Vegetative Characteristics :
Habitat : Most of the members of this family are mesophytes.
Habit : The plants are annual herbs, some are shrubs, some other are trees. Some are weak stemmed that climb as twiners (Dolichos) or with tendrils (Pisum).
Root System : It is tap root system. The roots bear root nodules is which the symbiotic nitrogen fixing bacteria. Rhizobia are present.
Stem : It is aerial, erect, herbaceous or woody. In some plants stem is weak and prostrate or twinner (Dolichos) or a tendril Climber (Pisum, Lathyrus).
Leaf : Leaves are cauline, alternate, stipulate, petiolate and dorsiventral. The leaf base is pulvinous. They are simple or pinnately compound, the entire leaf except stipules in Lathyrus and terminal leaflets in Pisum are modified into tendrils. In ulex, the leaflets are modified into spines. Venation is Reticulate.
Floral characteristics :
Inflorescence : It is usually an axillary or terminal raceme (Crotalaria).
Flower : Flowers are bracteate, bracteoles may be present or absent, pedicellate, complete, zygomorphic, bisexual, pentamerous and perigynous. The thalamus is cup shaped.
Calyx : There are five sepals which are fused. The aestivation is valvate. The odd sepal is anterior in position.
Corolla : It consists of five petals which are free (Polypetalous). The corolla is papilionaceous. The posterior petal is largest and is called .Standard petal or Vexillum.. The two lateral petals are called .Wings or Alae.. The two boat shaped petals are called .Keel or Carina.. These are fused and encloses the essential organs. The aestivation is .descendingly imbricate..
Androecium : It consists of 10 stamens occasionally there may be only 9 stamens (Abrus, Dalbergia). Usually the filaments of the stamens unite to form two bundles of 9 + 1 (Diadelphous) as in Dolichos, Tephrosia, Pisum etc., or a single bundle (Monadelphous) as in Crotalaria, Arachis etc. Anthers are dithecous, introrse and dehisce longitudinally.
Gynoecium : It consists of monocarpellary, unilocular, half-inferior ovary. Usually many pendulous ovules are arranged in two vertical rows on marginal placentation. Style is long and curved at the apex. Stigma is capitate.
Floral Formula :
Pollination : As flowers are protandrous, usually cross pollination occurs. In lathyrus and pisum, there is self pollination.
Fruit : Mostly the fruit is a legume or pod (Pisum, Cajanus, Dolichos). In pterocarpus and Dalbergia it is a samara while in Arachis the pods are indehiscent and geocarpic.
Seed : It is non-endospermic and dicotyledonous. The cotyledons store proteins in large quantities.
