Floral Biology of Aconitum heterophyllum Wall.: A Critically Endangered Alpine Medicinal Plant of Himalaya, India

Abstract

Aconitum heterophyllum Wall. is a critically endangered wild medicinal herb of alpine Himalaya and cultivation is recommended owing to its large demand in the herbal market and to ensure the conservation of wild habitats. Therefore, observations on floral biology, pollen germination, pollination, and fruit and seed setting after implying different breeding systems were carried out for its successful domestication and improvement in cultivation practices. The study reveals that the plants grown in hothouse conditions showed considerable variation in the production of flowers and seeds. Flowering occurs from the second week of September to late October, with 20 days of peak flowering. Anthers dehisced longitudinally between 7:30 and 11:00 AM, strongly dependent on higher temperature. The pollen grains per anther varied between 2000 and 6000, which means an average of 80,000 pollen grains per flower. Nectar production begins at anther dehiscence and coincides with maximum stigmatic receptivity. Bees were observed as pollinators. Pollen germination and pollen tube elongation were maximum in 5% sucrose. Controlled pollination revealed that this species is self-incompatible, although few fruits developed from selfing. Such fruits were smaller than the fruits produced by open pollinated and from hand-crossed flowers and most aborted early in development.