627. PHILIBERTIA BARBATA Apocynaceae: Asclepiadoideae D. J. Goyder Summary. Philibertia barbata is illustrated, its habitat is described and its taxonomic relationships outlined. Philibertia, a genus of 43 species, has its centre of diversity in the Andean dry valleys of northern Argentina and southern Bolivia (Goyder, 2004, 2008, in press). It includes rampant twiners with lemon or white, funnel-shaped flowers to 3 cm long such as P. speciosa (Malme) Goyder, and the rock-hugging ‘alpine’ P. lysimachioides (Wedd.) T. Mey. which can occur at altitudes over 4000 m. Leaves are often felted, and most have a lobed base. Flowers generally have a tubular or broadly campanulate corolla, which is often slightly fleshy. But other floral organs are highly variable. Many species lack a corona – which caused problems in their classification until recently, as asclepiad genera have traditionally been defined on the form or position of the corona. The system proposed by Goyder (2004), uniting a number of small Andean genera under Philibertia, is consistent with the available DNA evidence (Liede-Schumann et al. 2005), and has geographic integrity. Philibertia, in this sense, occurs in Andean or temperate South America, while its nearest relatives Oxypetalum, Araujia and Morrenia have radiated at lower altitude across tropical or subtropical South America east of the Andes, with Tweedia on the western, Chilean slopes. The two species of this alliance most frequently encountered in cultivation are the ‘Cruel Plant’ Araujia sericifera Brot., and the blueflowered Oxypetalum coeruleum (D. Don ex Sweet) Decne. – generally known in cultivation as Tweedia coerulea D. Don ex Sweet. These were illustrated for Curtis’s Botanical Magazine under the names Physianthus albens Mart. and Tweedia versicolor Hook. respectively (Hooker, 1832, 1839). Both of these species are native to north-eastern Argentina. Philibertia itself contains some spectacular plants welldeserving of attention, several of which appear in the centenary issue of Asklepios, just published (Goyder, 2008). The only species I have seen in cultivation is the highly variable P. gilliesii Hook. & Arn. (as P. gracilis D. Don), which was illustrated for Curtis’s Botanical Magazine under the name P. grandiflora Hook. (Hooker, 1837). The recent © The Board of Trustees of the Royal Botanic Gardens, Kew 2008. 245 introduction of P. barbata (Malme) Goyder makes a welcome addition. The material illustrated here was collected as seed in 2000 near the type locality, and grown on in an unheated glasshouse by Harry Hay near Reigate, Surrey. It flowered in 2007. The genus Philibertia Kunth was named in 1819 after J. C. Philibert author of Exercises de botanique à l’usage des commençans, with illustrations by Turpin, published in Paris in 1803. Philibertia barbata is very closely allied to the more widely distributed Argentinian species P. nivea (Griseb.) Goyder, from which it can be distinguished by the absence of long stylar head appendages. A dissected flower of the latter species is shown in Goyder (2008: 28). The description below has been partially abstracted from the lavishly illustrated Genera et Species Plantarum Argentinarum (Meyer, 1944) which was compiled at the Miguel Lillo Institute (LIL) in Tucumán, northern Argentina, where most of the herbarium material is located. Philibertia barbata (Malme) Goyder, Kew Bull. 59: 443 (2004). Type: Argentina, Prov. Jujuy, El Volcán, 24 Feb. 1901, Claren in Kurtz, Hb. Arg. 11759 (Holotype: S.) Mitostigma barbatum Malme, Ark. Bot. 3(1): 10 (1904). DESCRIPTION. Perennial herb or subshrub with stems produced annually and twining to several metres; rootstock not seen. Latex white. Whole plant densely tomentose. Leaves with petiole 1.5–2 cm long; lamina 6–7 × 2–4 cm, triangular or lanceolate-oblong with an attenuate apex and a strongly cordate base, strongly discolorous, tomentose to lanate beneath. Inflorescences extra-axillary, subumbelliform with up to three flowers; peduncle 4–7 cm long long; pedicels 10–15 mm long. Calyx lobes 6–10 mm long, linear. Corolla tomentose outside, bearded within, tube campanulate, c. 5 mm long; lobes 7–9 mm long and 3–4 mm wide at the base, spreading, with recurved apex, purple. Gynostegium on a stipe c. 2 mm long. Gynostegial corona absent. Anther wings 0.5 mm long; anther appendages 2 mm long, enclosing the stylar head, reddish. Corpusculum c. 0.7 mm long, black; translator arms short and broad; pollinia c. 0.6 × 0.4 mm, ovoid. Stylar head white, 2–3 mm long, the bulbous bases narrowing abruptly into two vestigial appendages. Follicles solitary, c. 6 × 1.5–2 cm, oblong, tomentose-pubescent. Seeds c. 4 × 2 mm, flattened and somewhat pyriform in outline. DISTRIBUTION. Known only from the areas around El Volcán and Colalao del Valle in the provinces of Jujuy and Tucumán in northern Argentina. HABITAT. Found on open well-drained rocky slopes in inter-Andean dry valleys at altitudes of 1600–3000 m. Field notes for the specimen illustrated here say it was growing on coarse red scree at c. 2000 m, with Mutisia acuminata Ruiz & Pav., Abromeitiella sp. and Begonia sp. 246 © The Board of Trustees of the Royal Botanic Gardens, Kew 2008. Plate 627 Philibertia barbata CHRISTABEL KING Philibertia barbata. A, sepal, × 4; B, flower, × 2; C, l.s. flower, × 4; D, pollinarium, × 16; E, gynostegium, × 6; F, anther, adaxial surface, × 6. Drawn by Christabel King from CD & R 3029, cultivated by Harry Hay. F LOWERING TIME. Philibertias flower during the rainy season, and all specimens of Philibertia barbata were collected between December and February. REFERENCES Goyder, D.J. (2004). An amplified concept of Philibertia Kunth (Apocynaceae: Asclepiadoideae), with a synopsis of the genus. Kew Bulletin 59: 415–451. Goyder, D.J. (2008). Philibertia from the Andes of Bolivia and Argentina. Asklepios 100: 23–28. Goyder, D.J. (in press). Philibertia (Apocynaceae: Asclepiadoideae) – additional notes and three new species for Bolivia. Kew Bulletin 63. Hooker, W.J. (1832). Physianthus albens. Whitish-leaved Physianthus. Curtis’s Botanical Magazine 59: t. 3201. Hooker, W.J. (1837). Philibertia grandiflora. Large-flowered Philibertia. Curtis’s Botanical Magazine 64: t. 3619. Hooker, W.J. (1839). Tweedia versicolor. Changeable-flowered Tweedia. Curtis’s Botanical Magazine 65: t. 3630. Liede-Schumann, S., Rapini, A., Goyder, D.J. & Chase, M. (2005). Phylogenetics of the New World subtribes of Asclepiadeae (Apocynaceae – Asclepiadoideae): Metastelmatinae, Oxypetalinae and Gonolobinae. Systematic Botany 30: 184–195. Meyer, T. (1944). Asclepiadaceae. In Descole, H.R. (ed.) Genera et species plantarum argentinarum 2: 1–273 & 121 plates. © The Board of Trustees of the Royal Botanic Gardens, Kew 2008. 249