dcsimg
8.6025999184.130x130
Life » » Plants » » Yam family »

Dioscorea villosa L.

Brief Summary

    Dioscorea villosa: Brief Summary
    provided by wikipedia

    Dioscorea villosa is a species of a twining tuberous vine that is native to eastern North America. It is common and widespread in a range stretching from Texas and Florida north to Minnesota, Ontario and Massachusetts. It is currently on the United Plant Savers "At Risk" list. UpS is an organization concerned with the preservation of endangered medicinal plants on the territory of North America.[1]

    Dioscorea villosa has been found by scientists to contain diosgenin, a phytoestrogen. Phytoestrogens - the plant hormones - have been shown to interact with hormone receptors in human bodies.[2][3] Wild Yam and its extract has been promoted as a medicine for a variety of purposes, including cancer prevention and the treatment of Crohn's disease and whooping cough. It can be found in creams and other natural supplements.

    According to the American Cancer Society, the claims are false and there is no evidence to support these substances being either safe or effective.

    In traditional Russian herbal medicine, saponin extracts from the roots of various varieties of wild yam are used as an anticoagulant, antisclerotic, antispasmodic, cholagogue, depurative, diaphoretic, diuretic and a vasodilator.

Comprehensive Description

    Dioscorea villosa
    provided by wikipedia

    Dioscorea villosa is a species of a twining tuberous vine that is native to eastern North America. It is common and widespread in a range stretching from Texas and Florida north to Minnesota, Ontario and Massachusetts.[1][2][3][4] It is currently on the United Plant Savers "At Risk" list. UpS is an organization concerned with the preservation of endangered medicinal plants on the territory of North America.[1]

    Dioscorea villosa has been found by scientists to contain diosgenin, a phytoestrogen. Phytoestrogens - the plant hormones - have been shown to interact with hormone receptors in human bodies.[2][3] Wild Yam and its extract has been promoted as a medicine for a variety of purposes, including cancer prevention and the treatment of Crohn's disease and whooping cough. It can be found in creams and other natural supplements.

    According to the American Cancer Society, the claims are false and there is no evidence to support these substances being either safe or effective.[5]

    In traditional Russian herbal medicine, saponin extracts from the roots of various varieties of wild yam are used as an anticoagulant, antisclerotic, antispasmodic, cholagogue, depurative, diaphoretic, diuretic and a vasodilator.[6]

    References

    1. ^ a b Kew World Checklist of Selected Plant Families
    2. ^ Flora of North America
    3. ^ Govaerts, R., Wilkin, P. & Saunders, R.M.K. (2007). World Checklist of Dioscoreales. Yams and their allies: 1-65. The Board of Trustees of the Royal Botanic Gardens, Kew.
    4. ^ Biota of North America Program, 2013 county distribution map
    5. ^ "Wild Yam". American Cancer Society. November 2008. Retrieved 21 September 2013..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
    6. ^ Zevin, Igor Vilevich. A Russian Herbal. 1997. Rochester, Vermont: Healing Arts Press. p.146-47.

Distribution

    Distribution
    provided by eFloras
    Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.

Morphology

    Comments
    provided by eFloras
    Dioscorea villosa is a highly polymorphic species, exhibiting complex patterns of variation across its geographic range. Characters that have been used previously to delineate taxonomic boundaries within this complex—pubescence, glaucousness, rhizome thickness and shape, length of internodes within the inflorescence, arrangement of proximal leaves, geometry of the stem, and fruit and seed size/shape—fail when individuals from all parts of the range and specimens representing both apical and basal portions of single stems can be examined. At its morphological extremes, D. villosa comprises 1) small vines with tightly congested inflorescences, winged stems, and variously pubescent leaves, occurring in bogs and branch swamps; and 2) robust plants, rigid at the base, the proximal leaves verticillate with large, glaucous blades, from the axils of which arise lax spikes or panicles, inhabiting rocky, upland woods and steep talus slopes. As one ascends from the Atlantic Coastal Plain through the Appalachians, continuing westward to the Great Lakes region, south to the Ozarks, and east to the branch swamps of Georgia, particular morphologies are associated with particular ecological conditions, independent of geography. As well as the morphological extremes, every intermediate condition of leaf, stem, and inflorescence architecture can be found, in all combinations, and variation may be encountered even within individual plants. What sort of genetic structure underlies these patterns of morphological diversity remains an open question. That there is a significant degree of genetic variability within the complex is evident from the chromosome counts thus far reported. Further research is needed to shed light on patterns of gene flow in the complex, and garden studies would be instructive as to the limits of individual plasticity. At present, I can find no natural gaps in the variation between the plants that have been called (albeit ambiguously; see H. H. Bartlett 1910) D. villosa and those called D. quaternata, and therefore I am treating the complex as a single species.
    Description
    provided by eFloras
    Plants rhizomatous; rhizomes brownish, unbranched or highly branched, linear to irregularly contorted, 0.5–1.5 cm or more diam., nodes not articulate. Stems longitudinally grooved or sometimes narrowly winged, usually terete in cross section, 1–7 m, ± rigid proximally, or flexible, glabrous or rarely with sparse pubescence, wings when present less than 1 mm and stems polygonal. Leaves alternate, subopposite, subverticillate, or in verticels of 3–7 proximally, due to suppression of proximal inter-nodes (esp. in woodland understory), always alternate distally, 3–13 × 2–13 cm, ca. as long as wide; petiole ridged or narrowly winged, 3–14 cm, glabrous or puberulent at pulvinus, base not clasping; blade green to ± glaucous, (7–)9–11-veined, ovate-cordate, abaxial surface sometimes ± glandular, or sparsely or sometimes densely pubescent to glabrous, base with sinus rounded, acute, or ± truncate basally, margins entire or repand, apex acute to acuminate, occasionally mucronate. Staminate inflorescences solitary in leaf axils, rarely terminal, spicate or branched; cymes sessile, bearing 1–3 sessile flowers, braceolate, internodes between cymes 1–8 mm, bracteoles ca. 1 mm; rachis 2–30 cm, secondary axes to 15 cm, robust plants occasionally branched to third order, axes subtended by linear-lanceolate bracts 1–3 mm. Pistillate inflorescences solitary, 4–18-flowered, 4–20 cm, internodes 6–12 mm. Staminate flowers: perianth greenish white, appearing darker in some specimens due to presence of irregularly distributed tannin crystals, rotate-campanulate to funnelform, 1–2(–3) mm diam.; tepals ± glandular, ovate-elliptic, margins hyaline, apex rounded or acute; stamens in 2 subequal whorls, erect; anthers ca. ½ length of filaments, thecae distinct, widely spreading. Pistillate flowers: perianth greenish white, rotate-campanulate, 2–4 mm wide; tepals as in staminate flowers; staminodes 6, differentiated into anthers and filaments, less than 1/2 length of fertile stamens. Capsules greenish gold, ovoid to obovoid to obreniform, 1–3 × 1–3.5 cm, varying continously in size, occasionally ± glaucous. Seeds generally 2 per locule, rarely 1, 5–18 mm. 2n = 20, 36, 54, 60.

Diagnostic Description

    Synonym
    provided by eFloras
    Dioscorea cliffortiana Lamarck; D. glauca Muhlenberg ex Bartlett; D. hexaphylla Rafinesque; D. hirticaulis Bartlett; D. longifolia Rafinesque; D. lloydiana E. H. L. Krause; D. megaptera Rafinesque; D. paniculata Michaux; D. paniculata var. glabrifolia Bartlett; D. pruinosa Kunth; D. quaternata J. F. Gmelin; D. quaternata var. glauca (Muhlenberg ex Bartlett) Fernald; D. quinata J. F. Gmelin; D. repanda Rafinesque; D. villosa var. glabra Lloyd; D. villosa subsp. glabrifolia (Bartlett) W. Stone; D. villosa var. glabrifolia (Bartlett) S. F. Blake; D. villosa subsp. glauca (Muhlenberg ex Bartlett) R. Knuth; D. villosa subsp. hirticaulis (Bartlett) R. Knuth; D. villosa var. hirticaulis (Bartlett) H. E. Ahles; D. villosa subsp. paniculata (Michaux) R. Knuth; D. villosa subsp. quaternata (J. F. Gmelin) R. Knuth; D. villosa var. vera Prain & Burkill; D. waltheri Desfontaines

Habitat

    Habitat
    provided by eFloras
    Borders of bogs, swamps, marshes, river and lake margins, creek bottoms, sandy or rocky soils, moist or dry woods, hammocks, thickets, limestone or talus slopes, roadsides; 0--1500m.

Cyclicity

    Flowering/Fruiting
    provided by eFloras
    Flowering mid spring--summer; fruiting late summer.