Dioscoreaceae

Water yam Dioscorea alata, photographed by Bryan Harry.

Belongs within: Liliales.

The Dioscoreaceae is a pantropical family mostly composed of tuberous vines, some species of which (in the genus Dioscorea) are grown as food plants.

Characters (from L. Raz):Vines (sometimes herbs), geophytes perennating from fleshy rhizomes or tubers. Stems renewed annually or occasionally persisting for more than a single growing season, twining-climbing, procumbent, or seldom erect; vascular bundles commonly arranged in 2 concentric circles. Leaves alternate, opposite, or whorled at basal nodes; blades simple or occasionally digitately compound, typically cordate, reticulate-veined; principal veins arcuate, ascending from base to apex; margins entire or sometimes palmately lobed; stipules absent, rarely stipulate, never with tendrils; petioles typically with distinct pulvinus at each end. Inflorescences axillary, solitary or in fascicles of 2–7, branched and paniculate, or unbranched and spicate or racemose, ultimate inflorescence unit cymose, sessile or pedunculate, often reduced to 1 flower. Flowers unisexual, staminate and pistillate flowers on different plants, rarely staminate and pistillate flowers on same plant or bisexual; perianth epigynous, rotate, campanulate, or funnelform; tepals 6, petaloid, in 2 similar whorls of 3, connate at least basally; stamens 6, in 2 whorls of 3, inner whorl sometimes sterile or absent; filaments distinct (sometimes connate basally or completely into tube), inserted at base of perianth; anthers 2-locular, tetrasporangiate, dehiscing by longitudinal slits, thecae distinct or sometimes connate, rarely divided by a long-appendiculate connective; pistils 3; ovary (1–)3-locular, ovules anatropous, 2(–many) per locule, placentation axile or parietal; styles 3, ± distinct. Fruits capsular, rarely baccate or samarate, dehiscence loculicidal. Seeds flattened or globose, winged or unwinged, embryo small, endosperm copious, starchless.

<==Dioscoreaceae
    |--Epipetrum YY22
    |--Rajania ovata J87
    |--Testudinaria YY22
    |--Borderea YY22
    |--Higinbothamia YY22
    |--Tamus communis DS04
    |    |--T. c. ssp. communis PT98
    |    `--T. c. ssp. cretica PT98
    `--Dioscorea DS04
         |--D. aculeata C55
         |--D. alata C55
         |--D. belophylla HU08
         |--D. bulbifera C55
         |--D. deltoides C55
         |--D. glabra P03
         |--D. hamiltonii SR07
         |--D. hispida P03
         |--D. nummularia H03
         |--D. pentaphylla C55
         |--D. polygonoides DS04
         |--D. retusa DS04
         `--D. villosa EBS98

*Type species of generic name indicated

REFERENCES

[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.

[DS04] Davis, J. I., D. W. Stevenson, G. Petersen, O. Seberg, L. M. Campbell, J. V. Freudenstein, D. H. Goldman, C. R. Hardy, F. A. Michelangeli, M. P. Simmons, C. D. Specht, F. Vergara-Silva & M. Gandolfo. 2004. A phylogeny of the monocots, as inferred from rbcL and atpA sequence variation, and a comparison of methods for calculating jackknife and bootstrap values. Systematic Botany 29 (3): 467-510.

[EBS98] Elliott, K. J., L. R. Boring & W. T. Swank. 1998. Changes in vegetation structure and diversity after grass-to-forest succession in a southern Appalachian watershed. American Midland Naturalist 140: 219-232.

[H03] Heads, M. 2003. Ericaceae in Malesia: Vicariance biogeography, terrane tectonics and ecology. Telopea 10 (1): 311-449.

[HU08] Hore, U., & V. P. Uniyal. 2008. Diversity and composition of spider assemblages in five vegetation types of the Terai Conservation Area, India. Journal of Arachnology 36 (2): 251-258.

[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State Museum – Biological Sciences 32 (1): 1-136.

[PT98] Panitsa, M., & D. Tzanoudakis. 1998. Contribution to the study of the Greek flora: Flora and vegetation of the E Aegean islands Agathonisi and Pharmakonisi. Willdenowia 28: 95-116.

[P03] Paul, T. K. 2003. Botanical observations on the Purulia pumped storage hydropower project area, Bagmundi Hills, Purulia district, West Bengal. Bulletin of the Botanical Survey of India 45 (1-4): 121-142.

[SR07] Sankar, R. V., K. Ravikumar, N. M. Ganesh Babu & D. K. Ved. 2007. Botany of Anapady MPCA, Palghat district, Kerala with special emphasis on species of conservation concern. Bulletin of the Botanical Survey of India 49 (1-4): 165-172.

[YY22] Yampolsky, C., & H. Yampolsky. 1922. Distribution of sex forms in the phanerogamic flora. Bibliotheca Genetica 3: 1-62.

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