What are pulses?

Terminology

The term "pulse", as used by the United Nations' Food and Agriculture Organization (FAO), is reserved for crops harvested solely for the dry seed.
This excludes green beans and green peas, which are considered vegetable crops.
Also excluded are seeds that are mainly grown for oil extraction (oilseeds like soybeans and peanuts), and seeds which are used exclusively for sowing forage (clovers, alfalfa).
However, in common usage, these distinctions are not always clearly made, and many of the varieties used for dried pulses are also used for green vegetables, with their beans in pods while young.

Nitrogen fixation

Many legumes contain symbiotic bacteria called Rhizobia within root nodules of their root systems.  These bacteria have the special ability of fixing nitrogen from atmospheric, molecular nitrogen (N2) into ammonia (NH3).

Ammonia is then converted to another form, ammonium (NH4+).
This arrangement means that the root nodules are sources of nitrogen for legumes, making them relatively rich in plant proteins. All proteins contain nitrogenous amino acids. Nitrogen is therefore a necessary ingredient in the production of proteins. Hence, legumes are among the best sources of plant protein.

Classification

FAO recognizes 11 primary pulses.

1.Dry beans (Phaseolus spp. including several species now in Vigna)

Kidney bean, navy bean, pinto bean, haricot bean (Phaseolus vulgaris)
Lima bean, butter bean (Phaseolus lunatus)
Azuki bean, adzuki bean (Vigna angularis)
Mung bean, golden gram, green gram (Vigna radiata)
Black gram, urad (Vigna mungo)
Scarlet runner bean (Phaseolus coccineus)
Ricebean (Vigna umbellata)
Moth bean (Vigna aconitifolia)
Tepary bean (Phaseolus acutifolius)

2.Dry broad beans (Vicia faba)

Horse bean (Vicia faba equina)
Broad bean (Vicia faba)
Field bean (Vicia faba)

3.Dry peas (Pisum spp.)

Garden pea (Pisum sativum var. sativum)
Protein pea (Pisum sativum var. arvense)

4.Chickpea, garbanzo, Bengal gram (Cicer arietinum)

5.Dry cowpea, black-eyed pea, blackeye bean (Vigna unguiculata ) 

 

6.Pigeon pea, Arhar/Toor, cajan pea, Congo bean, gandules (Cajanus cajan)

7.Lentil (Lens culinaris) 

 

8.Bambara groundnut, earth pea (Vigna subterranea)

9.Vetch, common vetch (Vicia sativa)

10.Lupins (Lupinus spp.)

 

11.Minor pulses, including:

Lablab, hyacinth bean (Lablab purpureus)
Jack bean (Canavalia ensiformis), sword bean (Canavalia gladiata)
Winged bean (Psophocarpus tetragonolobus)
Velvet bean, cowitch (Mucuna pruriens var. utilis)
Yam bean (Pachyrhizus erosus)