MORPHOLOGICAL ADAPTATIONS IN THE SEEDS OF RANGE GRASSES AND ITS ECOLOGICAL SIGNIFICANCE

摘要

'Seeds' of grasses are dispersal units comprising of spikeiets or fiorets with varying structure and form giving them a fluffy appearance 'Seeds' are chaffy in nature due to various appendages viz awns, hairs on the spikeiets, stiff bristles around the base and an attached sterile spikeiet. The car/opsis is enclosed in various envelopes commonly referred as husk Ai! the 'seeds' do not possess a caryopsis as majority of perennial tropical grasses produces higher proportion of empty seeds. Seeds with acaryopsis or seeds that germinate because of a caryopsis have also been referred as pure seed or pure germinating seed (PGS) by various workers. The present paper aims to i) describe the structure and form of chaffy seeds of 15 tropical range grasses ii) discuss the resource (weight) allocation in different parts of 'seeds' with regards to their form and to determine the weight differences in filled and empty 'seed' and iii) discuss the ecological significance of these morphological adaptations as these structures play vitally important roles in germination and also in preserving the viability of seeds for a longer period of time in a naturai rangeiand ecosystem.