Dioscorea
Encyclopedia
Dioscorea is a genus of over 600 species of flowering plant
s in the family Dioscoreaceae
, native throughout the tropical and warm temperate
regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates. It is named after the ancient Greek
physician and botanist Dioscorides.
They are tuber
ous herbaceous
perennial
liana
s, growing to 2–12 m or more tall. The leaves
are spirally arranged, mostly broad heart-shaped. The flower
s are individually inconspicuous, greenish-yellow, with six petals; they are mostly dioecious
, with separate male and female plants, though a few species are monoecious
, with male and female flowers on the same plant. The fruit
is a capsule
in most species, a soft berry
in a few species.
Several species, known as yams
, are important agricultural
crops in tropical regions, grown for their large tubers. Many of these are toxic when fresh, but can be detoxified and eaten, and are particularly important in parts of Africa
, Asia
, and Oceania
(see yam
article).
The closely related genus Tamus
is included in Dioscorea by some sources, but is maintained as distinct by others. For Dioscorea communis (L.) Caddick & Wilkin, see Tamus communis.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the family Dioscoreaceae
Dioscoreaceae
Dioscoreaceae is a family of monocotyledonous flowering plants, with about 750 species in eight or nine genera. The best-known member of the family is the Yam ....
, native throughout the tropical and warm temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates. It is named after the ancient Greek
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...
physician and botanist Dioscorides.
They are tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
ous herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
liana
Liana
A liana is any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy to get access to well-lit areas of the forest. Lianas are especially characteristic of tropical moist deciduous...
s, growing to 2–12 m or more tall. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are spirally arranged, mostly broad heart-shaped. The flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are individually inconspicuous, greenish-yellow, with six petals; they are mostly dioecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with separate male and female plants, though a few species are monoecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with male and female flowers on the same plant. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a capsule
Capsule (fruit)
In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels that in most cases is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example...
in most species, a soft berry
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
in a few species.
Several species, known as yams
Yam (vegetable)
Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...
, are important agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
crops in tropical regions, grown for their large tubers. Many of these are toxic when fresh, but can be detoxified and eaten, and are particularly important in parts of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and Oceania
Oceania
Oceania is a region centered on the islands of the tropical Pacific Ocean. Conceptions of what constitutes Oceania range from the coral atolls and volcanic islands of the South Pacific to the entire insular region between Asia and the Americas, including Australasia and the Malay Archipelago...
(see yam
Yam (vegetable)
Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...
article).
Selected species
|
Dioscorea mexicana Mexican yam or barbasco de placa is a species of yam in the genus Dioscorea. It ranges from the state of Veracruz in Mexico south to Panama. It is notable for its production of diosgenin, which is a precursor for the synthesis of hormones such as progesterone. Russell Marker developed the... Dioscorea opposita Dioscorea opposita is a type of yam that may be eaten raw.... - Shan yao in Chinese Dioscorea orangeana Dioscorea orangeana, is a tuberous vining flowering plant in the genus Dioscorea, endemic the Forêt d’Orangea near Antsiranana in Madagascar. The tuber is possibly edible, and unlike most other Dioscorea species, the tuber has many finger-like lobes as opposed to a single tuber... Wilkin Dioscorea rotundata Dioscorea rotundata, the "white yam", is a species of yam native to Africa. It is one of the most important cultivated yams, along with the Dioscorea cayenensis. It is sometimes known as the "Guinea Yam" D... Dioscorea transversa Dioscorea transversa, Pencil yam, is a vine of eastern and northern Australia.The leaves are heart-shaped, shiny, with 5-7 prominent veins. The seed pods are rounded, green or pink before drying to a straw brown papery texture. The edible tubers are typically slender and long... Dioscorea trifida The climbing perennial vine Dioscorea trifida is a species of yam native to the Caribbean and tropical Central and South America. It is known by a variety of common names, including Indian yam, napi, yampie or yampi, name mapuey, aja, cara doce, and cushcush... |
The closely related genus Tamus
Tamus
Tamus is a genus of one or two species of flowering plants in the family Dioscoreaceae, native to Europe, northwestern Africa, and western Asia. The genus is now often included within the related genus Dioscorea, but is maintained as distinct by some authors.Species*Tamus communis L. -References:***...
is included in Dioscorea by some sources, but is maintained as distinct by others. For Dioscorea communis (L.) Caddick & Wilkin, see Tamus communis.