Evidence of functional specialization and pollination syndrome in Amomum subulatum Roxb. (Zingiberaceae)

Here we study functional specialization in Amomum subulatum in recruiting specific pollinators and in exhibiting pollination syndrome. Among diverse assemblages of animals, only native bumble-bees (Bombus braviceps Smith and Bombus haemorrhoidalis Smith) acted as effective pollinators in terms of visitation frequency, pollination efficiency, pollination potential index, pollen delivery and fruit set, whereas Udaspes folus and Macroglossum sp. acted as nectar robbers and Apis cerena and Episyrphus balteatus were pollen-resource wasters. Native bumble-bee were the sole functional group that increased the plant's fitness by being the 'most effective pollinators'. Foraging behaviour is the most crucial factor to bring about pollination in A. subulatum. Medium tongue length and proficient nectar-foraging behaviour make bumble-bees the most effective pollen vectors. Low secretion rate of nectar during morning hours could be the strategy of plants to bring about pollination effectively by instigating medium-tongued nectar foragers to move deep inside the labellum and the anther stigma column. A. subulatum may be categorized as an obligate specialist as it recruits only the bumble-bee as the most effective pollinator, thereby giving evidence of pollination syndrome.