What are Legumes?

Legumen in Latin means seeds harvested in pods. Legume is derived from Legumen. Legumes belong to the botanical family Papilionaceae within the order Fabaceae (also called Leguminosae). The Fabaceae family includes over 750 genera and 16,000 – 19,000 species, making it the third largest family within the plant kingdom (Hoover et al. 2010). Familiar legumes aside from dry peas, dry beans, lentils, and chickpeas include soybeans, fava beans, peanuts, lupins, lucerne (alfalfa), clovers, and vetches.

Legumes are distinguished by three principal characteristics:

  1. A butterfly-shaped or papilionaceous flower
  2. Production of pods that contain seeds
  3. The ability to use atmospheric nitrogen to produce their own protein compounds, which is a result of a symbiotic relationship between nitrogen-fixing bacteria in the soil and the nodules in the legume roots

Legumes fall into the following two general categories:

Grain Legumes

  • Grain legumes are cultivated primarily for their seeds, or grains, which are harvested at maturity and marketed as dry products rich in protein. More than 40 species and myriad varieties of grain legumes are cultivated throughout the world. The major grain legumes grown in the U.S. include dry peas, lentils, chickpeas, soybeans, fava beans, lupins, vetches, and dry beans.

Forage Legumes

  • Forage legumes (mostly with small grains) are grown and used as feedstock for animals, either via grazing the crop or through the production of silage or hay, and for industrial purposes. Popular forage legumes include lucerne and clover.

What are Pulses?

Pulse, a name taken from the Latin word puls, meaning a thick soup. Considered environmentally friendly crops, pulses are less dependent on fossil fuels and reduce the need for fertilizer applications due to their ability to obtain much of their nitrogen from the atmosphere. Pulses also produce little crop residues and have low carbon to nitrogen ratios, which makes it very easy to rotate to the next crop using reduced tillage. Pulse crops have a hypogeal type of germination, which means that the plant seed leaves (i.e., cotyledons) remain below ground. This makes pulse crops more frost tolerant than soybeans or dry beans.

All pulses are considered as legumes but not all legumes are considered as pulses. According to the Food and Agriculture Organization (FAO), the term “pulse” can be used for only crops harvested solely for dry grain of leguminous plants, excluding crops harvested green such as green beans and green peas, which are considered as vegetables (FAO, 1994). In addition, crops used mainly for oil extraction such as soybeans and groundnuts (i.e., peanuts) are excluded from the definition. FAO identifies the following 11 crops as primary pulses:

  • Dry beans
    • Kidney bean
    • Haricot bean
    • Lima bean
    • Butter bean
    • Adzuki bean
    • Mungo bean
    • Golden, green and black gram
    • Urd bean
    • Scarlet runner bean
    • Rich bean
    • Moth bean
    • Tepary bean
  • Broad beans
    • Horse bean
    • Broad bean
    • Field bean
  • Dry peas
    • Garden peas
    • Field peas
  • Chickpeas
    • Bengal gram
    • Garbanzos
  • Cow peas
    • Black eye pea/bean
  • Pigeon peas
    • Pigeon pea, Cajun pea, Congo bean
  • Lentils
  • Bambara beans
    • Bambara groundnut
    • Earth pea
  • Vetches
  • Lupines
  • Pulses nes
    • Lablab or hyacinth bean
    • Jack or sword bean
    • Winged bean
    • Guar bean
    • Velvet bean
    • Yam bean