Reproductive biology of Actaea kashmiriana, an endemic medicinal plant species from the Himalaya: Implications for conservation and sustainable utilisation

Abstract

In prioritising conservation and sustainable use of medicinal plants, endemic species merit immediate research priority. Towards this endeavour, understanding the basic reproductive biology of endemic medicinal species is crucial to their successful conservation and sustainable utilisation. In this study, the reproductive biology of Actaea kashmiriana, an endemic medicinal plant species from the Himalaya has been investigated for the first time. The results reveal that species is herkogamous and protoandrous in nature. The pollen grains are prolate spheroidal, and pollen viability ranges from 79.4% to 80%. Under in vitro pollen germination, sucrose, boric acid and calcium nitrate were found to be the key nutrients. Stigma receptivity was maximum on 5th – 7th days of anthesis. Higher pollen-ovule ratio and outcrossing index reflects that Actaea kashmiriana is predominantly outbreeder. The results of pollination experiment show that the species is self-compatible and cross-fertile. Higher fruit set in xenogamous and open pollination treatments under natural conditions suggests cross-pollination as primary mechanism in the species. Presence of sweet nectar, aroma, floral display, and copious amount of pollen serve as main attraction and reward in the species and thereby attracting diverse pollinators, including 13 insect visitors belonging to 7 families and 10 genera. Based on the insect visitation efficiency and the pollen load, Bombus tunicatus, Bombus simillimus, Calliphora vomitoria and Eristalis tenax were found to be the dominant pollinators. Overall, the findings of present study have immediate implications in informing the conservation and sustainable utilisation of this medicinally prized endemic species, and also guide strategies for its habitat restoration in high-altitude Himalaya.