Study of floral biology of insulin plant Costus pictus D. Don

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Abstract

This study deals with the reproductive biology of the plant Costus pictus D. Don, commonly known as the “Insulin plant” with potential medicinal properties.  It provides information regarding all whorls of flower. Pollen and stigma morphology is studied through SEM analysis. The present studies were conducted in the field and laboratory, department of Botany, RG PG College, Meerut on 50 inflorescence spikes. The inflorescence cone bear bracts which have dark green colour extra-floral nectaries. Flowers of C.pictus D. Don are zygomorphic, hermaphrodite with a labellum of five fused sterile stamens. A single fertile petaloid stamen is present on petaloid structure. Bilobed stigma appendage is attached to the wet bilamellate stigma. Flower shows co-occurrence of stamen and stigma. Pollen grains are some what asymmetrical in shape due to large size. Pollen are pantoporate as examined in SEM analysis. Pollen surface is found to be  psilate during SEM examination but pores are ornamented. Floral nectary is present inside, above  the ovary in prolongation region. Stigma receptivity was high in mature flowers while bud stage showed very few bubbles. The present study will help  scientists, taxonomists, and students to study the floral biology of flowers and inflorescence for identification, conservation, and breeding purposes.