Legumes incorporate more protein than other plants, possibly because N is not limiting. Certain grass grain - legume combinations provide a balanced amino acid composition.
Plants are allotetraploids.
After fertilization, pedicels curve downward and developing fruit is pushed into soil. Pea in split-pea soup Origin possibly in India. Supposedly a lot of potential for development of high-yielding cultivars but not much being done, presumably due to lack of demand. Earliest records are from Turkey about 7400 ybp. Efforts to increase productivity have been relatively unsuccessful.