Floral Ecology, Carinal-Lobe Release, Pollination and Reproductive Success in the Wild and Domesticated Forms of Hyptis suaveolens (L.) Poit. (Lamiaceae) in Mexico



AbstractHyptis suaveolens is a weedy species growing wild in the tropics. In Mexico, additionally, it has two non-weedy domesticated forms. The wild form is designated as violeta and the domesticated ones as blanca-violeta and blanca, based on stem, flower and seed characters. The wild form has flowers with violent carinal explosion, while the domesticated forms have flowers with non-violent carinal explosion. The carinal structure is formed by the median lobe of the lower corolla lip which conceals the stamens and the stigma even after the unfolding of the other lobes of the corolla. The carinal lobe explodes when the flower visitor lands on the flower. All three forms are foraged indiscriminately by the same species of bees. Flies and a wasp also forage on these flowers, but their role in pollination is negligible. The foraging behaviour of bees suggests that selfing is promoted during forenoon hours and outcrossing during afternoon hours. There is a direct relation between flower density, bee frequency and reproductive success. Bees approach the flowers from the front probe in an upright position; and they effect carinal-tripping and sternotriby while probing for either pollen, nectar, or both. Apis and Exomalopsis probe the flowers also from above the upper corolla lip in which case pollination is not ordinarily effected. All three forms are both self- and cross-pollinating. The domesticated forms have higher fecundity than the wild. The wild form reseeds itself, while the domesticated ones cannot, as their larger fruiting calyx requires seed-dispersal agents. H. suaveolens, particularly its domesticated forms, can be best exploited as a potential new crop.