''Calotropis'' is a
genus of
flowering plants in the family
Apocynaceae, first described as a genus in 1810. It is native to southern Asia and North Africa.
They are commonly known as milkweeds because of the
latex they produce. ''Calotropis'' species are considered common
weeds in some parts of the world. The flowers are fragrant and are often used in making floral tassels in some mainland
Southeast Asian cultures. Fibers of these plants are called madar or mader. ''Calotropis'' species are usually found in abandoned farmland.
Botanical description
''Calotropis gigantea'' and ''C. procera'' are the two most common species in the genus. ''Calotropis gigantea'' grows to a height of while ''C. procera'' grows to about . The leaves are sessile and sub-sessile, opposite, ovate, cordate at the base. The flowers are about in size, with umbellate lateral cymes and are colored white to pink and are fragrant in case of ''C. procera'' while the flowers of ''C. gigantea'' are without any fragrance and are white to purple colored, but in rarer cases are also light green-yellow or white. The seeds are compressed, broadly ovoid, with a tufted micropylar coma of long silky hair.
Pollination is performed by bees (
entomophily) by the following mechanism:
The
stigmas and
androecia
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
are fused to form a
gynostegium. The
pollen
Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
are enclosed in
pollinia (a coherent mass of pollen grains). The
pollinia are attached to an adhesive glandular disc at the stigmatic angle. When a bee lands on one of these, the disc adheres to its legs, and the pollinium is detached from the flower when the bee flies away. When the bee visits another flower, the flower is pollinated by the adhering pollinium on the bee.
;Species
[The Plant List, genus ''Calotropis'']
/ref>
# '' Calotropis acia'' Buch.-Ham. - India
# '' Calotropis gigantea'' (L.) Dryand. - China, Indian Subcontinent, Southeast Asia
# '' Calotropis procera'' (Aiton) Dryand. - China, Indian Subcontinent, Southeast Asia, Middle East, North Africa
;formerly included[
''Calotropis sussuela'', synonym of '' Hoya imperialis''
]
Toxicity
The milky exudation from the plant is a corrosive poison. ''Calotropis'' species are poisonous plants; calotropin, a compound in the latex, is more toxic than strychnine
Strychnine (, , US chiefly ) is a highly toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, or absorbed through the eye ...
. Calotropin is similar in structure to two cardiac glycosides which are responsible for the cytotoxicity of '' Apocynum cannabinum''. Extracts from the flowers of ''Calotropis procera'' have shown strong cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
activity. The extracts are also harmful to the eyes.
Cattle often stay away from the plants because of their unpleasant taste and their content of cardiac glycosides.
Cultural significance
The flowers of the plant are offered to the Hindu deities Shiva, Ganesha, Shani Dev and Hanuman.
Gallery
File:ThoraThora1.JPG, '' Calotropis procera''
File:Starr_010503-9002_Calotropis_procera.jpg, ''Calotropis procera'' branch with flowers
File:Starr 010701-9001 Calotropis procera.jpg, ''Calotropis procera'' fruit
File:Calotropis procera.jpg, ''Calotropis procera''
File:Adrar-Calotropis procera (1).JPG, ''Calotropis procera''
File:Algodon de seda (Calotropis procera) 3.jpg, ''Calotropis procera''
File:Calotropis giganteaRHu3.JPG, '' Calotropis gigantea''
File:C. gigantea.JPG, ''Calotropis gigantea''
File:Starr 070730-7945 Calotropis gigantea.jpg, Floral tassels made from ''Calotropis'' flowers.
References
External links
USDA classification for ''Calotropis''
''Calotropis procera''
{{Taxonbar, from=Q310216
Asclepiadoideae
Apocynaceae genera
Taxa named by Robert Brown (botanist, born 1773)
Poisonous plants