Floral and reproductive biology of Commelina erecta L. (Commelinaceae) in a coastal dune system on the Gulf of Mexico*

The most common sexual systems found in Commelinaceae species are hermaphroditic and andromonoecious, and although enantiostyly is also recognized in the family, it has only been recorded in a few species. The presence of different sexual systems (v.gr., andromonoecious and enantiostyly) in the same species is still unnoted. Commelina erecta is a common andromonoecious-enantiostylous species (i.e., it bears male, left-styled and right-styled flowers) of the coastal dunes of La Mancha in Veracruz, Mexico. Our aims were to determine: (1) the type of enantiostyly, (2) the floral morph-ratios in a population, (3) the differences in size of flowers structures among floral morphs, to (4) characterize the floral visitor community in the different floral morphs, and (5) evaluate differences in fruit set in the hermaphroditic flowers. We found that C. erecta in La Mancha is characterized by non-reciprocal monomorphic enantiostyly. The proportion of floral morphs varied among sampling months. Discriminant analysis and a Wilcoxon test using canonical scores indicated that the anther area and filament length of male flowers are larger in size than those in hermaphroditic flowers. In total, we recorded 220 visits to the flowers of C. erecta by 18 species of insects belonging to five orders. Our study shows that the main floral visitor was the halictid bee Augoclorella sp. Left- and right-styled flowers were equally successful in terms of producing fruits and seeds of the same weight and size, but overall reproductive success was low, with fruit set of only 29%.

Automated summary

The study found that in La Mancha in Veracruz, Mexico, Commelina erecta exhibits non-reciprocal monomorphic enantiostyly. The proportion of floral morphs varied among different sampling months. Male flowers had larger anther area and filament length compared to hermaphroditic flowers. A total of 220 visits to the flowers were recorded, with the main floral visitor being the halictid bee Augoclorella sp. Both left- and right-styled flowers had equal success in producing fruits and seeds of the same weight and size, but the overall reproductive success was low, with a fruit set of only 29%.