A biopesticidal tree begins to blossom

Human civilization relies on biodiversity in many ways. Sudden changes in species biodiversity result in environmental changes that can modify weather patterns and therefore human civilizations.

Plants grow throughout their lives; this is called indeterminate growth, and it distinguishes plants from most animals. Although certain parts of plants stop growing (e.g., leaves and flowers), others grow continuously—like roots and stems.

Plants have a life cycle split between two multicellular stages: a haploid stage—with cells containing one set of chromosomes—and a diploid stage—with cells containing two sets of chromosomes. The haploid stage is the gamete-producing gametophyte, and the diploid stage is the spore-producing sporophyte.

Crop cultivation has a long history in human civilization, with records showing the cultivation of cereal plants beginning at around 8000 BC. This early plant breeding was developed primarily to provide a steady supply of food.

Plant hormones—or phytohormones—are chemical molecules that modulate one or more physiological processes of a plant. In animals, hormones are often produced in specific glands and circulated via the circulatory system. However, plants lack hormone-producing glands.