Plant Biology and Botany

Botany is the scientific study of plants, organisms that, with few exceptions, make their own food through photosynthesis. In this process chloroplasts use the energy of sunlight to convert carbon dioxide and water into sugars, releasing oxygen as a by-product. This ability places green plants at the base of most food chains and makes them central to the cycling of carbon and oxygen through the biosphere.

Plants are built from cells whose stiff walls, large central vacuoles and chloroplasts distinguish them from animal cells. Materials move into and out of cells by diffusion and active transport. In vascular plants, two specialised tissues conduct materials over long distances: xylem carries water and dissolved minerals upward from the roots, while phloem distributes the sugars made in the leaves. Growth and development are coordinated by plant hormones that influence responses to light, gravity and the environment.

Reproduction varies across plant groups. Flowering plants reproduce sexually through flowers, whose structures produce pollen and egg cells; after fertilization the ovule develops into a seed and the surrounding ovary into a fruit. The plant kingdom ranges from non-vascular bryophytes such as mosses and hornworts, through seedless vascular plants including the club mosses that formed ancient forests, to the seed plants that dominate most modern landscapes. Meiosis underlies the formation of the reproductive cells that make this variety of life cycles possible.

Frequently asked questions

What is photosynthesis?

Photosynthesis is the process by which plants use sunlight to convert carbon dioxide and water into sugars, releasing oxygen. It supplies energy for the plant and most other life.

What do xylem and phloem do?

Xylem transports water and minerals from the roots upward, while phloem carries sugars made in the leaves to other parts of the plant. Together they form the vascular system.

What is the function of a flower?

A flower is the reproductive structure of flowering plants. It produces pollen and egg cells, and after fertilization it develops seeds enclosed in a fruit.