Dischidia

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Dischidia
Dischidia collyris
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Gentianales
Family: Apocynaceae
Subfamily: Asclepiadoideae
Genus: Dischidia
Species

See text.

Dischidia is a genus of plants in the Milkweed family, Asclepiadaceae. It comprises about 80 known species which all grow as epiphytes and are native to tropical areas of China, India and most areas of Indo-China. Dischidia are closely aligned with the sister genus Hoya. Unlike Hoya, the genus Dischidia, is poorly known and has not been studied as closely.

Most Dischidia grow in arboreal ant nests of different species and some have developed a symbiotic relationship where the plant has developed modified leaves to either provide housing or storage. Of these there are two types of modification to the leaves. Three species develop bullate leaves which are hollow root-filled structures. These are Dischidia complex Griff, Dischidia major (Vahl) Merr. and Dischidia vidalii Becc. Both produce normal leaves (cordate in shape) in addition to the bullate leaves. These bullate leaves are formed when the outer margins of a leaf stop growing while the center of the leaf continues to grow. As time progresses the leaf margins curl under to close the gap which creates a small hole.

A number of species develop imbricate leaves which hold tightly to the growing surface. The underside of the leaf has a space which is filled with roots that the ants take advantage of. Examples of these species are Dischidia astephana Scort. ex King & Gamble, Dichidia imbricata (BL)Steud. and Dischidia platyphylla Schlecther, but there are many more. Plants with this type of growth habit are sometimes called Shingle Plants, which are given this name because the leaves tend to overlap as the grow up or down the surface and give the appearance of shingles on a roof.

Of the 80 species in the genus, there are few in widespread cultivation. The species list below is a preliminary list of species that have been named in some source but may not be validly published. Therefore it should be viewed as a working list.

Species list[edit]

D. major illustration from Pflanzenleben by Anton Kerner von Marilaun, 1913
D. bengalensis, Göttingen
D. imbricata on Millettia pinnata at Foster Botanical Garden, Honolulu
D. nummularia habitus, Berlin

References[edit]