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The present thesis deals with the reproductive biology and in vitro culture of Abroma augusta. The plant, belonging to the family Sterculiaceae, is a large perennial shrub, reaching a height of 6 to 7 m. It sends off sparse, slender, somewhat horizontal, shaggy branches bearing series of erect fruits and showy, maroon pendulous flowers produced terminally in scorpioid cymes. Abroma augusta is known to occur in Nepal, Bhutan, China, Philippines, Indonesia and Malaysia. In India, the species is reported to be widely distributed throughout the hot and moist parts of the country, from Punjab and Uttar Pradesh, eastwards to Sikkim, Arunachal Pradesh, Assam, Meghalaya and Tripura, ascending to 1200 m and southwards in peninsular India. In wild state, Abroma augusta is found to grow sporadically often as isolated individuals and sometimes in small populations growing as escapes along roadsides, on banks of ponds, left-out private plots, fallow lands, etc. Rarely a few are also seen to be grown in gardens for the showy, maroon lantern flowers. Abroma augusta is a valuable medicinal plant and has long been used in our indigenous system of medicine. The commercial drug is derived from profusely branched woody roots. The drug is considered to be a uterine tonic, an emmenagogue, an abortifacient and antifertility agent. It shows contractile action on the uterus and is used for the treatment of dysmenorrhoea, amenorrhoea, sterility and other menstrual disorders. Presence of the alkaloid, abromine together with some alkaloidal bases (choline, betaine) and some phytosterols (βsitosterol, stigmasterol), a basic compound (picrate) and a fixed oil have been identified in of the plant. Due to increasing human populations leading to habitat destruction and other anthropogenic effects, Abroma augusta has become almost threatened in nature, at least in this part of the country. Only a limited number of individuals were found to grow in natural habitats. The study of the reproductive biology of any plant is most essential to formulate suitable strategies for its conservation and cultivation. Therefore, to unravel the reproductive biology of any plant, details of its pollination biology as well as those of its seed biology are to be worked out. The study of the pollen biology of a plant, its pollen vectors, pollination mode, stigma receptivity, floral attractants and rewards, etc. come under the purview of pollination biology. The seed biology of a plant is an even broader domain. Seed production, seed predation, seed dispersal, germination behaviour, dormancy (if any) and dormancy breaking treatments, vivipary (if any), etc. are important parameters in understanding the seed biology of a plant species. However the reproductive biology of Abroma augusta have not yet been worked out so far. There is no report of any work done on the pollination biology of Abroma augusta, excepting the mention made by van der Pijl (1953) that Milichiidae are its floral visitors in Java. Also, various aspects of seed ecology of the species are yet to be worked out. Protocols for in vitro culture of the species are hitherto unknown. In view of the medicinal values, additional economic prospects and threatened status of Abroma augusta, the present work involving the detail studies in its reproductive biology and in vitro culture was undertaken to formulate suitable strategies for successful conservation and propagation of the invaluable medicinal plant. The work is based on wild plants growing in small populations or as isolated individuals in and around Burdwan, Santiniketan and Medinipur, together with four plants grown in the experimental garden of Botany Department, Burdwan University. The thesis comprises altogether five chapters. In Chapter-I, the Introduction, at first the significance of the knowledge of reproductive biology and in vitro culture for conservation and propagation of economically important threatened plants has been mentioned followed by the nomenclature, synonymy and systematic position, geographic distribution, habit, ecological settings, economic importance with special reference to medicinal values, bioactive compounds, significance of the study of the reproductive biology of Abroma augusta and a brief review of previous works done in related taxa have been dealt with briefly. Chapter-II deals with the details of the material on which the present work is based and the general methodologies adopted for the investigations. Chapter-III encompasses the overall observations and discussions which have been subdivided into following four sections. Section III A, entitled Floral biology and pollination ecology, includes the details of the age of attainment of reproductive maturity, flowering phenology, flower opening, flower structure, flower longevity, anther dehiscence, pollen production, pollen morphology, pollen viability, floral visitors vis-a-vis pollinators, activity of the pollinators in and around the flower, floral attractants and rewards, pollen presentation and dispersal, stigma receptivity, homogamy, anthesis, pollination syndrome, ovule production, pollen-ovule ratio and breeding system of Abroma augusta. In Section III B, entitled Post-pollination developments, accounts of fruit-flower ratio, percentage of fruit-set and stages of fruit development since pollination have been given. Section III C is entitled as Seed ecology. In this section, seed production, seed-ovule ratio, seed dispersal, seed predation, seed structure, vivipary of premature seeds, dormancy and scarification requirement of freshly harvested mature seeds have been dealt with. Section III D, entitled as In vitro culture, includes details of the protocols formulated for callogenesis of Abroma augusta from seedling explants as well as explants from mature individuals. However, it must be mentioned that in spite of repeated efforts, no regeneration of the calluses could be obtained. Finally Chapter-IV and Chapter-V include the concluding remarks and the references respectively. .