Botany is the branch of biology that studies plants, from tiny mosses to giant trees.
Plants capture light energy, build tissues, move water and nutrients, reproduce in many different ways, and form the foundation of most ecosystems on Earth. Botanists study how plants are built, how they function, how they evolved, how they interact with other organisms, and how people use and protect them.
Plant cells contain structures such as cell walls, chloroplasts, and large vacuoles.
Learn MoreRoots absorb water and minerals while stems support plants and transport materials.
Learn MorePlants use light energy to make sugars from carbon dioxide and water.
Learn MoreFlowers, cones, spores, seeds, and vegetative growth help plants produce new generations.
Learn MorePlants have evolved structures and life cycles suited to deserts, forests, wetlands, and other habitats.
Learn MorePlants provide food, oxygen, shelter, and habitat while influencing soils and climate.
Learn MoreLike animals, plants are made of cells, but plant cells have several distinctive structures. A rigid cell wall made mainly of cellulose helps support each cell, while a large central vacuole stores water and helps maintain internal pressure. Chloroplasts contain chlorophyll and other pigments that capture light for photosynthesis. Different plant cells become specialized for jobs such as protection, transport, growth, and food storage.
Roots anchor many plants and absorb water and dissolved minerals from the soil. Tiny root hairs greatly increase the surface area available for absorption. Stems hold leaves and reproductive structures where they can reach light, air, or pollinators, and they contain transport tissues. Xylem moves water and minerals mainly upward from the roots, while phloem carries sugars and other organic materials to growing or storage tissues throughout the plant.
Photosynthesis allows plants and some other organisms to store light energy in chemical form. In chloroplasts, light-dependent reactions capture energy, while other reactions use that energy to help build sugars from carbon dioxide. Water supplies electrons and hydrogen, and oxygen is released as a by-product. The sugars produced can be used immediately for energy or converted into substances such as starch and cellulose for storage and growth.
Plants reproduce in many ways. Flowering plants produce pollen and ovules, and after fertilization many develop seeds enclosed within fruits. Conifers produce seeds in cones, while groups such as ferns and mosses reproduce with spores during parts of their life cycles. Some plants can also reproduce without seeds through runners, bulbs, tubers, cuttings, or other forms of vegetative growth, creating new plants from existing tissues.
Plant structures often reflect the conditions in which a species lives. Cacti and other desert plants may store water and reduce leaf surface area, while rainforest plants may have broad leaves suited to low-light environments beneath a canopy. Aquatic plants can have flexible stems or air-filled tissues, and alpine plants may grow low to the ground to avoid strong winds and cold. These features are the result of evolution acting over many generations.
Plants are primary producers, meaning they convert external energy into organic matter that can support food webs. Herbivores eat plants, predators may depend on those herbivores, and decomposers return nutrients from dead plant material to soils and water. Plant roots can reduce erosion, forests can influence local water cycles, and vegetation stores carbon in living tissue and soil. Because plants support so many ecological processes, changes in plant communities can affect entire ecosystems.