The fabaceous plants rank second only to the grasses in value as ministrants to the economy of animal life, for they produce food for man and beast in vast abundance, and generally speaking, the aliments derived from this family are of the highest character in point of nourishing power, all of them contributing largely to the nourishment, not only of the muscular and bony framework, but in a peculiar degree also to the nervous system, owing to their richness in nitrogen and salts of phosphorus. In a majority of cases the fabaceous or leguminous plants have pinnated leaves, that is to say, each separate leaf consists of a series of symmetrical divisions united by a common stem.
Source: wiktionary