Table of Contents
The plant kingdom
The plant kingdom is a diverse group of organisms that includes both tiny algae and giant sequoias. Despite this diversity, all plants have a few things in common.
Plants are organisms that:
- Have bodies made of multiple cells.
- Can synthesize food in a process called photosynthesis.
- Usually can’t move.
Plants can be divided into two groups: those that make seeds and those that don’t.
Seedless plants
Plants in this group, called cryptogams, do not produce seeds.
Freshwater and marine algae
Green algae do not form true roots, stems, or leaves. This group gave rise to all land plants hundreds of millions of years ago.
Mosses and liverworts
Mosses and liverworts are the oldest land plants. They have a stem and structures resembling leaves and roots. Unlike other land plants, they lack a vascular system (a special tissue to transport water and nutrients).
Seed-producing plants
Members of this group, called gymnosperms, are the first vascular plants to produce seeds. The seeds, unlike in flowering plants, don’t have an outer covering.
Most members of this group are evergreen trees and shrubs. They are known for their needles (specialized leaves) and cones (where the seeds are kept).
Flowering plants
When you hear the word ‘plant’, you likely picture a member of this group. Called angiosperms, they form the most diverse and abundant division of the plant kingdom. Plants in this group can make flowers and fruits that enclose seeds.