This study investigated pollination mechanisms and breeding systems in five Commelina variants: two subspecies of Commelina diffusa (C. diffusa subsp. aquatica and C. diffusa subsp. montana, each having two staminodes); two variants of C. erecta (with three staminodes); and C. lagosensis (also with three staminodes). In all three species, the staminodes have six lobes but only two fertile lateral lobes. We collected field samples and cultivated new plants from stem cuttings. When the plants flowered, we evaluated floral morphology, floral biology and breeding systems, creating eight separate experimental treatments, involving spontaneous and hand pollination, as well as varying degrees of emasculation of the flowers. Although the pollen from the lateral and central anthers was capable of siring seeds, the staminode pollen rarely set seeds. Commelina diffusa subsp. aquatica presented very low percent pollen stainability in all three of its stamens and produced no seeds in any of the pollination treatments. In all three species, the stigma was often directed toward the central anther during coiling of the style. Our results show that C. diffusa subsp. aquatica is sterile and that, in the other Commelina variants studied, pollination occurs mainly through autogamy via the lateral and central anthers.
Commelina; pollen viability; stamen type; autogamy
