Notes on the floral biology and pollination syndrome of Echinopsis chiloensis (Colla) Friedrich & G.D.Rowley (Cactaceae) in a population of semiarid Chile

we report some aspects of the floral biology ofechinopsis chiloensis ssp. chiloensis in a population near to the northern limit of its distribution. anthesis is strictly diurnal and flowers remain open during 492 min on the average. echinopsis chiloensis is self-incompatible. flower longevity, nectar production along day, and floral visitors indicate that this population fits well to a diurnal insect pollination syndrome. these results contrast with a previous report indicating nocturnal anthesis and mixed mellitophylous-sphingophylous pollination syndrome in populations near to the southern limit of the distribution range. we suggest that the pollination syndrome of e. chiloensis is a labile rather than fixed condition that may depend on the abiotic characteristics and geographical location of the population under assessment.