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Dioscorea sansibarensis

(Zanzibar Yam)

Overview

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Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in English:

Zanzibar Yam

Common Names in German:

Sansibar-Yams

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.[1]

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) .[2]

Physical Description

Species Dioscorea sansibarensis

Plants tuberous ; tubers buried just below soil surface, irregularly lobed , globose . Stems twining counterclockwise , climbing to more than 7 m , terete , grooved , or weakly angled with variable number of longitudinal ridges raised less than 1 mm adaxially, producing axillary bulbils frequently greater than 5 cm diam. in leaf axils . Leaves alternate at basal nodes, opposite distally, 6-27 × 7-42 cm; petiole 6-20 cm, as long as or slightly longer than blade , base clasping , basal lobes stipulate , 1-8 mm wide; blade 7-11-veined, reniform to somewhat deltate, glabrous , margins irregularly 3-5-lobed, apex conspicuously caudate . Staminate inflorescences 1-2(-4) per axil, spicate or terminally paniculate , cymose ; cymes subsessile , bearing (1-) 2-4 flowers subtended by ovate bracteoles, internodes ca. 1 cm; rachis 20-40 cm, subtended by ovate bracts ca. 1 mm. Pistillate inflorescences 1-3 per axil, to 80 cm, internodes 2-2.5 cm. Staminate flowers: perianth yellowish; tepals in 2 similar whorls, narrowly spreading at anthesis , lanceolate, 3-6 mm; fertile stamens 6 in 2 subequal whorls; anthers less than ½ length of filaments , thecae distinct , not spreading. Pistillate flowers: perianth white with purple veins; tepals as in staminate flowers ; staminodes 6, smaller than fertile stamens; style branches irregularly 2-fid. Capsules not reflexed at maturity, longer than wide. Seeds bilaterally winged . [source]

Dioscorea sansibarensis, an ornamental species native to tropical Africa, is widely cultivated for its large, unusually shaped leaves. It has recently been reported growing amongst native vegetation in Miami-Dade and Collier counties in southern Florida. Axillary bulbils shed from mature plants were observed to be growing vigorously. Both the tubers and axillary bulbils of this species are toxic . [source]

Habit: Forb/herb, Vine

Size/Age/Growth

Size: 20-30' tall.

Habitat

Roadsides, hammocks , swamps ; 0 m ; introduced [3].

Biology

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Reproduction

Duration: Perennial

Growth

Temperature: Cold Hardiness: 10b, 11. (map)

Taxonomy

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Synonyms

D. macroura Harms • D. welwitschii Rendle • Dioscorea macabiha Jumelle & H. Perrier

Notes

Publishing author : Pax Publication : Bot. Jahrb. Syst. 15(2): 146 1892 [5 Apr 1892]

Name Status: Accepted Name .

Last scrutiny: 21-Jun-2005

Similar Species

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Members of the genus Dioscorea

ZipcodeZoo has pages for 47 species, subspecies, varieties, forms, and cultivars in this genus:

D. alata (Purple Yam) · D. altissima (Dunguey) · D. bulbifera (Aerial Yam) · D. bulbifera var. bulbifera (Air Potato) · D. cayenensis (Yellow Guinea Yam) · D. cayennensis (Yellow Guinea Yam) · D. cirrhosa (Dyeing Yam (Philippines)) · D. communis (Lady´s-Seal) · D. composita (Yam) · D. convolvulacea (Yam) · D. cylindrica (Wild Yam) · D. deltoidea (Wild Yam) · D. discolor (Ornamental Yam) · D. dumetorum (Bitter Yam) · D. elephantipes (Elephants Foot) · D. esculenta (Chinese Yam) · D. floribunda (Yam) · D. floridana (Florida Yam) · D. glabra (Chinese Yam) · D. hemicrypta (Dioscorea) · D. hispida (Intoxicating Yam) · D. japonica (Glutinous Yam) · D. kamoonensis (Kamoon Yam) · D. macrostachya (Yam) · D. macrostachys (Elephants Foot) · D. mexicana (Barbasco) · D. nummularia (Yam) · D. oppositifolia (Chinese Wild Yam) · D. pentaphylla (Five-Leaf Yam) · D. pilosiuscula (Bulbous Yam) · D. polygonoides (Mata Gallina) · D. praehensilis (Bush Yam) · D. prazeri (Wild Yam) · D. preussii (Preuss' Dioscorea) · D. purpurea (Podicherry Sweet Potato) · D. quaternata (Fourleaf Wild-Yam) · D. rotundata (Guinea Yam) · D. sagittata (Five-Leaved Yam) · D. sagittifolia (Wild Congo Yam) · D. sansibarensis (Zanzibar Yam) · D. septemloba (Seven-Lobed Yam) · D. spiculiflora (Yam) · D. sylvatica (Wild Yam) · D. tokoro (Mountain Yam) · D. tomentosa (Thorny Yam) · D. trifida (Indian Yam) · D. villosa (Colic Root)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 23, 2007:

Identifiers

Footnotes

  1. 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. [back]
  2. "Dioscorea". in Flora of China Vol. 24 Page 276. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  3. "Dioscorea sansibarensis". in Flora of North America Vol. 26 Page 481, 485. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/15/2012