Flowers of the neotropical genus Cochliostema are the largest and among the most complex and fragrant in Commelinaceae. Cochliostema is further characterized by its peculiar androecium consisting of three fertile stamens and three antherless staminodes. The fertile stamens are on one side of the flower and united by their filaments, forming a compound structure that curves to the flower's right as the flower opens. The anthers are longitudinally dehiscent, spirally coiled, and enveloped by petaloid extensions of the filaments of the two lateral stamens contributing to the three-staminate structure. The coiled form of the mature anthers is achieved through the prolonged and spiral growth of the apical portions of the developing thecae. The coiling of the thecae in this manner results in a significant increase in volume devoted to pollen production in a relatively compact space. The two petaloid envelopes (or "cuculli") emerge as papillate processes on either side of the filaments of the two antepetalous stamens. Laminar growth of the cuculli proceeds such that both contribute equally in the formation of a common chamber surrounding all three anthers. Field and laboratory studies indicate that pollen is expelled from the chamber primarily through the apical terminus of a hose-like, slightly supervolute, extension of each cucullus through vibration of the entire staminal structure by certain pollen-collecting bees. Euglossine and xylocopine bees found "buzzing" the flowers of Cochliostema in the field were captured and observations using an SEM revealed an abundance of Cochliostema pollen deposited on the bees' hind legs. These data indicate that the cuculli of Cochliostema are, in many respects, functionally analogous to the poricidal thecae of many buzz-pollinated flowers, thereby confirming the predictions made by previous authors. These data also identify certain euglossine and xylocopine bees as probable vectors in pollen transfer between flowers of Cochliostema.

Key words: androecium, buzz pollination, Cochliostema, Commelinaceae, floral development