Floral biology and Breeding systems in Impatiens Grandis Heyne ex Wallich (Balsaminaceae)

Impatiens grandis Heyne ex Wallich is an evergreen, perennial shrubaceous balsam species facing a severe threat in the nature due to various factors. One of the factor is it own reproductive inefficiency and progeny recruitment. Hence the present investigation focused on floral biology and breeding systems of the species enlightening on phenology, pollen biology, pollen-pistil interaction, pollinators and breeding system to unravel the possible reasons for its rarity and endangerment. Flowers blooms between 0300-0500 h and anthers dehisced one day before anthesis confirmed the protandry. Pollen viability by FCR yielded 82% pollen grains are viable on the day of anthesis. Stigma showed 60% receptivity on the 3rd day of anthesis. Pollinators behavior in the wild confirmed honeybees made maximum visit (40%) followed by hawk moths (30%), butterflies (20%) and flies and ants (10%). The fruit set rate in natural pollination was very poor (30%) but artificial cross-pollination through xenogamy enhanced the fruit set up to 65%. Thus it is concluded that the plant is an obligate out-crosser and partially self-incompatible. Therefore, protandry, self-incompatibility, delayed stigma receptivity, pollinator’s scarcity, bottlenecks in reproduction and other ecological factors could be the reasons for narrow distribution in the Western Ghats.