Floral morphology and reproductive biology of medicinal plants: Costus (Costaceae)
Amita Sharma and Stuti Sharma
Floral morphological studies were conducted on Costus pictus D. Don and Costus speciosus (Koening) sm, belonging to family Costaceae. Flowering period was found to be from May to November. Inflorescence was born on a leafy shoot at a terminal position in both the species. Colour of bract is green in C. pictus and dark red in C. speciosus. Extra floral nectary is present on the bracts in form of vertical dark lines. A single petaloid labellum, mono petaloid fertile stamen and inferior apparent 2- locular ovary in C. pictus and 3-locular ovary in C. speciosus are found. The thin and thread-like style is positioned between the thecae of the fertile stamen. Two lobed stigma bears appendages. Placentation is parietal in C. pictus and axile in C. speciosus. During the whole flowering period, ants were the only pollinators to visit the flower and inflorescence. The present study highlights the key for identification of the species and their pollinators.