Dioscoreaceae

Taxonomy

Family name: Dioscoreaceae R. Brown

Synonym(s): Avetraceae Takht.; Stenomeridaceae J. Agardh, nom. cons.; Tamaceae Bercht. & J. Presl; Trichopodaceae Hutch., nom. cons.

Common name(s): yam family

*Number of genera/species: 9/175

List of genera records in GRIN-Global

Disseminule

fruit or seed

Description

Fruit usually dehiscentdehiscent:
(v. dehisce) splitting open at maturity to release contents (of a fruit)
, capsulecapsule:
a dry, dehiscent fruit formed by two or more carpels
(denticidal or loculicidalloculicidal:
type of capsular dehiscence, opening longitudinally through the locules (compare septicidal)
), rarely indehiscentindehiscent:
not opening on its own, as in a fruit
, berryberry:
an indehiscent, fleshy fruit with one or a few to many seeds. The flesh may be homogenous throughout. Or, if the outer part is hard, firm, or leathery, referred to as an hesperidium. Septa are present in some, and the seeds may be arillate or with a fleshy testa.
(red, 1–6 seeded in Tamus) or samarasamara:
a winged, indehiscent, dry fruit containing a single (rarely two) seed(s)
(Rajana), 10–70 mm long, globoseglobose:
3D shape—more or less spherical
to triangulartriangular:
2D shape—three relatively straight sides with distinct corners; more angular than teardrop-shaped
, sometimes three-winged, tereteterete:
approximately circular in cross section; width and thickness approximately equal
or angledangled:
2D shape—having sides that meet at acute or obtuse angles  
in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, one seeded (berry, samarasamara:
a winged, indehiscent, dry fruit containing a single (rarely two) seed(s)
) to many seeded. SepalsSepals:
a member of the outer envelope of a flower (calyx)
sometimes persistent. Pericarppericarp:
fruit wall or fruit coat
black, brown, green, orange, purple, red, yellow, shinyshiny:
uniformly reflecting a high proportion of incident light at all angles
or dulldull:
reflecting only a low proportion of incident light, with no apparent sheen
, leatheryleathery:
texture—moderately thick, tough, and very pliable
to fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
or membranousmembranous:
texture—extremely thin, pliable, and fairly tough
, smooth or ridgedridged:
surface relief—raised, thick ridges, sharp edged or rounded, usually in a series that may cover the entire surface
, sometimes pubescentpubescent:
surface relief—bearing hairs
.

Seed globoseglobose:
3D shape—more or less spherical
to angularangular:
2D shape—having sides that meet at acute or obtuse angles  
, tereteterete:
approximately circular in cross section; width and thickness approximately equal
to flattened in transectiontransection:
a cross section; representing a plane made by cutting across an organ at a right angle to its length
, 4–40 mm, rapheraphe:
a ridge or seam on the seed coat, formed by the portion of the funiculus united to the ovule wall in longitudinally curved ovules
sometimes conspicuous. Seeds with wings at one or both ends or surrounding seeds, or without wings. Seed coat many layered, red to yellow-brown, dulldull:
reflecting only a low proportion of incident light, with no apparent sheen
, leatheryleathery:
texture—moderately thick, tough, and very pliable
, variously sculptured from wrinkledwrinkled:
surface relief—shallow, irregular folds and furrows covering the surface; appearing overall though crumpled and then spread out
to papillatepapillate:
surface relief—bearing minute, distinct, broad-based projections, tapering to a rounded apex
, sometimes pubescentpubescent:
surface relief—bearing hairs
.

Embryo small, well developed, linearlinear:
(shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide
or capitatecapitate:
head-shaped; abruptly enlarged on one end to a relatively short, terminal portion
, straight, basalbasal:
at or pertaining to the point of attachment; (of embryo) embryo occupies one end of the seed
. Endospermendosperm:
nutritive starch- and oil-containing tissue present in many seeds
copious, cartilaginouscartilaginous:
texture—firm, dense, tough, somewhat pliable, and resilient, like cartilage
, fleshyfleshy:
texture—fairly firm and dense, juicy or at least moist, and easily cut
or hard, smooth, pittedpitted:
surface relief—surface with small depressions in which the areas between the hollows do not take on the appearance of a true reticular net
, or ruminateruminate:
testa or seed coat folded into the endosperm
.

Identification features

Fruit
Type	denticidal denticidal: type of capsular dehiscence, fruit opening by a series of apical teeth or loculicidalloculicidal: type of capsular dehiscence, opening longitudinally through the locules (compare septicidal) capsulecapsule: a dry, dehiscent fruit formed by two or more carpels , rarely berry
Size range	10–70 mm long
Shape(s)	triangular, ellipsoidellipsoid: 3D shape—elliptic , oblongoblong: 2D shape—much longer than broad with nearly parallel sides, corners are rounded , lanceolatelanceolate: 2D shape—lance-shaped; much longer than wide, with widest point below the middle, tapering to the apex (compare oblanceolate) , ovoidovoid: 3D shape—ovate , globoseglobose: 3D shape—more or less spherical , heart-shaped
Texture	fleshy, membranousmembranous: texture—extremely thin, pliable, and fairly tough , chartaceouschartaceous: =papery, papyraceous , leathery
Surface relief	smooth or ridgedridged: surface relief—raised, thick ridges, sharp edged or rounded, usually in a series that may cover the entire surface , pubescent
Color(s)	black, brown, green, orange, purple, red, yellow
Unique features	Three-winged or angledangular: 2D shape—having sides that meet at acute or obtuse angles capsules often with winged seeds. Or, samarassamara: a winged, indehiscent, dry fruit containing a single (rarely two) seed(s) .
Seed
Size range	4–40 mm long
Shape(s)	polygonal, C-shapedC-shaped: 2D-shape—semiannulate, curved into the shape of the letter 'C' , oblongoblong: 2D shape—much longer than broad with nearly parallel sides, corners are rounded , globoseglobose: 3D shape—more or less spherical , ovoidovoid: 3D shape—ovate , curvedcurved: (of embryo) linear embryo is curved into an arch or horseshoe with the ends far apart , reniformreniform: 2D or 3D shape—kidney-shaped , ellipsoidellipsoid: 3D shape—elliptic , straight, irregular
Surface relief	wrinkled, reticulatereticulate: surface relief—netted, raised walls or concave grooves forming a net-like surface pattern with flat, concave, or convex interspaces , ribbedribbed: surface relief—wide, prominent, linear ridges that are generally rounded and longitudinally situated on the surface , ridgedridged: surface relief—raised, thick ridges, sharp edged or rounded, usually in a series that may cover the entire surface , striatestriate: surface relief—having fine, parallel lines, grooves or ridges , groovedgrooved: surface relief—linear depressions that may be single or form a series of grooves over the surface , papillate
Color(s)	brown, red
Unique features	Seeds often winged with conspicuous rapheraphe: a ridge or seam on the seed coat, formed by the portion of the funiculus united to the ovule wall in longitudinally curved ovules and small, well developed, basalbasal: at or pertaining to the point of attachment; (of embryo) embryo occupies one end of the seed embryos.
Other
Embryo	small, well developed, linearlinear: (shape) long, narrow, and uniform in width; (of embryo) embryo is straight and much longer than wide or capitatecapitate: head-shaped; abruptly enlarged on one end to a relatively short, terminal portion , straight, basal
Nutritive tissuenutritive tissue: tissue within the seeds that nourishes the developing embryo; such as endosperm, perisperm, or chalazosperm in angiosperms; megagametophyte in gymnosperms	endosperm endosperm: nutritive starch- and oil-containing tissue present in many seeds copious, cartilaginouscartilaginous: texture—firm, dense, tough, somewhat pliable, and resilient, like cartilage , fleshyfleshy: texture—fairly firm and dense, juicy or at least moist, and easily cut or hard, smooth, pittedpitted: surface relief—surface with small depressions in which the areas between the hollows do not take on the appearance of a true reticular net , or ruminateruminate: testa or seed coat folded into the endosperm .

Distribution

Pantropical, with one genus, Tamus, occurring in warm-temperate regions.

Distribution map courtesy of Angiosperm Phylogeny Website.

References

Baskin and Baskin 2021Baskin and Baskin 2021:
Baskin C and Baskin J. 2021. Relationship of the lateral embryo (in grasses) to other monocot embryos: A status up-grade. Seed Science Research 31 (3): 199-210. doi:10.1017/S0960258521000209; Burkill 1948Burkill 1948:
Burkill IH. 1951. Dioscoreaceae. Flora Malesiana Ser. 1, Spermatophyta 4 (1): 293ndash;335.; Dahlgren et al. 1985Dahlgren et al. 1985:
Dahlgren RMT, Clifford HT, and Yeo PF. 1985. The families of the monocotyledons: structure, evolution, and taxonomy. Springer-Verlag, Berlin. 520 pp.; George 1986George 1986:
George AS. 1986. Flora of Australia. Volume 46. Iridaceae to Dioscoreaceae. Australian Government Publishing Service, Canberra Australia. 247 pp.; Kirkbride et al. 2006Kirkbride et al. 2006:
Kirkbride JH, Jr, Gunn CR, and Dallwitz MJ. 2006. Family guide for fruits and seeds, vers. 1.0. Accessed September 2020ndash;January 2022. URL: https://nt.ars-grin.gov/seedsfruits/keys/frsdfam/index.cfm .; Kubitzki et al. 1990+Kubitzki et al. 1990+:
Kubitzki K et al., eds. 1990+. The families and genera of vascular plants. 7+ vols. Berlin etc.; Milne-Redhead 1975Milne-Redhead 1975:
Milne-Redhead E. 1975. Dioscoreaceae. In: Polhill RM, ed. Flora of Tropical East Africa. Vol 56. Crown Agents for Oversea Governments and Administrations, London UK. 25 pp.; Stevenson and Loconte 1995Stevenson and Loconte 1995:
Stevenson DW and Loconte H. 1995. A cladistic analysis of monocot families. In: Rudall PJ, Cribb PJ, Cutler DF, and Humphries CJ, eds. Monocotyledons: Systematics and Evolution. Royal Botanic Gardens, Kew.; Wilkin 2001Wilkin 2001:
Wilkin P. 2016. Dioscoreaceae of South-Central Africa. Kew Bulletin 56 (2): 361ndash;404. https://doi.org/10.2307/4110963; Zhengyi et al. 2004+Zhengyi et al. 2004+:
Zhengyi W, Raven PH, and Deyuan H. 2004+. Flora of China [online]. 25 vols. Science Press, Beijing China amp; Missouri Botanical Garden, St. Louis USA. Accessed January-December 2021. http://flora.huh.harvard.edu/china/

*The number of genera and species is based on Christenhusz and Byng 2016Christenhusz and Byng 2016:
Christenhusz MJM and Byng JW. 2016. The number of known plant species in the world and its annual increase. Phytotaxa 261 (3): 201ndash;217. https://doi.org/10.11646/phytotaxa.261.3.1, which may differ from the number of genera in GRIN-Global.