Functional significance of the androecium in staminate and hermaphroditic flowers of Solanum carolinense (Solanaceae)

Abstract.

The role of the androecium differs in male and hermaphroditic flowers of the andromonoecious Solanum carolinense. Although the anthers in male, and in the much more abundant hermaphroditic flowers, are the same size and they bear the same quantity of pollen, these organs exhibit some specialization in the two flower types. Experimental results imply that significant roles of the male organs in hermaphroditic flowers are as sources of pollinator reward (pollen) in these nectarless flowers, at least as near-distance attractive elements, and as landing platforms. Evidence for the latter comes from experiments that showed bees visited flowers (alighted) that lack stamens with a much lower frequency. In contrast, the stamens of the male flowers function primarily as possible near-distance attractors and as a source of pollen for reproduction. Male flowers are seldom open concurrently with the hermaphroditic flowers on the same plant and thus the staminate flowers function primarily as pollen donors because they cannot often serve as attractants to hermaphroditic flowers.