Plants are essential to all life on Earth. They are special because they are able to make their own food by a process called photosynthesis where they take carbon dioxide from the atmosphere and turn it into sugar. The sugars can then be used for energy for growth and many more functions but the plant material provides the basis of almost all food chains.
Plants include a range of different groups that can all photosynthesize but can be very different physically and genetically. Included in the plant kingdom are the flowering plants or angiosperms, the gymnosperms – woody plants without flowers but with seed and cones, the ferns, lycophytes – similar to ferns but only have a single vein through each leaf, the bryophytes (mosses, hornworts and liverworts), and some algae.
All plants that grow flowers and fruit belong to the group known as the angiosperms. They the most advanced, diverse and abundant group of plants in the world and include around 200,000 plant species.
Gymnosperms are a group of woody, vascular plants with seeds but without flowers or fruit. The seeds of gymnosperm plants sit exposed on cones rather than enclosed in a fruit as they are with angiosperm plants.
Ferns and lycophytes are two groups of vascular plants without wood, seeds or flowers. They include over 12,000 species from ancient groups that once dominated the forests in many parts of the world.
The non-vascular plants include mosses, hornworts and liverworts and some algae. They are generally small plants limited in size by poor transport methods for water, gases and other compounds.
Plant physiology encompasses the study of plant form and function. As plants evolved to life on land they were required to evolve methods to extract CO², light, and water from the atmosphere and soil.