Plants, also called green plants, are multicellular eukaryotes of the kingdom Plantae. They form a clade that includes the flowering plants, conifers and other gymnosperms, ferns, club-mosses, hornworts, liverworts, mosses and the green algae. Plants exclude the red and brown algae, the fungi, archaea, bacteria and animals. There are suspected to be 300 to 315 thousand species of plants, of which the great majority are seed plants. (gymnosperms and angiosperms)
Plants, like other life forms in the Eukaryota domain, have cells with membrane-bound organelles.
Plants are made up of many cells, each serving different specific functions within the plant. All plant cells have cell walls made up of cellulose and a singular large central vacuole. Cell walls provide the cell with structural support, preventing them from bursting from large quantities of water entering the cell.
Plants are able to make their own food due to a process called photosynthesis carried out by the green pigment chlorophyll. Leaves are primary site of this process, where plants use water and carbon dioxide to convert light energy into sugars, releasing oxygen as a by-product. These sugars are used to power many metabolic processes within the plant with another process called respiration. This positions plants at the bottom of the food web, as heterotrophs like animals need to consume plant/animal matter to survive. An exception of this rule are holoparasitic plants, which contain no chlorophyll and thus cannot make their own food. Instead, they rely on other organisms to provide them with energy. (rafflesia, dodder plants)
- Soil Reliance
Most plants rely on a form of soil for support and water. Plants grow roots into soil, anchoring them and absorbing water. The soil also provides the plant with varying amounts of minerals, depending on soil composition. Some plants supplement their water resources with aerial roots that capture moisture from the air (orchids), and nitrogen by capturing and digesting small animals. (venus flytrap, pitcher plant)
Like animals, plants use energy stores (sugars generated from photosynthesis) and oxygen to release energy that powers metabolic functions. This process of respiration releases carbon dioxide as a by-product.