AN UPDATED INTERPRETATION OF THE ANDROECIUM OF THE FUMARIACEAE

A study of the floral development of Dicentra formosa, Corydalis lutea, and Hypecoum procumbens was carried out to better understand the nature of the androecium in Fumariaceae. Sepals emerge successively in a median position and are followed by two alternating pairs of petals. Four stamen primordia are formed in a diagonal position. They are promptly followed by two lateral, slightly externally inserted primordia. In Dicentra and Corydalis the stamens arise on two crescent-shaped protuberances. In Hypecoum, four diagonal androecial primordia fuse into two median staminal complexes. The gynoecium emerges as a girdling primordium with four growth centers. Different interpretations of the androecium are discussed. It is demonstrated that the androecium in the Fumariaceae consists basically of two whorls: an outer whorl of four alternipetalous stamens and an inner whorl of two lateral stamens superposed to the outer petals. The monothecal nature of the alternipetalous stamens and the fusion of the stamens in two triplets is probably caused by a spatial median compression of the flower bud. The androecium of Hypecoum is the result of interprimordial growth between the pairs of monothecal stamens, and the androecium of Pteridophyllum arises through the loss of the two lateral stamens superposed to the outer petals.