Both Levin & Simpson (1994) and Webster (1994) place Petalostigma in its own monogeneric tribe, evidently because its pollen bears at least some apertures out of the equatorial plane (Punt, 1962; K8hler, 1965), thus differingfrom the pollen of Pseudanthinae. Nevertheless, Petalostigma shares some anatomical features with Pseudanthinae: lack of crystalliferous axial xylem parenchyma and the presence of nonlignified phloem fibers in foliar veins. In Petalostigma the phloem fibers are thin-walled, whereas in Pseudanthinae the walls are so thick that lumina are almost completely occluded, so the similarity is only partial in this regard. From the numerous comments above in the anatomical descriptions, it is clear that the four Australian genera of subtribe Pseudanthinae (i.e., tribe Caletieae in the traditional or narrow sense) are united by a suite of characters involving leaf architecture, leaf anatomy, and wood structure (see also Hayden, 1981). Many of the anatomical characters of these genera suggest a sequence of increasing xeromorphyinvolving general reduction of leaf size, increasing disorganizationof the venation, and increasing prominence of a massive sclerenchymatous marginal vein. Neoroepera is particularly interesting in that N. buxifolia Muell. Arg. is similar to Dissiliariinaein some characters (incomplete marginal ultimate venation and lignified phloem fibers in foliar veins), whereas N. banksii Benth. conforms with other Pseudantheae (massive intramarginal vein and unlignified phloem fibers). Radcliffe-Smith's (1993) inclusion of Stachystemon within Pseudanthus increases the diversity of venation patterns in the latter, but otherwise these taxa are quite similar anatomically and evidently very closely related. Levin & Simpson (1994) provide further discussion of the relationshipsof Kairothamnus, Neoroepera, Petalostigma, and Scagea with the other genera of Pseudanthinae. LITERATURE CITED J. G. 1858. Theoria Systematis Plantarum ... C. W. K. Gleerup, Lund. AIRY SHAW, H. K. 1965. Diagnoses of new families, new names, etc., for the seventh edition of Willis's "Dictionary." Kew Bull. 18: 249-273. * 1966. A Dictionary of the Flowering Plants and Ferns, Ed. 7. Univ. Press, Cambridge. * 1970. 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IAWA Bull. n.s. 9: 203-252. STONE, H. 1904. The Timbers of Commerce and Their Identification. William Rider & Son, London. WEBSTER, 1967. The genera of Euphorbiaceae in the southeastern United States. J. Arnold Arbor. 48: 303-430. 1975. Conspectus of a new classification of the Euphorbiaceae. Taxon 24: 593-601. 1987. The saga of the spurges: A review of classification and relationships in the Euphorbiales. Bot. J. Linn. Soc. 94: 3-46. 1994. Synopsis of the genera and suprageneric taxa of Euphorbiaceae.Ann. MissouriBot. Gard. 81: 33-144. & K. I. MILLER. 1963. The genus Reverchonia (Euphorbiaceae). Rhodora 65: 193-207. , L. GILLESPIE & J. STEYERMARK. 1987. Systematics of Croizatia (Euphorbiaceae).Syst. Bot. 12: 1-8. WORBES, M. 1989. Growth rings, increment and age of trees in inundation forests, savannas and a mountain forest in the Neotropics. IAWA Bull. n.s. 10: 109-122. SOLEREDER, APPENDIX 1. Specimens of Oldfieldioideaeexamined. Xylarium acronyms follow Stern (1988). Androstachys johnsonii Prain. Leaf: Gomes & Sousa 2202 (K); Wellcome Chemical Research Laboratory s.n. (K). Wood: Capuron 3594.R.4, USw 27434 (= CTFw 13817) (TAN); DDw 2385; Pardy s.n., USw 21255 (= Uw 14606); Pretoria UIND 2127, Uw 21991; PRFw 20686. Aristogeitonia monophylla Airy Shaw. Leaf: Bally & Smith B 14376 (K). Woody twig: Tanner 3386 (K). Aristogeitonia sp. Begue 727.R.1, CTFw 13770 (TAN). Austrobuxus brevipes Airy Shaw. Leaf: Stauffer & Blanchon 5751 (K). Wood: McPherson 4579 (MO). Austrobuxus carunculatus (Baill.) Airy Shaw. Leaf: Baumann-Bodenheim 16087 (US). Austrobuxus clusiaceus (Baill.) Airy Shaw. Leaf: McKee 2570 (US); Webster 14972 (DAV). Woody twig: Webster 14972 (DAV). Austrobuxus cuneatus (Airy Shaw) Airy Shaw. Leaf: McKee 12184 (K). Austrobuxus eugeniifolius (Guillaum.)Airy Shaw. Leaf: Guillaumin & Baumann-Bodenheim 12908 (US); Hurlimann 1331 (US). Austrobuxus horneanus (A. C. Smith) Airy Shaw. Leaf: A. C. Smith 6669 (US). Wood: A. C. Smith 6872, Aw 28453 (= USw 30522), (A, US). Austrobuxus huerlimannii Airy Shaw. Leaf: McKee 4850 (K). Austrobuxus lugubris Airy Shaw. Leaf: McKee 25773 (K). Austrobuxus montanus (Ridl.) Airy Shaw. Leaf: Wray & Robinson 5424 (K). Austrobuxus nitidus Miq. Leaf: Chew & Corner RSNB 4107 (US); Chew & Corner RSNB 4608 (US). Wood: FPAw DFP 30239; PRFw 21393 (SAR);PRFw 21395 (SAR); Si Boecca 7983, USw 29100 (MICH); Sy- Volume 81, Number 2 1994 mington s.n., Uw 21411 (= KEPw 3602) (KEP); USw 30796, Uw 14635, (= SARFw 13234) (SAR). Austrobuxus ovalis Airy Shaw. Leaf: McKee 26894 (K). Austrobuxus paucifiorus Airy Shaw. Leaf: BaumannBodenheim 14113 (K); McPherson 3935 (MO).Wood: McPherson 3923 (MO);McPherson 3935 (MO);McPherson 4603 (MO). Austrobuxus rubiginosus (Guillaum.) Airy Shaw. Leaf: Baumann-Bodenheim 15010 (US); Hurlimann 1486 (US). Austrobuxus swainii (de Beuzev. & C. T. White) Airy Shaw. Leaf: Boorman s. n. (NSW); Hewitt s. n. (NSW); Johnson & Constable s.n. (NSW). Wood: de Beuzeville s.n., MADw 10449 (= FPAw DFP 8606). Austrobuxus vieillardii (Guillaum.) Airy Shaw. Leaf: Schmid 2514 (K). Wood: McKee 25222, FPAw DFP 33881 (K). Austrobuxus sp. Leaf: University of California, Davis Greenhouse B73.173. Wood: Hyland 6918 (DAV); Webster & Hyland 18927 (DAV). Celaenodendronmexicanum Standley. Leaf: Ortega 4962 (US); Ortega 6367 (US). Wood: Ortega 35, USw 3886 (= Aw 4494, MADw 29901, MAD-SJRw 1200); Ortega 6367 (US); Uw 21735 (= Aw 30657). Choriceras tricorne (Benth.) Airy Shaw. Leaf: Forman s.n. (LAE, US). Wood: Pullen 7135, MADw 29097, FPAw-Pullen 7135 (A, CANB, K, L, LAE). Dissiliaria baloghioides F. v. Muell. Leaf: Bailey s.n. (US); Francis & White s.n. (US). Wood: Bailey's Queensland Woods 366, Aw 26736; PRFw 28015; USw 32037, Uw 14625 (= FPAw DFP 3127). Hyaenanche globosa (Gaertn.) Lam. Leaf: Bayliss BSBRI 576 (US); Godfrey SH-1257 (US); Werderman & Oberdieck 528 (US). Wood: Bohmer & Verdoucq s.n. (PRE); Botanical Research Institute Pretoria s.n. (PRE); Werderman & Oberdieck 528 (US). Kairothamnus phyllanthoides (Airy Shaw) Airy Shaw. Leaf: Johns NGF 47324 (K); Streimann NGF 45108 (K). Longetia buxoides (Baill.) Airy Shaw. Leaf: BaumannBodenheim 5605 (US). Wood: Baumann-Bodenheim 5605 (US). Micrantheum demissum F. v. Muell. Leaf: Hunt 2802 (US). Woody twig: Hunt 2802 (US). Micrantheum ericoides Desf. Leaf: Hotchkiss 428 (US); Johnson & Constable 19095 (US). Woody twig: Cambage 495 (NSW). Micrantheum hexandrum Hook. f. Leaf: Boorman s.n. (US); McGillivray 3196 (DAV); Schodde 1177 (US). Woody twig: Boorman s.n. (US); Whaite & Whaite 3536 (NSW). Mischodon zeylanicus Thwaites. Leaf: Ripley 05 (US); Wheeler 12079 (US). Wood: Jayasuriya 2434 (PDA); Wheeler 12079 (US). Neoroepera banksii Benth. Leaf: Banks & Solander s. n. (US). Woody twig: Horner & Taylor s.n. (NSW). Neoroepera buxifolia White. Leaf: White 12095 (US). Woody twig: White 12095 (US). Oldfieldia africana Benth. & Hook. f. Leaf: Cooper 88 (K, MAD, US); Cooper 439 (US). Wood: Commercial sample, USw 19900; Cooper 88, USw 4517, Uw 14636 (= Aw 16930, MADw 30131, MAD-SJRw 13738) (K, MAD, US); Cooper 111, USw 4538, (= Aw 16931, MADw 30132, MAD-SJRw 13761) (K, MAD); Cooper 295, USw 4882, (= Aw 16932, MADSJRw 15207) (MAD). Oldfieldia dactylophylla (Weiw. ex Oliv.)L6onard.Wood: Hayden Euphorbiaceae Subfamily Oldfieldioideae 201 Cons. For. Tanganyika Territory 254, Uw 10951 (PRFw 13495). Oldfieldia macrocarpa L6onard. Wood: Dechamps (Comite Nat. du Kivu) s.n., TERVw 1605 (BR). Oldfieldia somalensis (Chiov.) Milne-Redhead.Leaf: Perdue & Kibuwa 10005 (NA). Wood: Schlieben 6371 (wood no. 558), Uw 15635 (= MAD-SJRw 34030). Oldfieldia sp. Wood: Dechamps 330, TERVw 7522; Dechamps 335, TERVw 7527; Dechamps 655, TERVw 8499 (BR). Parodiodendron marginivillosum (Speg.) Hunziker.Leaf: Hueck 469 (US). Wood: Vervoorst & Cuezzo 7.610C (LIL). Petalostigma banksii Britten & S. Moore. Leaf: Perry 1981 (US); Perry 3531 (US); Perry 3562 (US). Wood: Doherty s.n., USw 21280. Petalostigma "glabrescens" (probably referable to P. pubescens or P. triloculare). Leaf: Clemens 42580 (US); Wilson 679 (US). Wood: SFCw R 594-2. Petalostigma pubescens Domin. Leaf: White 12421 (US). Wood: SFCw R 594-3; SFCw R 977-256; White s.n., PRFw 17591. Petalostigma quadriloculare F. v. Muell. Leaf: Clemens 42561 (US); Lazarides 6669 (US). Wood: PRFw 2921; PRFw 24259, (= Uw 10949); PRFw 10913, (= Uw 10948); Webster & Hyland 18879 (DAV). Piranhea longepedunculata Jablonski. Leaf: Breteler 4969 (US). Wood: Breteler 4970, MAD-SJRw55650, (= Uw 12254) (MER, US); Breteler 5096, USw 35682, ( Uw 12306, MAD-SJRw 55702) (MER, NY, U, US, WAG). Piranhea trifoliata Baill. Leaf: Krukoff5924 (US); Steyermark 86615 (US). Wood: Capucho 493, USw 22377 ( Aw 4526, MADw 30166, MAD-SJRw 23457) (F, IAN); Ducke s.n., USw 31485 (MAD); Krukoff 6163, USw 7524 (US). Podocalyx loranthoides Klotzsch. Leaf: Bernardi 1675 (NY); Froes 21543 (NY); Krukoff 811 (NY); Williams 14480 (US). Wood: Wurdack & Adderley 42795, MADw 22429 (= MAD-SJRw 54246) (NY, US). Pseudanthus divaricatissimus (Muell. Arg.) Benth. Leaf: Constable 53354 (US); Ingram s.n. (NSW). Woody twig: Constable 53354 (US); Ingram s.n. (NSW). Pseudanthus orientalis F. v. Muell. Leaf: Clemens 44092 (US); Wilson 639 (US). Woody twig: Clemens 44092 (US). Pseudanthus ovalifolius F. v. Muell. Leaf: Beauglehole & Orchards 30452 (NSW); Muir 906 (US). Woody twig: Beauglehole & Orchards 30452 (NSW); Muir 906 (US). Pseudanthus pimelioides Sieb. ex Spreng. Leaf: Boorman s.n. (US); Clemens 42750 (US). Woody twig: Boorman s.n. (US); Clemens 42750 (US); Constable NSW 55972 (NSW). Scagea depauperata (Baill.) McPherson. Leaf: Franc 1642a (US). Scagea oligostemon (Guillaum.)Airy Shaw. Leaf: Guillaumin & Baumann-Bodenheim 11808 (US); McKee 2352 (US); McKee 2651 (US). Stachyandra merana (Airy Shaw) A. Radcliffe-Smith. Leaf: Baron 6431 (K); Capuron 23335-5F (K). Stachyandra viticifolia (Airy Shaw) A. Radcliffe-Smith. Leaf: Capuron 20975 SF (K). Wood: Capuron 1914.R.4, CTFw 9069 (TAN). Stachyandra sp. Wood: Belin 218.R.6, CTFw 13786 (TAN). 202 Annals of the Missouri Botanical Garden ou (1940); Heimsch (1942); MC; Bamber (1974); Rao & Raju (1985). CelaenodendronStandley. Record(1928); Record (1938); Record & Hess (1943); Hayden (1977). Croizatia Steyerm. Levin (1986). Dissiliaria F. Mueller.MC;Dehay (1935); Bamber(1974); Rao & Raju (1985). Hyaenanche Lambert & Vahl. Pax (1884); G; S; Dehay (1935); Assailly (1954). Longetia Baillon. Much publishedanatomical information on "Longetia" pertains to Austrobuxus nitidus (= Longetia malayana); there appears to be no previous anatomical study of Longetia buxoides (Baill.) Airy Shaw. Micrantheum Desfontaines. Pax (1884); G; S; MC; Rao & Raju (1985). Mischodon Thwaites. G; Gamble(1922); Heimsch (1942); MC; Raju (1984); Rao & Raju (1985). Neoroepera Mueller Arg. Rothdauscher (1896). Oldfieldia Bentham. Stone (1904); MC; Assailly (1954); Lebacq & Dechamps (1964); Bolza & Keating (1972); Hayden (1977); Rao & Raju (1985). Paradrypetes Kuhlm. Milanez (1935); Araujo & Mattos Filho (1984); Levin (1986); Mennega (1987). Petalostigma F. Mueller. Froembling (1896); Rothdauscher (1896); G; S; Dehay (1935); MC; Bamber (1974); Rao & Raju (1985). APPENDIX 2. Previous anatomical literature on Oldfieldioi- Picrodendron Planchon. Hayden (1977) (q.v. for earlier deae. Comprehensive works abbreviated as follows: G = references); Hakki (1985); Rao & Raju (1985). Gaucher (1902); S = Solereder (1908); MC = Metcalfe Piranhea Baillon. Dehay (1935); Record (1938); MC; & Chalk (1950). Hayden (1977); Pyykk6 (1979); Roth (1981); Worbes (1989). Androstachys Prain. Anonymous (1909); MC; Bolza & Pseudanthus Sieber ex Sprengel. Pax (1884); G; S; Rao Keating (1972); Rao & Raju (1985); Alvin (1987); & Raju (1985). Alvin & Rao (1987); Dahlgren & van Wyk (1988). Stachystemon Planchon. Pax (1884); G; MC. Austrobuxus Miquel (often reported as "Longetia," see below). Rothdauscher(1896); G; Dehay (1935); Math- Tetracoccus Engelman ex Parry. Heimsch (1942); MC. Stachystemon axillaris George. Leaf: Blackwell & Grif fin 3132 (PERTH). Stachystemon brachyphyllus Muell. Arg. Leaf: George 12928 (PERTH). Stachystemon polyandrus (F. Muell.) Benth. Leaf: Hnatiuk 761262 (PERTH). Stachystemon vermiculare Planch. Leaf:Pritzel s. n. (US); Royce 5207 (PERTH). Tetracoccus dioicus Parry. Leaf: Moran 13170 (US); Terrell & Gordon 4004 (US); Webster & Hildreth 7478 (DAV). Wood: Campbell 21484 (RSA). Tetracoccus fasciculatus (Wats.) Croizat var. fasciculatus. Leaf: Johnston 7783 (GH, US); Webster,21221 (DAV). Wood: Johnston 7783, Aw 23748 (GH, US). Tetracoccus fasciculatus (Wats.) Croizat var. hallii (Brandegee) Dressler. Leaf: Webster & Hildreth 7460 (DAV); Wiggins 6617 (US). Wood: Webster & Hildreth 7460 (DAV). Tetracoccus ilicifolius Coville & Gilman. Leaf: Gilman s.n. (US); Gilman 2181 (US). Wood: Gilman 2181 (US). Voatamalo eugenioides Capuron ex Bosser. Wood: SF 198 R 259, (= CTFT 13816, Uw 23104); SF 5327 R 4 (= CTFT 15079, Uw 23105). Whyanbeelia terrae-reginae Airy Shaw & Hyland. Leaf: Irvine 1399 (K). Wood: Hyland 7945 (K).

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