Australian Tropical Rainforest Plants - Online edition

Cynanchum viminale subsp. brunonianum (Wight & Arn.) Meve & Liede

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Flowers. © CSIRO
Scale bar 1mm. © CSIRO
Vine stem bark and vine stem transverse section. © CSIRO

Meve, U. & Liede-Schumann, S. (2012) Kew Bulletin 67: 754.

Common name

Caustic Bush; Vine, Caustic; Pencil, Caustic,; Caustic Pencil; Milkbush; Caustic Vine


Usually grows as a shrub-like plant but can also assume the architecture of a vine with a stem perhaps attaining 3-4 cm diam.


Leaves reduced to small, triangular scales about 1-1.5 mm long. Photosynthetic material present in the green succulent branches which produce copious amounts of milky exudate when cut or broken.


Inflorescence a short raceme or fascicle. Pedicels about 7-8 mm long. Flowers about 9-15 mm diam. Calyx lobes triangular, about 0.8-1 mm long. Corolla lobes about 5-6 x 2 mm, recurved. Staminal corona about 3-4 mm diam. Anthers about 1 mm long, appendages terminal. Carpels about 0.8-1 mm long. Styles free at the base, about 1.2 mm long. Style head about 0.8-1 mm.


Follicles about 7-9 x 0.4 cm. Seeds about 5-6 x 1.5-2 mm, plumes about 15-17 mm long.


Features not available.

Distribution and Ecology

Occurs in WA, NT, CYP, NEQ, CEQ and southwards into New South Wales. Altitudinal range in northern Australia from near sea level to 550 m. Grows in rocky areas in open forest, vine thicket and monsoon forest. Also occurs in Africa, Asia and Malesia.

Natural History & Notes

A food plant for the larval stages of the Australian Crow Butterfly. Common & Waterhouse (1981).

Sarcostemma brunonianum Wight & Arn., Contr. Bot. India 59 : (1834), Type: Herb. Wight, propr. 1557 Sarcostemma bunoniana W & A. Peninsula Ind. orientalis 1836; iso: G-DC.  Sarcostemma viminale subsp. brunonianum (Wight & Arn.) P.I.Forst.Australian Systematic Botany 5(1): 63 (1992).
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