Silene vulgaris occurs in Israel as a stolonifcrous tetraploid which forms mostly sexually polymorphic populations. Fully hermaphrodite and fully male‐sterile plants are linked by a range of intermediate forms which are gynomonoecious and bear hermaphrodite, male‐sterile, and partially male‐sterile flowers. Male‐sterile flowers differ from hermaphrodite ones by having a narrower calyx, a shorter corolla, a thicker style, and a considerably larger stigmatic area with longer papillae which are more markedly bulbous basally. In individual anthers of hermaphrodite flowers, diameters of stained pollen grains showed a continuous variation from 36 to 80 μm with a modal value of 56. About 30% of pollen was found to be non‐stainable. Reduction in male fertility occurs at different levels, from small or inviable pollen grains through abortion of single anthers, abortion of entire androecia, and through different degrees of gynomonoecy to totally male‐sterile individuals. The proportion of stainable pollen to ovules in hermaphrodite flowers alone was found to be less than 100. From the data presented, less than a third of all ovules produced in the different kinds of flower develop into seeds. This may reflect an inadequacy of pollen, which the local population of S. vulgaris can tolerate because of its stoloniferous habit.
Ultraviolet reflectance properties of flowers in 26 East Mediterranean wild species and three cultivated species of the Cruciferae are surveyed. These properties were disclosed by photography of fresh or herbarium specimens through a visible‐light absorbin filter. The so‐revealed spectral polymorphism is related to the previously known visible flower colors. Ultraviolet floral patterns which act as nectar guides to pollinators are described. Hitherto unreported patterns were found to result from ultraviolet absorption by sepals, ultraviolet reflection from anther tips, and, in one case, ultraviolet absorption by a peripheral part of the corolla. In some cases patterns differ between closely related taxa and could therefore be of diagnostic value.
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