kasvikuntaa

Kasvikunta, or the plant kingdom (Plantae), is one of the major biological kingdoms comprising all land and freshwater vascular plants and many groups of algae. It is distinct from fungi, animals, and protists by its ability to produce food through photosynthesis, using chlorophyll to convert light energy into chemical energy. Plant cells possess rigid cellulose cell walls, chloroplasts, and specialized tissues such as xylem for water transport and phloem for nutrient transport. Reproduction can occur sexually, with flowers producing pollen and ovules, or asexually through runners, bulbs, and spores.

The kingdom is traditionally divided into several major clades, including bryophytes (mosses, liverworts, hornworts), vascular plants (monocots, dicots, gymnosperms), and green algae. Linnaeus first described Plantae in the 18th century, and subsequent botanists refined its composition. Modern molecular phylogenetics places the green algae groups within the broader Green Plant radiation, indicating that many aquatic algae share a common ancestry with land plants. The internal taxonomy of Plantae is dynamic, with recent revisions recognizing clades such as chlorophytes and streptophytes and reclassifying some groups traditionally treated as separate phyla.

Kasvikunta has global ecological importance; plants supply the majority of atmospheric oxygen, produce the bulk of food resources, and stabilize soil and water cycles. In many cultures, the plant kingdom is central to medicine, agriculture, and the arts. The diversity of form—from microscopic algae to towering sequoias—exemplifies evolutionary adaptation to a range of environments, illustrating the extensive morphological and biochemical innovation that characterizes the kingdom.