The world’s simplest land plants

The world’s simplest land plants do not have

flowers or seeds. Instead, they reproduce by

releasing tiny cells called spores. Spores are

far smaller and simpler than seeds, and they

spread by water or on the wind. Seedless plants

include liverworts, mosses, and horsetails,

as well as all the world's ferns (see pages

30–31). Unlike seed plants, a seedless plant’s

life cycle alternates between two distinct plant

forms: one that produces spores, and one that

produces sex cells (sperm and eggs). Sometimes

the two plant forms look similar, but often they

are completely different, both in size and shape.