Rhizanthes
Content
Description
Flowers unisexual or bisexual, buds pyriform, from a basal cupule attached to or arising from the roots or basal stem and aerial roots of the host, surrounded by three or four whorls of 5 scales, these sessile, imbricate, concave, more or less ovate, entire, brownish.
Fruits hidden under dried-out flowers.
Seeds with the same structure as those of Rafflesia .
Distribution
Asia-Tropical: Borneo present; Jawa (Jawa present); Malaya (Peninsular Malaysia present); Sumatera (Sumatera present)
In Malesia 2 species (Sumatra, Peninsular Malaysia, Java, Borneo).
Ecology
The host of both species is in general Tetrastigma papillosum (Blume) Planch., sometimes also T leucostaphylum (Dennst.) Alston ex Mabb. .
Notes
A very clever field investigation into the pollination of Rhizanthes (most likely R. lowii) in S Thailand and the Malay Peninsula (Perak) was reported by Bänziger (1996). He observed 900 visits of Calliphoridae (Bow flies) to 270 flowers and considers 6 species to be pollinators and the others non-pollinating visitors. His conclusion is that Rhizanthes just like Rafflesia mimics carrion in a pollination syndrome based on brood-site deception. Apparently eggs can be laid but the larvae starve to death. Insects are also lured to the nectaria at the base of the bayonets. As known to all observers, the flowers of Rhizanthes smell to the human nose much fainter than those of Rafflesia. See for other interesting details the original publication.