The family includes three genera with around 600 to 870 species . Their types are mainly found in warm to tropical climates. In Central Europe, there is only one type of yam plant native, the Schmerwurz ( Dioscorea communis ). Some species are starch-producing food crops and the ingredients of some species are known for their medicinal properties .
Habit and leaves
The leaves are seldom opposite, mostly alternate and arranged helically on the stem axis . The leaves are often divided into a petiole and a leaf blade. This is only seldom the case with monocot plants , but is found e.g. B. also with the jacks . Extra-floral nectaries are often found on the leaves, which are often large . The leaf blades are simple or compound; the leaf veins are arched and palmatized and the leaf margin is smooth.
Inflorescences and flowers
The mostly unisexual, in Stenomeris hermaphroditic flowers are threefold and radial symmetry . The bracts are designed the same and have six tepals . Nectaries are present in the flowers. In the male flowers there are usually two circles with three stamens each. Either all of the stamens are fertile or those of a circle are converted to staminodes. The three pistils have become an under constant (syncarp) ovary grown.
The flower formula is:
Ingredients and usage
Yams contain flavonols and calcium oxalate . In parts of the yam family, steroid saponins (e.g. diosgenin ) can often be found; they can be used as a starting material for the semi-synthetic production of some hormones .
Many species are grown as useful plants in the tropics ( yams ). For example, Dioscorea batatas is planted in East Asia . Their underground tubers are edible and an important source of starch in the tropics .
Some species ( Dioscorea elephantipes (L'Hér.) Engl. , Dioscorea mexicana Scheidw. , Dioscorea sylvatica Eckl. , Dioscorea macrostachya Bentham (Syn .: Testudinaria macrostachya (Bentham) Rowley )) are used as "succulent" ornamental plants ; however, they are not succulent, but have interestingly shaped tubers.
The family name was first published in 1810 by Robert Brown in Prodromus Florae Novae Hollandiae , 294. The type genus is Dioscorea L. For a long time, only the species that are now included in the genus Dioscorea belonged to this family; the species of some former genera have been incorporated into the Dioscorea since 2000 . Some authors also include the species of the genus Tacca , which can represent a separate family Taccaceae , here. The genera of the previously independent families Avetraceae Takht. , Stenomeridaceae J.Agardh , Tamaceae Bercht. & J. Presl , Tamnaceae J. Kickx f. and Trichopodaceae Hutch. are now part of the Dioscoreaceae R.Br. assigned.
Here are the three genera of the yams (without Tacca ):
- Yam ( Dioscorea L. , Syn. : Borderea Miègev. , Botryosicyos Hochst. , Elephantodon Salisb. , Epipetrum Phil. , Hamatris Salisb. , Helmia Kunth , Higinbothamia Uline , Hyperocarpa (Uline) GMBarroso , Merione Salisb. , Nanarepenta Matuda , Oncorhiza Pers . , Oncus Lour. , polynomials Salisb. , Rajania L. , Rhizemys Raf. , Ricophora Mill. , Sismondaea Delponte , Strophis Salisb. , tamus L. , Tamnus Mill. , Testudinaria Salisb. ex Burch. , Ubium J.F.Gmel. ): It is pantropically distributed with around 600 (350 to 800) species today.
- Stenomeris planch . (Syn .: Halloschulzia Kuntze ): The only two types are common in western and central Malesia :
- Trichopus Gaertn. (Syn .: Avetra H.Perrier ): It contains two types:
Dioscorea balcanica , fruiting plant
Fruits and leaves of the common groundwort ( Dioscorea communis )
Flower of Trichopus zeylanicus
- The Dioscoreaceae family on the AP website. (Sections systematics and description)
- The families of the Dioscoreaceae and the Trichopodaceae at DELTA by L. Watson & MJ Dallwitz. (Section description)
- Lauren Raz: Dioscoreaceae. , P. 479 - same text online as printed work , In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico. Volume 26: Magnoliophyta: Liliidae: Liliales and Orchidales , Oxford University Press, New York and Oxford, 2002. ISBN 0-19-515208-5
- Chih-chi Ting, Michael G. Gilbert: Dioscoreaceae,, p. 276 - online with the same text as the printed work , Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China. Volume 24: Flagellariaceae through Marantaceae , Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 2000. ISBN 0-915279-83-5
- Lizabeth R. Caddick et al .: Yams and their allies: Systematics of Dioscoreales. In: KL Wilson, DA Morrison (Eds.): Monocots: Systematics and Evolution. , Melbourne, 2000, pp. 475-487.
- Lizabeth R. Caddick, Paul Wilkin, Paula J. Rudall, Terry AJ Hedderson, Mark W. Chase: Yams reclassified: a recircumscription of Dioscoreaceae and Dioscoreales. In: Taxon , Volume 51, Issue 1, 2002, pp. 103-114.
- Entry in the Western Australian flora .
- H. Huber : Dioscoreaceae . In: K. Kubitzki, H. Huber, PJ Rudall, PS Stevens, T. Stützel: The families and genera of vascular plants. Vol.3 . Springer-Verlag, Berlin, Germany 1998, ISBN 3-540-64060-6 (accessed January 14, 2014). Pp. 216-235
- H. Huber : Trichopodaceae . In: K. Kubitzki, H. Huber, PJ Rudall, PS Stevens, T. Stützel: The families and genera of vascular plants. Vol.3 . Springer-Verlag, Berlin, Germany 1998, ISBN 3-540-64060-6 (accessed January 14, 2014). Pp. 441-443
- Rafaël Govaerts (Ed.): Dioscoreaceae. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved June 24, 2018.