Seeds and Spores
♥ Plants which live on land are not very mobile. If they are going to colonize new habitats they need some way of dispersing themselves.
♥ Flowering plants and conifers disperse themselves as seeds. These contain the embryo plant with its food supply. They are surrounded by a fruit which
helps them to disperse by wind, by water, by using animals or by explosion.
♥ The method of dispersal used usually depends upon where the plant is normally found growing; for example, open windy places or near water.
♥ Not all land plants use seeds to disperse themselves; other plants use spores.
♥ Spores are microscopically small so that they can be carried easily by the wind.
♥ The mosses and liverworts are small simple plants which produce spore cases on a stalk so
that the spores are easily caught by the wind.
♥ The spore capsule and spores of liverworts and mosses are the result of a sperm cell
fertilizing an egg cell on the parent plants.
♥ Fertilization in these plants needs water for the sperms to swim in.
♥ When the spores of these plants land in a suitable habitat, they germinate and grow into new
liverworts or mosses.
♥ The fern plants also produce spores in spore cases which grow underneath their fronds.
♥ When spores of ferns germinate they do not grow into a new fern plant, they grow into a small plant called a prothallus.
♥ It is on the prothallus that fertilization takes places. The result of fertilization is a new fern plant.
♥ Fertilization on the prothallus requires water for the sperms to swim in.