1. Diagnostic features :
- Mostly herbs, rarely shrubs or trees, often climbing.
- Leaves alternate, stipulate, simple, or imparipinnately compound.
- Flowers bisexual, zygomorphic, corolla papilionaceous, aestivation descending- imbricate, posterior petals outermost, stamens 10 or 9, monadelphous or diadelphous, rarely free.
- Gynoecium monocarpellary, unilocular with marginal placentation.
- Fruit a legume or pod.
2. Distribution :
- Includes about 482 genera and nearly 7200 species.
- Worldwide in distribution and grow abundantly in tropical, sub-tropical and temperate regions, of both the northern and southern hemispheres.
- Found in plains as well as in hilly regions reaching up to 8000 feet.
3. Vegetative characters:
- Habit: Show a wide range of variation in their habit. Usually herbs (Vicia, Pisum), shrubs (Cajanus, Ulex) or trees (Butea, Dalbergia). Climbers are also most common (Pisum, Lathyrus).
- Roots: Branched tap root system. Root nodules containing nitrogen fixing bacteria.
- Stem: Aerial, usually erect, sometimes climbing or twiners, branched, cylindrical or angular, herbaceous or woody, solid or fistular.
- Leaf: Cauline and ramal, alternate rarely opposite or whorled, stipulate or exstipulate, stipules leaf like (Pisum) simple (Cajanus) or pinnately (Pisum) or palmately (Crotalaria) compound, terminal leaflet modifies into a tendril in Lathyrus, Pisum, Vicia.Venation unicostate (Pisum) or multicostate (Crotalaria) reticulate.
4. Floral characters.
a)Inflorescence: racemose usually araceme (Pisum, Lathyrus), sometimes spikes (Uraria), panicles (Dalbergia), solitary axillary (Cicer) or terminal.
b) Flower: pedicellate, bracteates, sometimes bracteolate (Sesbania), complete, hermaphrodite, zygomorphic, pentamerous, hypogynous or perigynous.
c) Calyx: sepals-5, gamosepalous, persistent, valvate or imbricate, odd sepal anterior.
d) Corolla: petals-5, very unequal and papilionaceous (i.e. one posterior petal is very large and called standard, 2 lateral wings and two innermost, smallest united petals known as keel), aestivation vexillary or descending imbricate.
e) Androecium: stamens-10, diadelphous usually 9+1 (Pisum) or sometimes 5+5 (Smithia). Only 9 monadelphous stamens are present in Dalbergia. Anthers usually two-celled, introse, basi or dorsi fixed, dehiscing by longitudinal slits. In Sophora all the stamens are free.
f) Gynoecium: carpel one, ovary superior, unilocular, with many ovules in two rows, placentation marginal, style and stigma simple.
g) Fruit: usually a legume or sometimes indehiscent (Melilotus).
h) Seeds: usually non-endospermic. Embryo is large and curved.
i) General floral formula with floral diagram:
5. Economic importance
i) Pulses and vegetables:
- Almost all pulses belong to this family.
- They are sources of protein.
- Examples: Cajanus cajan (arhar- pigeon pea), Cicer arietinum (gram or chana), Pisum sattivum (matar or pea), Dolichos lablab (semi or bean), Glycine max (soyabean or bhattamas), Phaseolus aureus ( mung).
- Dalbergia sissoo, Butea and Pterocarpus provide excellent wood for various building purposes, furnitures and fuel.
- Oil obtained from the seeds of the plants are used for various purposes.
- Some are edible (Arachis hypogea– ground nut, Glycine max– bhattmas), some are used for preparing vegetable ghee (soyabean oil), some (ground nut oil) for preparing soap and cosmetics.
- Oil cake is used as fodder.
iv) Green manuring:
- Crotalaria junceae, Medicago sativa, Trifolium pratense, Sesbania aculenta (Dhaicha), etc are used to increase the nitrogen content of the soil.
- Yellow dye obtained from Butea monosperma.
- Blue dye obtained from the flowers and seeds of Clitoria ternatea.
- Pisum sativum, Lathyrus, Butea, Clitoria, Clianthus dampieri (Glory pea) are used as ornamental plants.
- Crotalaria, Sesbania , etc are used as the source of fibres which is used for making cords, bags and ropes.
- Glycyrrhiza glabra, Clitoria and Teramnus labialis are used as medicines for various diseased condition.