Botany, plant science(s), or plant biology (from Ancient Greekβοτάνηbotane, "pasture, grass, or fodder" and that from βόσκεινboskein, "to feed or to graze"), is a discipline of biology and the science of plantlife. Traditionally, the science included the study of fungi, algae, and viruses. A person engaged in the study of botany is called a botanist.
Botany covers a wide range of scientific disciplines including structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary relationships among taxonomic groups. Botany began with early human efforts to identify edible, medicinal and poisonous plants, making it one of the oldest branches of science. Nowadays, botanists study about 400,000 species of living organisms.
The beginnings of modern-style classification systems can be traced to the 1500s–1600s when several attempts were made to scientifically classify plants. In the 19th and 20th centuries, major new techniques were developed for studying plants, including microscopy, chromosome counting, and analysis of plant chemistry. In the last two decades of the 20th century, DNA was used to more accurately classify plants.
In the APG II system (2003) for the classification of flowering plants, the name asterids denotes a clade (a monophyletic group).
Most of the taxa belonging to this clade had been referred to the Asteridae in the Cronquist system (1981) and to the Sympetalae in earlier systems. The name asterids (not necessarily capitalised) resembles the earlier botanical name but is intended to be the name of a clade rather than a formal ranked name, in the sense of the ICBN. This clade is one of the two most speciose groups of eudicots, the other being the rosids. It consists of:
Note : “ + ....” = optional as a segregate of the preceding family.