Auxin
![Native auxinsindole-3-acetic acid (IAA) is the most abundant and the basic auxin natively occurring and functioning in plants. It generates the majority of auxin effects in intact plants, and is the most potent native auxin. There are three more native — endogenous auxins[2]All auxins are compounds with aromatic ring and a carboxylic acid group:[3]4-Chloroindole-3-acetic acid (4-CI-IAA)2-phenylacetic acid (PAA)Indole-3-butyric acid (IBA)For representatives of synthetic auxins see chapter Synthetic auxins](/uploads/202502/14/Indol-3-ylacetic_acid.svg0706.png)
Auxins (plural of auxin /ˈɔːksᵻn/) are a class of plant hormones (or plant growth substances) with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by the Dutch scientist Frits Warmolt Went. Kenneth V. Thimann isolated this phytohormone and determined its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, Phytohormones, in 1937.