Flower Structure, Development, and Systematics in Passifloraceae and inAbatia(Flacourtiaceae)

Abstract

Flower morphology and development of nine species belonging to seven genera and two tribes of Passifloraceae and of Abatia americana (Flacourtiaceae) were studied. Floral structure supports a strong affinity of the two tribes Passifloreae and Paropsieae. Striking features in most species investigated are the solid styles and the distinctive multicellular papillae of the stigmatic surface. Development of the corona begins with a ring primordium. Further differentiation proceeds from the inner and outer edge toward the center of the primordium. This pattern does not support the hypothesis that the corona is of staminodial origin. The fleshy plate in the flower of Crossostemma laurifolium is formed by the androecium. It is not homologous to the nectary disk that is extrastaminal in Passifloraceae. The ancestral androecium of the Passifloraceae was either haplostemonous or one‐whorled polyandrous. The genus Adenia deviates in a number of characters from the rest of the Passifloraceae: (1) the styles are not solid; (2) the stigmas lack the characteristic papillae; and (3) the nectary is often composed of separate glands. Adenia may be a link between Passifloraceae and related families. Despite the presence of an extrastaminal corona in the genus, several other lines of evidence, including flower morphology and phytochemistry, indicate that Abatia is not a member of Passifloraceae. Rather, it should be included in the Flacourtiaceae.