Biología reproductiva de amasonia campestris (AUBL.) Moldenke (Verbenaceae) en Los LLanos Centrales de Venezuela

reproductive biology of amasonia campestris was studied in the venezuelan central llanos. the flowers open between 3:30 and 7:00 h, and last for two days. the flowers are protandrous and the number of opened flowers per inflorescence varies between 1 and 5 ( = 2.2, sd = 2.3). the nectar is produced and accumulated in a basal cavity of the corolla. nectar secretion begins at 7:00 and finishes at 13:00 h. the total nectar volume produced per flower during two days of longevity was between 8.55 and 35.15 μl/flower (= 21.75 μl, sd = 9.19). the flowers were visited by four butterfly (pieridae) and three hummingbird species. the highest activity of hummingbirds was during the morning and afternoon, and the highest activity of butterflies occurred during the midday at low and high plant density, however, the visits were higher for hummingbirds and butterflies at high plant density. the patterns of nectar secretion were positively correlated with the number of visits of two hummingbirds, amazilia fimbriata obscuricauda (n = 8, r = 0.95, p< 0.0001) and chlorostilbon mellisuga caribaeus (n = 8, r = 0.73, p < 0.02) at high plant density. fruit and seed set in cross-pollinated flowers were higher than hand self-pollination and spontaneous self-pollination respectively, which suggest self-incompatibility. more than 50% of floral biomass is allocated to the corolla. reproductive/vegetative biomass ratio was 0.37, which indicate an unbalanced between sporophyll and perianth. pollen/ovule ratio was 1250. natural fruit set was 64.26% and seed set (relative to ovules) was 73.94%. high value of relative fecundity in a. campestris seems to be mainly determined by the combination of four traits: pollination efficiency, low number of ovules per flower, protandry, and perennial herbaceous life form.