Secretory Trichomes, a Substitutive Floral Nectar Source in Lundia A. DC. (Bignoniaceae), a Genus Lacking a Functional Disc

This is the first report of corolla-borne secretory trichomes that substitute in role for a non-functional disc in a species of the neotropical genus Lundia A. DC. (Bignoniaceae). The floral biology and flowering phenology of Lundia cordata were investigated at two remnants of tropical rainforest in northeastern Brazil. This species is a typically omithophilous liana, with reddish, tubular, scentless flowers. The flowers are resupinate, protandrous and last for 2 d. There is a vestigial non-functional perigynous disc and nectar is secreted by glandular trichomes distributed along the internal surface of the corolla. The nectar is stored at the base of the corolla tube, thus showing secondary nectar presentation. The nectariferous trichomes are multi-cellular, uniseriate, with a basal foot cell rooting in the epidermis, one neck cell, and a glandular head with 13 cells on average. Three species of hummingbirds (Amazilia fimbriata, Eupetomena macroura and Phaethornis pretrei) serve as pollinators. Phaethornis ruber, Xylocopa bees, wasps and diurnal moths are considered nectar thieves.