Fig. 1.

Sexual dimorphism in S. latifolia. Shown are flower meristems observed by scanning electron microscopy. Developmental stages are as defined by Farbos et al. (7). At stage 3, two types of primordia are visible: sepal and stamen (petal primordia are initiated later and are not yet visible). The center of the flower meristem has not yet initiated carpel primordia. No difference is observed between flower meristem from male or female plant. At stage 5, all of the primordia are initiated. In flower meristem from female plants, carpel primordia appear as a wide dome. In flower meristem from male plants, the central dome is five times smaller than in the females and corresponds to the filament primordia. At stage 8, the difference between males and females is very clear. The five fused carpels in the center of the female flower are well developed, whereas the center of the male flower exhibits an undifferentiated filament. se, sepal primordia; st, stamen primordia; fmc, flower meristem center; ca, carpel primordia; f, filament primordia; sta, stamen; fi, filament; car, carpel.