Cowpeas are one of the most important food legume crops in the semi-arid tropics covering Asia, Africa, southern Europe and Central and South America. A drought tolerant and warm weather crop, cowpeas are well-adapted to the drier regions of the tropics, where other food legumes do not perform well. It also has the useful ability to fix atmospheric nitrogen through its nodules, and it grows well in poor soils with more than 85% sand and with less than 0.2% organic matter and low levels of phosphorus. In addition, it is shade tolerant, and therefore, compatible as an intercrop with maize, millet, sorghum, sugarcane, and cotton. This makes cowpea an important component of traditional intercropping systems, especially in the complex and elegant subsistence farming systems of the dry savannas in sub-Saharan Africa (Blade, 2005).
Southern peas are a common food item in the southern United States, where they are sometimes called crowder peas. They are so named because they appear to be crowded into their pods. The crowding causes them to have a squarish shape rather than round.
Black-eyed, Brown Crowder, Colossus, Mississippi Silver,Pinkeye Purplehull, Knuckle Purplehull, Big Boy, Cream 12, Cream 40, Ladyfinger, Sadandy, White Acre and Zipper are the different varieties.