Groundnut (also known as peanut) (Arachis hypogaea L.), a native of South America, has
often been referred to as an unpredictable legume in the past (Gregory and Gregory, 1979;
Hammons, 1994). The genus Arachis contains 81 described species, categorized into nine
taxonomic sections, and includes both diploids and tetraploids belonging to either annual
or perennial type. The classification is based on morphology, geographical distribution
and cross-compatibility among the species (Valls and Simpson, 2005). The only cultivated
groundnut, Arachis hypogaea L., is further divided into two sub-species ‘hypogaea’ and
‘fastigata’ based on the branching pattern and the distribution of vegetative and reproductive
axes. Although it has been known to humankind for many centuries, its commercial cultivation
started only in early 1900, when it began receiving research attention..
