The reproductive biology encompassing phenology, ¯oral biology, pollination and breeding systems, of Butea monosperma, a beautiful tree of the Indian subcontinent, was investigated in a protected dry, deciduous forest located in New Delhi. Phenological studies indicated that although the species shows a regular ¯owering season, all trees do not ¯ower every year. Flowers are typically papilionaceous; the stigma is wet papillate and the style is hollow. The ¯owers show characteristics of bird pollination being large and bright orange-red in colour with copious amounts of nectar, and exhibiting diurnal anthesis. Although the ¯owers are frequented by as many as seven species of birds belonging to six families, only one species, the purple sunbird (Nectarinia asiatica), is the effective pollinator. The ¯owers are also pollinated by the three-striped squirrel (Funambulus tristiatus). Unlike other ¯ower visitors, these two pollinators forage the nectar from the open side of the keel (legitimate path) during which pollen grains are deposited on their body parts. After the ®rst visit of a sunbird or a squirrel, virgin ¯owers showed pollen load on the stigma and developed into fruits. B. monosperma shows a weak form of selfincompatibility. Fruit set following manual self-pollination (5´25 %) was comparable with open-pollination (approx. 5 %) but was signi®cantly lower than manual cross-pollination (22´51 %). This indicates that there is a high degree of geitonogamous pollination in this species, which may lead to a weakening of self-incompatibility as a means of reproductive assurance. The results are analysed in the light of prevailing discussions on specializedvs. generalized pollination systems.