''Cynanchum guehoi'', the Rodrigues cynanchum, is a rare plant from the subfamily Asclepiadoideae within in the family

Apocynaceae Apocynaceae (from ''Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison Members of the ...

. It is endemic to the island of

Rodrigues Rodrigues (french: Île Rodrigues, link=yes ; Creole: ) is a autonomous outer island of the Republic of Mauritius in the Indian Ocean, about east of Mauritius. It is part of the Mascarene Islands, which include Mauritius and Réunion. Rodr ...

in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

Description

Cynanchum viminale vs guehoi floral comparison - Ile aux Chats

''Cynanchum guehoi'' is a leafless

vine A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to such stems or runners themselv ...

with cylindrical, twining, fleshy, glabrous stems and a toxic white sap. When not in flower it is extremely easy to confuse with the common '' Cynanchum viminale'' which is widespread across Africa and southern Asia and also naturally occurs in Rodrigues. The fragrant flowers smell faintly of Jasmine. They are born in bunches, at the branch internodes. Each flower has five outer lobes, which open out and look like the petals of a flower. However the Rodrigues cynanchum's inner lobes are formed into a single corona in the centre, about 1.5 mm high. The tip of each inner lobe is triangular, with a thick, slightly curved lip. The related '' Cynanchum viminale'' also has five outer lobes resembling petals. However the corona is skirted at its base by a thin ring (the outer coronal ring). Its inner coronal lobes are smooth, oval and curved inwards like tusks.Strahm, W. ''Plant Red Data Book for Rodrigues'' Koeltz Scientific Books. 1989.

References

guehoi Endemic flora of Rodrigues {{Apocynaceae-stub