Dioscorea
Common Schmerwurz ( Dioscorea communis)
Yams ( Dioscorea ), also known as yam or yam, are a genus of the family of Yamswurzelgewächse ( Dioscorea ). Yams is distributed mainly in the tropics. The only native species in Central Europe, the black bryony ( Dioscorea communis) and the Balkan Schmerwurz ( Dioscorea balcanica ). The genus is named after Pedanios Dioscorides, a Greek physician of the 1st century.
Description
Yam species grow as twining, perennial herbaceous plants. They form root nodules as outlasting which may be very different in size, shape, color, material content and depth in the earth. The stalked leaves are simple or compound.
The flowers are always unisexual, the plants are usually dioecious ( dioecious ), rarely monoecious ( monoecious ). The male flowers have six or three stamens.
They form triple winged seed capsules. The seeds have membranous wings.
Use
Some types and their selection forms are useful plants, both as an important food crops as well as medicinal plants. Many types of yams are grown as food for its edible tubers.
In the most widely grown type the underground tubers reach a length of up to 2 meters, its taste is sweet and similar to chestnuts and potatoes. They have a dark brown to black skin and are rich in vitamin A and potassium. Apart from the Dioscorea opposita ( " Chinese yam " ) or Dioscorea japonica ( "Japanese mountain yams " or " Yamaimo " (山芋) ) affect all yam species eaten raw toxic. Yams are similar taste and appearance to sweet potatoes, but they are not related to them. In South America, Africa and the Caribbean yams is widespread, but in contrast to the sweet potato rarely acquire in Europe. Furthermore, it is an important starch supplier in the tropics. In China there is a project, using genetic engineering techniques to breed varieties of yam species that are optimized as energy crops for the production of fuel ethanol.
In natural medicine wild yam is used depending on the dosage for the relief of menopausal symptoms, PMS and against both of contraception as well as fertility problems. The use is controversial and requires an intensive study of the subject advance. The wild yam contains large quantities of diosgenin, a cholesterol derivative with additional hydroxyl groups in the side chain, attach the inner ether as more rings on the sterane skeleton. Although from diosgenin only by chemical degradation, the corpus luteum hormone progesterone can be obtained, diosgenin is called in esoteric literature and alternative medicine as a "natural " progesterone.
Species
The genus yams ( Dioscorea ) comprises about 350 to 800 species. Here is a selection:
- Dioscorea abyssinica
- Dioscorea alata ( purple yams, Syn: Dioscorea alata var purpurea ( Roxburgh ) A.Pouchet; D. purpurea Roxburgh. ) It forms quite different looking from root nodules.
- Dioscorea althaeoides
- Dioscorea amaranthoides
- Dioscorea aristolochiifolia
- Dioscorea auriculata
- Dioscorea altissima
- Dioscorea aspersa
- Balkan yams, or "Balkan Schmerwurz " ( Dioscorea balcanica )
- Dioscorea banzhuana
- Dioscorea bartlettii
- Dioscorea batata
- Dioscorea benthamii
- Dioscorea bicolor
- Dioscorea biformifolia
- Dioscorea biloba
- Dioscorea birmanica
- Dioscorea bulbifera
- Dioscorea campestris
- Dioscorea caucasica
- Yellow Guinea Yam ( Dioscorea cayenensis, Syn: Dioscorea occidentalis R.Knuth )
- Dioscorea chingii
- Dioscorea cirrhosa
- Dioscorea collettii
- Dioscorea composita
- Dioscorea cumingii
- Dioscorea convolvulacea ( Syn: Dioscorea convolvulacea subsp esaurientium ( Uline ) Uline ex R.Knuth, D. esurientium Uline, D. hirsuta M.Martens & Galeotti ).
- Dioscorea cotinifolia
- Dioscorea cyanisticta
- Dioscorea decipiens
- Dioscorea delavayi
- Dioscorea deltoidea
- Dioscorea demourae
- Dioscorea densiflora
- Dioscorea divaricata
- Dioscorea dodecaneura
- Dioscorea dregeana
- Dioscorea dumetorum ( bitter yam )
- Dioscorea elephantipes ( Syn: Tamus elephantipes L' Hér, Testudinaria elephantipes (L' Hér ) A.Dicks. .. )
- Potato yam ( Dioscorea esculenta, Syn: D. aculeata L., D. fasciculata Roxb, D. auct sativa, Oncus esculentus Lour. .. ) It forms rhizomes.
- Dioscorea Esquirolii
- Dioscorea exalata
- Florida yams ( Dioscorea floridana )
- Dioscorea floribunda
- Dioscorea fordii
- Dioscorea futschauensis
- Dioscorea galeottiana
- Dioscorea garrettii
- Dioscorea glabra
- Dioscorea glandulosa
- Dioscorea glomerulata
- Dioscorea gracillima
- Dioscorea grisebachii
- Dioscorea hassleriana
- Dioscorea hemicrypta
- Dioscorea hemsleyi
- Poisonous Yams ( Dioscorea hispida, Syn: Dioscorea Daemona Roxb. )
- Dioscorea hondurensis
- Dioscorea humifusa
- Dioscorea humilis
- Dioscorea japonica (syn.: Dioscorea belophylloides Prain & Burkill, D. kiangsiensis R.Knuth, D. pseudojaponica Hayata. ) It forms vertical root tubers.
- Dioscorea kamoonensis
- Dioscorea laxiflora
- Dioscorea linearicordata
- Dioscorea martini
- Dioscorea melanophyma
- Dioscorea menglaensis
- Dioscorea mexicana (syn.: Dioscorea macrostachya Benth. )
- Dioscorea monadelpha
- Dioscorea multispicata
- Dioscorea nelsonii
- Dioscorea nipponica
- Dioscorea nitens
- Dioscorea nummularia
- Dioscorea olfersiana
- Chinese yam, "Japanese mountain yam ", " Yamaimo ", " Korean yams " ( Dioscorea opposita, Syn: Dioscorea oppositifolia, Dioscorea batatas Decaisne, D. decaisneana Carrière, D. Doryphora Hance, D. Prain & Burkill potaninii, D. rosthornii Diels, D. swinhoei Rolfe. ) It forms vertical root tubers.
- Dioscorea ovata
- Dioscorea pallens
- Dioscorea panthaica
- Dioscorea pentaphylla
- Dioscorea persimilis
- Dioscorea pilcomayensis
- Dioscorea piperifolia
- Dioscorea poilanei
- Dioscorea polystachya
- Dioscorea polygonoides
- Dioscorea praehensilis
- Dioscorea preussii
- Dioscorea remota
- Dioscorea remotiflora
- Dioscorea retusa
- Guinea yam ( Dioscorea rotundata )
- Zanzibar yam ( Dioscorea sansibarensis )
- Dioscorea sagittata
- Dioscorea saxatilis
- Dioscorea sellowiana
- Dioscorea septemloba
- Dioscorea simulans
- Dioscorea sinuata
- Dioscorea sinoparviflora
- Dioscorea spiculiflora
- Dioscorea spongiosa
- Dioscorea subcalva
- Dioscorea subhastata
- Dioscorea subtomentosa
- Dioscorea sylvatica
- Dioscorea tentaculigera
- Dioscorea tenuipes
- Dioscorea tokoro
- Dioscorea transversa
- Indian yam ( Dioscorea trifida )
- Dioscorea valdiviensis
- Dioscorea velutipes
- Wild Yam ( Dioscorea villosa )
- Dioscorea wallichii
- Dioscorea xizangensis
- Dioscorea yunnanensis
- Dioscorea zingiberensis