How Many Species of Plants Are There?
There are about 375,000 species of plants, with more being discovered each year. This includes seed plants, bryophytes, ferns and relatives of ferns called fern allies. Some 287,655 species of plants have been identified, of which 258,650 are flowering and 15,000 bryophytes (liverworts, hornworts, and mosses). All plants are photosynthetic, utilizing carbon dioxide, water and light energy to produce oxygen and sugars. Within each cell are numerous organelles called chloroplasts which perform this task. Chloroplasts are thought to be ancient cyanobacteria that were absorbed by the larger eukaryotic cells which constitute plants. Plants consist of two main groups; green algae and land plants. Other types of algae, such as red algae and brown algae, were initially identified as plants, but later classified outside the kingdom Plantae. These latter organisms are part of the same unranked group as plants, Archaeplastida, but are usually not referred to as plants except in a colloquial sense
