Reproductive biology of Polypleurum stylosum (Podostemaceae)

Floral biology, pollination, pollen-pistil interaction and fruit development were studied in Polypleurum stylosum var. stylosum and var. laciniata growing attached to rocks in rivers and in the laboratory. Floral development and morphology are similar in both varieties but there are differences in flower bud size, number of pollen grains, ovules, seeds and ovule : seed ratio. Both varieties are self-compatible and predominantly self-pollinated. The interlocking of sex organs within a flower is an adaptation for self-pollination although crosspollination cannot be ruled out. Germination of pollen on the stigma and entry of pollen tubes into the ovules have been observed. Fruits appear mature in an incredibly short period of 4-5 days after pollination.