Diurnal versus nocturnal pollination of Brunsvigia gregaria R.A. Dyer (Amaryllidaceae) at a coastal site

Members of the amaryllid genus Brunsvigia appear to show considerable variation in pollination syndromes, but experimental studies have been limited to two species, one pollinated by sunbirds and one by moths. Here we present the results of a simple exclusion experiment designed to shed light on the pollinators of the narrowly distributed species B. gregaria. Experimental flowers were left unbagged, or were bagged during night-time only, day-time only, or both day-time and night-time. Treatments started when flowers first matured and continued until senescence, after which we counted the number of fertile seeds per capsule. Flowers in treatment groups left open during the daytime produced significantly more seeds than flowers bagged during the daytime, whereas nocturnal bagging made little difference to seed number, indicating near-complete dependence on diurnal pollinators. Based on anecdotal observations we speculate that sunbirds - specifically Nectarinia famosa and possibly Cinnyris afer - are the most likely pollinators of B. gregaria.