The peanut, or groundnut (Arachis hypogaea), is a species in the legume or "bean" family (Fabaceae). Despite its name and appearance, the peanut is not a nut according to the botanical definition (Britannica Academic Edition).
The peanut was probably first cultivated in the valleys of Peru (University of Georgia 2004).It is an annual herbaceous plant growing 30 to 50 cm (1.0 to 1.6 ft) tall. The leaves are opposite, pinnate with four leaflets (two opposite pairs; no terminal leaflet), each leaflet 1 to 7 cm long and 1 to 3 cm broad. The flowers are a typical peaflower in shape, 2 to 4 cm across, yellow with reddish veining (Young, 2006).
Hypogaea means "under the earth", because after pollination, the flower stalk bends downward, and the mature fruit develops underground -- the peanut – a classical example of "geocarpy." Pods are 3 to 7 cm (1.2 to 2.8 in) long, containing 1 to 4 seeds (Young, 2006).