PATTERNS OF FLOWER AND INFLORESCENCE ARCHITECTURE IN CROCUS L. (IRIDACEAE)

Abstract

In Crocus, inflorescence characters are widely used for intrageneric systematics. Despite of this, spatial relations of flowers and involucral leaves are poorly documented. The focus of our study was the paracladial region and spatha leaves of C. flavus and C. vernus. The first indication of the lateral position of the flower in both species was zygomorphy of the androecium and gynoecium. In other Iridaceae (Freesia, Gladiolus) stamens also have unequal length. The homeotic substitution of stamens by petaloid organs makes zygomorphy in Freesia more distinct, thus we propose that flowers have a latent genetic program for zygomorphization. The second indication is the bidentate shape of bracts and bracteoles in C. flavus and tridentate structure of the basal involucre in C. vernus, which we interpret as a fusion of the foliage leaf and the prophyll of the inflorescence. The shape and the position of the lateral inflorescences (paracladia) were also investigated. In C. flavus, corms often born several paracladia in the axils of the green leaves, whereas in C. vernus we found a single paracladium in the axil of a scale inside the basal involucre. The correlation between the number of paracladia, their position and the spathe leaves were discovered. We propose to use these characters for the definition of two subgenera in Crocus.