*Botany Division, DSIR, Private Bag, Christchurch, New Zealand.
The adaptive significance of monoecism in Cnidoscolus urens (L.) Arthur (Euphorbiaceae)
Article first published online: 28 JUN 2008
Botanical Journal of the Linnean Society
Volume 85, Issue 4, pages 213–223, December 1982
How to Cite
BAWA, K. S., WEBB, C. J. and TUTTLE, A. F. (1982), The adaptive significance of monoecism in Cnidoscolus urens (L.) Arthur (Euphorbiaceae). Botanical Journal of the Linnean Society, 85: 213–223. doi: 10.1111/j.1095-8339.1982.tb00371.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Received December 1981, accepted for publication July 1982
- Butterfly pollination;
- Cnidoscolus urens;
- tropical deciduous forests
Cnidoscolus urens is a monoecious, selfcompatible herb. Male and female flowers differ structurally, but appear superficially similar and the principal dry season pollinator, a butterfly (Eurema daira) did not discriminate between them. Female flowers offered little or no nectar reward and may mimic males in order to receive pollen. Male flowers last only 1 day; female flowers usually last 1 day but may remain receptive for 7 days if unpollinated. Flowers opened between 00.00 hours and 01.00 hours, opening earlier as the wet season approached. This shift is probably correlated with a change to nocturnal moth pollination in the wet season.
Within an inflorescence there are c. 16 times more male than female flowers. Female flowers occur in the lowermost positions and open first. Female flowering is followed by a brief period when no flowers open and then by an extended period of male flowering.
Although there is no overlap between male and female phases within an inflorescence, nonsynchronous development of several inflorescences on one individual means that selfing is possible for nearly all female flowers. However, observations of pollinator behaviour indicate that butterflies frequently move to another plant after visiting one inflorescence. Thus there is a large degree of outcrossing in practice.