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Dioscorea macrostachya

(Yam)

Common Names

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Common Names in English:

Yam

Description

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Family Dioscoreaceae

Herbs twining or woody vines , rarely erect , small herbs. Rootstock rhizomatous or tuberous . Stem twining to left or right , pubescent or glabrous , sometimes prickly. Leaves alternate or opposite, petiolate , simple or palmately compound , basal veins 3--13, interstitial veins reticulate; leaflets of palmately compound leaves often ovate or lanceolate. Flowers usually unisexual (when plants dioecious, rarely monoecious), sometimes bisexual , solitary, clustered, or in cymules , these in a spike, raceme , or thyrse , these sometimes grouped into panicles. Male flowers: perianth lobes 6, in 2 whorls, basally connate or free ; stamens 6, sometimes 3 reduced to staminodes or absent, inserted on perianth or receptacle; ovary rudimentary or absent. Female flowers: similar to male ones; staminodes 3, 6, or absent; ovary inferior, 3-loculed, ovules usually 2 per locule (more than 2 in a few small genera), placentation axile ; styles 3, free. Fruit a capsule, berry, or samara. Seeds with a membranous wing or not; endosperm present; embryo small.

About nine genera and 650 species: widely distributed in tropical and temperate regions , especially in tropical America; one genus and 52 species (21 endemic, two introduced ) in China.Chih-chi Ting & Michael G. Gilbert "Dioscoreaceae". in Flora of China Vol. 24 Page 276. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.

Genus Dioscorea

Herbs twining . Rootstock rhizomatous or tuberous , variable in color, shape , chemical constituents, and depth in ground . Bulblets axillary or absent. Leaves alternate or opposite, petiolate , simple or palmately compound , basal veins 3--9. Flowers unisexual (plants dioecious, rarely monoecious), arranged spirally in axillary, usually elongate spikes or racemes , or in small cymules in ± spikelike thyrses , these often several together, sometimes gathered into a terminal or axillary panicle by reduction of subtending leaves. Male flowers: stamens 6, 3 sometimes reduced to staminodes or absent. Female spikes 3.5--10 cm, few flowered. Female flowers: staminodes 3, 6, or absent. Capsule 3-winged, dehiscent apically at maturity. Seeds with a membranous wing.

More than 600 species: widely distributed in tropical and temperate regions ; 52 species (21 endemic, two introduced ) in China.

Dioscorea is a genus of great economic value, including important food plants. Several species are widely cultivated in many cultivars (including Dioscorea alata D. esculenta D. japonica and D. polystachya), while other, wild species are valuable famine foods. Other species are sources of drugs both in traditional Chinese and Western medicine (notably D. nipponica and D. zingiberensis which are major sources of steroid precursors) ."Dioscorea". in Flora of China Vol. 24 Page 276. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Place of publication : Pl. hartw. 73. 1841

Name verified on 12-May-1995 by ARS Systematic Botanists. Last updated: 12-May-1995

Similar Species

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Members of the genus Dioscorea

There are approximately 970 species in this genus. Here are just 100 of them:

D. abysmophila · D. abyssinica · D. acanthogene · D. acarophyta · D. acerifolia · D. acrotheca · D. aculeata · D. acuminata · D. acutangula · D. acutata · D. acutifolia · D. adenantha · D. adenocarpa · D. aesculifolia · D. affinis · D. aguilarii · D. ainensis · D. alata (Purple Yam) · D. alatipes · D. albanica · D. albicaulis · D. albinervia · D. alboholosericea · D. alta · D. althaeoides · D. altissima (Dunguey) · D. amaranthifolia · D. amaranthoides · D. amaranthoides var. elegantula · D. amarantoides · D. amarantoides var. crumenigera · D. amarantoides var. metallica · D. amazonum · D. amoena · D. analalavensis · D. ancachsensis · D. anchiatasi · D. anchietae · D. anconensis · D. andina · D. andongensis · D. andromedusae · D. angolensis · D. anguina · D. angulata · D. angusta · D. angustiflora · D. angustifolia · D. anomala · D. antaly · D. anthropophagorum · D. antucoana · D. apiculata · D. apurimacensis · D. arachidna · D. araucana · D. arcuata · D. arcuatinervis · D. argyrogyna · D. arifolia · D. aristolochiaefolia · D. aristolochiifolia · D. armata · D. asclepiadea · D. aspera · D. aspersa · D. asperula · D. asteriscus · D. astrostigma · D. atrescens · D. atropurpurea · D. auriculata · D. axilliflora · D. bahiensis · D. baicalensis · D. bako · D. balcanica · D. balsapuertensis · D. bangii · D. banzhuana · D. barclayi · D. bartlettii · D. basiclavicaulis · D. baya · D. beccariana · D. beecheyi · D. belizensis · D. belophylla · D. belophylloides · D. bemandry · D. bemarivensis · D. benthamii · D. berenicea · D. bermejensis · D. bernoulliana · D. berteroana · D. besseriana · D. beyrichii · D. bicolor · D. biformifolia

Bibliography

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More Info

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 23, 2007:

Identifiers

Footnotes

Last Revised: 2008-09-29