Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as flowering plants, conifers, ferns, mosses, and green algae, but do not include seaweeds like kelp, nor fungi and bacteria. The group is also called green plants or Viridiplantae in Latin. They obtain most of their energy from sunlight via photosynthesis using chlorophyll contained in chloroplasts, which gives them their green color. Some plants are parasitic and may not produce normal amounts of chlorophyll or photosynthesize. Precise numbers are difficult to determine, but botanists estimate there are 300–315 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants.