Pollination biology of Indotristicha ramosissima (Podostemaceae: Tristichoideae)

Floral morphology, phenology and mode of pollination have been studied in Indotristicha ramosissima (Wt.) van Royen. Although the plants are submerged, self-pollination (autogamy) occurs above water. This is aided by considerable elongation of the pedicel (20 mm) prior to pollination. The filaments of the stamens also elongate rapidly (∼6.5 mm/h) before and after pollination. The flowers are typically trimerous. Each anther contains 1743 ± 187 pollen grains. These are spherical, multiporate, 3-celled and ∼97% fertile at the time of shedding. Germination of pollen on the stigma and the growth of pollen tubes have been traced in both naturally and manually (self- as well as cross-) pollinated pistils. The pollen:ovule ratio is ∼72:1 and the ovule: seed ratio is ∼2:1. Mature fruits are 8 or 9 ribbed and open by 2 or 3 longitudinal slits that release ∼32 seeds.