One morning as Leena strolled in her garden she noticed many small plants which were not there a week ago. She wondered where they had come from as nobody had planted them there. Explain the reason for the growth of these plants

This is because of seed dispersal. Seeds are dispersed away at different places from the parent plant through the means of wind, water, animals etc. Seed dispersal is important because:
1. it prevents overcrowding of plants at a particular place.
2. after the seeds are dispersed they get enough space and essential nutrients
3. seed dispersal is important because it helps plant to invade new habitats for wider distribution.