Seed Dispersal

About this topic

Plants spread seeds away from the parent to avoid competition and colonise new areas. Methods: wind (dandelion parachutes, sycamore wings), animals (hooked burrs stick to fur, fleshy fruits are eaten and seeds excreted), water (coconuts float), explosive release (pea pods, gorse) and gravity.

Fruit structures are adapted to the method used. Dispersal reduces overcrowding, increases gene flow and helps plants spread, which also helps explain invasive species.

Maple seeds spin like helicopters, coconuts float across oceans, and the squirting cucumber shoots its seeds explosively. Animals bury nuts and sometimes forget them, planting new trees. Spreading seeds reduces competition with the parent for light, water and nutrients and lowers the chance that disease will wipe out the whole family.

Dispersal is crucial for plants to colonise new places, such as islands after volcanic eruptions. Humans disperse seeds accidentally on shoes and clothes, which helps invasive weeds spread. Fruit evolved partly to be eaten, rewarding animals for transport. Students sometimes confuse dispersal with pollination; dispersal moves seeds, pollination moves pollen. Match each fruit structure, such as hooks, wings or fleshy tissue, with its method.