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(Yam family)


The 750 species in 5 genera are found in tropical and warm temperate regions. Typically, they are twining vines arising from underground tubers or rhizomes.

The largest genus, Dioscorea L., is found in tropical and sub-tropical regions. It includes many species of economic importance. Several species, including D. alata L., D. cayennensis Link, and D. trifida L.f. produce edible tubers rich in starch, known as yams. Other species, including D. floribunda Mart. & Gal., D. mexicana Scheidw., and D. villosa L. yield diosgenin, a steroidal sapogenin used in the commercial production of medicinally used steroids.

There have been several reports describing skin irritation following contact with the raw tubers of Dioscorea Plum. ex L. species. This may be attributable to the presence of steroidal saponins which can be removed by washing or boiling. The irritancy of Dioscorea communis (L.) Caddick & Wilkin berries and rhizomes is certainly attributable, in part, to the presence of calcium oxalate raphides. Several species of Dioscorea bear thorns.

Dioscorea alata L.
[syns Dioscorea colocasiifolia Pax, Dioscorea globosa Roxb.]
Asiatic Yam, Greater Yam, Guyana Arrowroot, Purple Yam, Ube, Violet Yam, Water Yam, White Yam, Wild Yam, Winged Yam

The raw tuber is irritant to the mucous membrane of the mouth (Burkill 1935). Application of the juice from the root to the skin produces pruritus and desquamation (Piffard 1881).

Citing an earlier source, Watt & Breyer-Brandwijk (1962) noted that the leaf juice has been used as an application to scorpion sting and the tuber to sores.

[Further information available but not yet included in database]

Dioscorea bulbifera L.
[syn. Dioscorea tenuiflora Schltdl.]
Aerial Yam, Air Potato, Air Yam, Bitter Yam, Cheeky Yam, Parsnip Yam, Potato Yam

Jain et al. (2005), citing an earlier source, noted that in Rajasthan (India) the tubers are used [in an unspecified way] to treat boils, bone fractures, and piles.

[Further information available but not yet included in database]

Dioscorea communis (L.) Caddick & Wilkin
[syns Tamus communis L., Tamus cretica L., Tamus edulis Lowe]
Black Bindweed, Black Bryony, Blackeye Root, Chilblain Berry, Devil's Berries, Isle of Wight Vine, Murrain Berries, Herbe à la Femme Battue, Gemeine Schmerwurz

The fresh rhizome, when scraped or squeezed, yields a colourless mucilaginous sap which has been used as a rubefacient and counter-irritant application in lumbago, rheumatism, and similar disorders (Maheu & Chartier 1927, Wren 1975). The popular names blackeye root and herbe à la femme battue refer to the use of the rhizome as an application to bruises to remove the discolouration (Maheu & Chartier 1927, North 1967).

Both the rubefacient slime from the rhizome and the juice from the berry contain calcium oxalate raphides — measuring an average 450 μm in length and 11 μm in diameter in the berry juice, and an average 250 μm in length and 8 μm in diameter in the slime from the rhizome — which are sharply pointed at both ends. They are responsible for mechanical irritation when rubbed into the skin. In addition, the rhizome contains histamine and saponins, both of which may contribute to the observed skin response following subcutaneous injection by the calcium oxalate raphides (Schmidt & Moult 1983). The irritant effects on the skin may be inhibited by an antihistamine (Holzach & Flück 1951).

In Russian traditional medicine, the rhizome is known as Адамов корень (Adam's root)a, which is dried and powdered, or steamed over boiling water, or used fresh to prepare tinctures and decoctions for external and internal use. The powdered root is used for weeping skin conditions, boils, ulcers, eczema, wounds, bruises, warts, and age spots. The steamed root wrapped in gauze is used as a pain-relieving poultice; alternatively, the tincture (traditionally prepared using vodka) is rubbed into the affected area in the treatment of painful joints, gout, osteochondrosis, rheumatism, sciatica, and polyarthritis.

Whilst the rhizome is recognised as being rubefacient (also being known as огненный корень = fiery root) and therefore counter-irritant, it is also known to cause hypersensitivity (allergic) reactions. Milyavsky (1979) provided a case report of a 46-year old patient who had rubbed an alcoholic tincture of Adam's root onto a painful joint and who subsequently developed a weeping and blistering rash not only on the skin around the painful joint but also on the inner surface of the fingers of her left hand, on the inner right thigh, and on the face where the fingers had touched. A challenge test with 70° proof (35% ABV) alcohol produced no reaction.

Schmidt & Fernández de Corres (1990) described a case of delayed contact sensitivity to black bryony berries that had been used by a 66-year old bronchitic and spondyloarthritic male as a counter-irritant application on his forearm. In this case, various extracts (methanol, acetone, hexane) of the berries produced no reaction on patch testing; but the fresh or lyophilised berries and aqueous extracts produced a delayed vesicular eczematous reaction lasting for more than 120 hours.

The rhizome and particularly the attractive scarlet berries can cause poisoning when ingested. The symptoms are those of an irritant purgative with burning of the mouth and blistering of the skin (North 1967, Lewis & Elvin-Lewis 1977).

The plant has been confused with the white bryony, Bryonia cretica subsp. dioica (Jacq.) Tutin (syn. Bryonia dioica Jacq.) in the family Cucurbitaceae, from which it may be distinguished readily by its lack of tendrils.

[Further information available but not yet included in database]

Dioscorea composita Hemsl.
[syn. Dioscorea tepinapensis Uline ex R.Knuth]

[Information available but not yet included in database]

Dioscorea dumetorum (Kunth) Pax
[syns Dioscorea triphylla G.W.Schimp. ex A.Rich., Helmia dumetorum Kunth]
African Bitter Yam, Cluster Yam, Three-Leaved Yam

According to Watt & Breyer-Brandwijk (1962), the tuber is used in Sekukuniland [in the former Transvaal Province in north-eastern South Africa] as a local application to relieve pain. The application is said to produce a burning sensation.

[Further information available but not yet included in database]

Dioscorea hispida Dennst.
[syn. Dioscorea daemona Roxb.]
Asiatic Bitter Yam, Intoxicating Yam, Wild Yam

Quisumbing (1951) reported that ingestion of raw tubers was a frequent cause of death in the Philippines. However, the tubers are edible after grating, repeated washing and soaking, and boiling (Burkill 1935). The toxicity has been attributed to an alkaloid named dioscorine (Webb 1948a, Webster et al. 1984). Viswanathan & Joshi (1983) noted that "The country brew ‘Khopadi’ prepared from the tubers of D. hispida has been of the source of much tragedy. It causes burning of mouth, nausea, vomiting, drowsiness, tachycardia, coma, respiratory depression and even death."

Citing an earlier source, Jain et al. (2005) noted that in Rajasthan (India), the tubers are used [in an unspecified way] as an antidote in dogbite and to treat boils.

Dioscorea polystachya Turcz.
[syns Dioscorea batatas Decne., Dioscorea doryphora Hance, Dioscorea potaninii Prain & Burkill]
Chinese Yam, Cinnamon Vine, Yamswurz

[Information available but not yet included in database]

Dioscorea septemloba Thunb.
Seven Lobed Yam

The rhizome is the source of the traditional Chinese medicine known as bi xie (萆薢) or mian bixie (绵萆薢), otherwise known as Rhizoma Dioscoreae Septemlobae or as Sevenlobed Yam Rhizome. However, bi xie (萆薢) or mian bixie (绵萆薢) may also refer to Rhizoma Dioscoreae Futschauensis derived from Dioscorea futschauensis Uline ex R.Kunth, Rhizoma Dioscoreae Hypoglaucae (粉萆薢) derived from Dioscorea collettii var. hypoglauca (Palib.) S.J.Pei & C.T.Ting (syn. Dioscorea hypoglauca Palib.), Rhizoma Dioscoreae Spongiosae derived from Dioscorea spongiosa J.Q.Xi, M.Mizuno & W.L.Zhao, Rhizoma Dioscoreae Tokoro (山萆薢) derived from Dioscorea tokoro Makino ex Miyabe, or indeed similar preparations derived from Dioscorea gracillima Miq. or Dioscorea villosa L. (syn. Dioscorea sativa L.). See 中藥詞典 Chinese Herb Dictionary (2010), Chinese Herbal Medicine Database (2015), Chinese Pharmacopoeia (2015).a,b,c

[Further information available but not yet included in database]

Dioscorea transversa R.Br.
[syn. Dioscorea punctata R.Br.]
Common Yam Vine, Long Yam

Maiden (1914) described an acute irritation of the hands and arms in persons washing the pulped tubers from this species. The incident occurred in New South Wales during the production of arrowroot, a starch product. Cleland (1925) also referred to this report.


  • Burkill IH (1935) A Dictionary of the Economic Products of the Malay Peninsula, Vols 1 & 2. London: Crown Agents [doi] [WorldCat] [url] [url-2]
  • Cleland JB (1925) Plants, including fungi, poisonous or otherwise injurious to man in Australia. Medical Journal of Australia ii(15): 443-451 [doi] [doi-2] [url] [url-2]
  • Holzach O, Flück H (1951) Untersuchungen über die Alkaloide und Hautreizstoffe von Tamus communis L. [Studies on the alkaloids and skin irritants of Tamus communis L.]. Pharmaceutica Acta Helvetiae 26(11): 349-359
  • Jain A, Katewa SS, Galav PK, Sharma P (2005) Medicinal plant diversity of Sitamata wildlife sanctuary, Rajasthan, India. Journal of Ethnopharmacology 102(2): 143-157 [doi] [url] [pmid]
  • Lewis WH, Elvin-Lewis MPF (1977) Medical Botany. Plants affecting man's health. New York: John Wiley [WorldCat]
  • Maheu J, Chartier J (1927) Etude de l'herbe dite « à la femme battue » (Tamus communis L.), cause de dermites. [Studies on black bryony (Tamus communis L.), a cause of dermatitis]. Bulletin des Sciences Pharmacologiques 34(10): 566-575 [url] [url-2]
  • Maiden JH (1914) Dioscorea transversa R. Br., a yam, native of New South Wales and Queensland. Agricultural Gazette of New South Wales 25(7): 612 [url] [url-2]
  • Milyavsky AI (1979) Контактный дерматит, вызванный «адамовым корнем». [Contact dermatitis caused by "Adam's root"]. Vestnik Dermatologii i Venerologii (7): 49-50 [url] [pmid]
  • North PM (1967) Poisonous Plants and Fungi in Colour. London: Blandford Press [WorldCat]
  • Piffard HG (1881) A Treatise on the Materia Medica and Therapeutics of the Skin. New York: William Wood & Company [WorldCat] [url] [url-2]
  • Quisumbing E (1951) Medicinal Plants of the Philippines. Technical Bulletin 16, Philippines Department of Agriculture and Natural Resources. Manila, Philippine Islands: Manila Bureau of Printing [WorldCat]
  • Schmidt RJ, Moult SP (1983) The dermatitic properties of black bryony (Tamus communis L.). Contact Dermatitis 9(5): 390-396 [doi] [url] [url-2] [pmid]
  • Schmidt RJ, Fernández de Corres L (1990) An unusual case of delayed contact sensitivity to black bryony berries (Tamus communis L.). Contact Dermatitis 23(4): 260-261 [doi] [url] [url-2]
  • Viswanathan N, Joshi BS (1983) Toxic constituents of some Indian plants. Current Science 52(1): 1-8 [url] [url-2]
  • Watt JM, Breyer-Brandwijk MG (1962) The Medicinal and Poisonous Plants of Southern and Eastern Africa. Being an account of their medicinal and other uses, chemical composition, pharmacological effects and toxicology in man and animal, 2nd edn. Edinburgh: E & S Livingstone [doi] [WorldCat] [url] [url-2]
  • Webb LJ (1948a) Guide to Medicinal and Poisonous Plants of Queensland. Bulletin No. 232. Melbourne, Victoria: Council for Scientific and Industrial Research [doi] [url]
  • Webster J, Beck W, Ternai B (1984) Toxicity and bitterness in Australian Dioscorea bulbifera L. and Dioscorea hispida Dennst. from Thailand. Journal of Agriciltural and Food Chemistry 32(5): 1087-1090 [doi] [url] [url-2]
  • Wren RC (1975) Potter's New Cyclopaedia of Botanical Drugs and Preparations. (Re-edited and enlarged by Wren RW). Bradford, Devon: Health Science Press [WorldCat] [doi] [url] [url-2]
  • [ + 11 further references not yet included in database]

Richard J. Schmidt

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