The Calix Tube and Floral Nectar Tissue in Passiflora L.: What Can they Tell us about the Flower Structure Evolution?

Reproduction in Passifloraceae Juss. ex Roussel can involve self-compatible and self-incompatible systems, where the participation of biotic pollinators is necessary. The behavior of pollinators can be influenced by chemical and morphological characteristics of flowers, and among the kind rewards offered to pollinators is nectar. This study analyzed the anatomy of the calyx tube and floral nectar of t species of Passiflora L., as it relates to different pollination syndromes. For anatomical studies, analyzes were performed using optical microscopy. The anatomy and morphology of the calyx tube demonstrated that plants with the same pollination syndrome possess similar anatomical and morphological characteristics, and these attributes may are adapted to the biotic pollinators. The ornithophily and chiropterophily probably evolved from melittophylous flowers in passionflowers, being more diversified in the subgenus Passiflora. Histological analysis identified the location of secretory tissue, such as the exudation of nectar by stomata, papillae or by the epidermis itself. A reproducao em Passifloraceae Juss. O ex Roussel envolve sistemas auto-compativeis ou auto-incompativeis, onde a participacao de polinizadores bioticos e necessaria. O comportamento dos polinizadores pode ser influenciado pelas caracteristicas quimicas e morfologicas das flores, e entre as recompensas oferecidas esta o nectar. O objetivo deste estudo foi analisar a anatomia do tubo de calice e nectar floral de especies de Passiflora L., com diferentes sindromes de polinizacao. Para os estudos anatomicos foi realizado analise em microscopia otica. A anatomia e morfologia do tubo calice demonstraram que plantas com a mesma sindrome de polinizacao possuem caracteristicas anatomicas e morfologicas semelhantes, atributos que podem ser adaptados aos polinizadores bioticos. Provavelmente a ornitofilia e quiropterofilia evoluiram de flores melitofilas, sendo mais diversificadas no subgenero Passiflora. A analise histologica identificou a localizacao do tecido secretor, com exsudacao do nectar pelos estomatos, papilas ou pela propria epiderme.