Domestication in cardamom has brought about significant changes in vegetative and reproductive traits and a shift in effective pollinators from native solitary bees to social bees. The shift in pollinators seems to be due to the availability of a large number of flowers for prolonged periods in cultivated cardamom that can attract and sustain social bees, rather than due to co-evolution of the flower and the pollinator.

Strobilanthes kunthianus (Acanthaceae) is a semelparous species with synchronized flowering and mast seeding once in 12 years. As semelparous plants have only one chance to reproduce, they are expected to develop effective strategies to prevent reproductive failure. The reproductive strategies of S. kunthianus were investigated by studying the floral traits, pollination biology, and breeding system that are critical for reproductive success. The species exhibits a series of floral traits: (1) gregarious flowering attracts a large number of Apis cerana indica, the major pollinator; (2) the stigma is sensitive to touch by the pollinator; in fresh flowers, the receptive surface faces the entry path of the incoming bee, facilitating pollen deposition; as an immediate response, the stigma curves backwards moving the receptive surface away from the path of the exiting bee, thus preventing autogamy and interference in pollen transfer; (3) flowers remain fresh for 2 days with receptive stigma and nectar and pollen reward. These traits render the species 100% pollination efficient to ensure a high seed set. As the species is self-compatible, the prevailing high degree of geitonogamous pollinations does not interfere with fruit set. The evolution of the adaptive floral traits has facilitated mast seeding in the species.

No abstract

Amomum subulatum (Zingiberaceae) is one of the major cash crops of the Eastern Himalayas. Our earlier study had shown that Bombus haemorrhoidalis is the only pollinator of A. subulatum. This was surprising in light of findings that other members of Zingiberaceae have at least a few pollinators for each plant species. We hypothesized that A. subulatum also is a generalist. Studies were carried out in six plantations of Northeast India. Floral visitors and their frequency were recorded. The pollination efficiency of each visitor was determined on the basis of pollen transfer to the stigma following a single visit of the pollinator to virgin flower. B. haemorrhoidalis, Apis cerana, Megachile lanata, Episyrphus balteatus (hover fly), Macroglossum stellatarum (hawk moth), and Aethopyga siparaja (crimson sunbird) visited the flowers of A. subulatum. Of these, B. haemorrhoidalis, M. lanata, and A. siparaja were effective pollinators. B. haemorrhoidalis was an important pollinator across all the plantations. Flower opening pattern influenced the pollination efficiency of visitors.Amomum subulatum / bumblebee / pollination efficiency / pollen robber / Eastern Himalayas / Zingiberaceae

Pollination ecology and the breeding system of four endemic species of Syzygium (S. heyneanum, S. travancoricum, S. laetum and S. mundagam) of the Western Ghats, India are investigated. The floral traits are used for ordination analysis to understand if the species form any cryptic groups and whether this grouping predicts the pollination syndrome and the breeding system. Pollinators were distinguished from frequent visitors by studying their efficiency to transfer pollen to the stigma or induce fruit set following their exclusive visit to virgin flowers. The species formed two groups in the ordination map: the S. heyneanum and S. travancoricum group and the S. laetum and S. mundagam group. The flowers of studied species attracted 3–23 species of animals during the day, but none were encountered during the night. Flowers of S. heyneanum and S. travancoricum were visited by a large number of insect species of which only a limited number turned out to be the pollinators. S. laetum and S. mundagam attracted two bird species apart from a few insect species. In S. laetum, although birds did not bring about pollination directly, their visits facilitated anemophily by releasing pollen to the air by causing physical disturbance to the flowers. In S. mundagam, both birds and wind were involved in pollination. S. heyeanum and S. travancoricum were fully self-compatible, whereas S. laetum and S. mundagam were partially self-compatible.