1. Allen ON, Allen EK (1981) The Leguminosae, University of Wisconsin Press, Madison and MacMillan Publishers Ltd, London.
2. Atkins CA et al (1988) Plant Physiol. 86, 204–207.
3. Axelrod DI (1992) In Herendeen PS and Dilcher DI, eds, Advances in Legume Systematics: Part 4, the Fossil Record, pp 259–279. RBG, Kew.
4. Barrios E, Herrera R (1993) J. Trop. Ecol. In press.
5. Bergman B et al (1992) New Phytol. 122, 379–400.