Fabaceae (Leguminosae) : Morphological Diversity

Fabaceae (Leguminosae) : Morphological Diversity

Fabaceae (Leguminosae)

Systematic Position

Class- Dicotyledonae

Subclass- Polypetalae

Series- Calyciflorae

Order- Rosales

Family- Leguminosae (Fabaceae)

3 Subfamilies according to Bentham and Hooker





Distribution of Fabaceae –

Large family containing more than 600 genera and 13000 species distributed throughout the world except arctic region. Over 100 genera and 800 species of Fabaceae have been reported from India.

Habit- Mostly Herbs, shrubs, trees and climbers. Clitoria, Dolichos, Phaseolus etc are twiner.

Crotolaria is shrub. Mellettia is a woody climber. Sesbania is  a small tree whereas species of Dalbergia, Pterocarpus are large trees.

In Lathyrus aphaca all the leaflets are modified into tendrils and the function of photosynthesis is performed by the foliaceous stipules.

Flowers of Fabaceae –

In Fabaceae flowers arebBracteate, Bracteolate, zygomorphic, hermaphrodite, pentamerous and hypogynous or perigynous.

Corolla- papilionaceous, posterior largest petal is called standard in Fabaceae .lateral petals are known as wings and the two anterior petals are united to form the keel which encloses the stamens and carpel.

Calyx- sepals 5, gamosepalous, valvate or imbricate aestivation in bud, odd sepal is usually anterior.

Androecium-  In Fabaceae ten, diadelphous, nine are united and the tenth  posterior remains free.

Gynoecium- Monocarpellary, superior or partly inferior unilocular ovary. Ovules many, marginal placentation, style simple, stigma capitate or terminal.

Fruit- Pod or legume dehiscing by one or both the sutures into two halves.

Seeds- nonendospermic or scanty endosperm with large curved embryo.

Fabaceae :Pisum sativum

Habit- Annual herb, cultivated.

Root- Tap root, branched with nodules containing nitrogen fixing bacteria.

Stem- herbaceous, weak, climbing with the help of leaf tendrils, branched.

Leaf- Ramal and Cauline, alternate, petiolate, upper leaves modified into tendrils, stipulate, entire, acute, green.

Seeds- nonendospermic or scanty endosperm with large curved embryo.

Inflorescence- Racemose or solitary axillary.

Flower- Pedicillate, Zygomorphic, irregular, bisexual, white or pink, complete, hypogynous

Calyx- Sepals 5, gamosepalous, valvate, green and hairy.

Corolla- Petals 5, 2 wings, 2 keels united, keels shorter than wings encloses the pistil and stamens, corolla papillionaceous, white or pink, vexillary aestivation.

Androecium- Stamens 10, diadelphous, nine fused in the form of tube around the ovary and the tenth is posterior and free, anthers dithecous, basifixed, introse.

Gynoecium- Monocarpellary, ovary superior, unilocular, marginal placentation, ovules many, style bent and long, stigma simple, terminal and hairy.

Fruit- Legume (Pod).

Seed- Broad, rounded, green.


Common plants : –Cassia fistula (Golden shower tree) – –Bauhinia variegata(kachnara) – –Caesalpinia pulcherrima (peacock flower) – –Delonix regia(gulmohar) –Tamarindus indica(imli)


152 genera and 2800 species distributed in tropical and subtropical regions. In India 23 genera and 80 species.

Vegetative characters-

mostly trees (Tamarindus indica, Cassia fistula), shrubs (Parkinsonia) or rarely herbs (Some species of Cassia e.g C. tora and C. absus).

Leaves- Alternate, stipulate, unipinnate (Cassia), or bipinnate (Tamarindus, Delonix).

Inflorescence- Racemes or panicle.

Flowers- large and showy, bracteate, complete, zygomorphic, bisexual, pentamerous and hypogynous.

Calyx- 5 sepals, imbricate or valvate aestivation, petaloid in Saraca and the upper two sepals are united in Tamarindus.

Corolla- 5 free petals, imbricate. In Tamarindus only the upper three petals are developed and the two lower are reduced to scales. Petals are absent in Saraca.

Androecium- Diplostemonous with two whorls of five stamens each. All the ten stamens are perfect in caesalpinia and Parkinsonia, but often some of the stamens are reduced to staminodes or altogether absent. E.g In cassia 5-7 stamens and in Bauhinia 3-5 stamens are perfect and the remaining are reduced to either staminodes or are absent. In Tamarindus, only 3 stamens are perfect while others are reduced to small bristles. The anthers are dithecous, introrse and dehiscing longitudinally or sometimes by longitudinal pores as in several species of Cassia.

Gynoecium- Monocarpellary , superior ovary, unilocular, marginal palcentation, ovule in two rows, simple style with capitate stigma.

Fruit- Pod

Seeds- endospermic or non-endospermic with a large embryo.


Cassia fistula

Stem-   woody, aerial, erect, cylindrical, branched, solid and  smooth .

Leaf- alternate, stipulate, compound, unipinnate and paripinnate, petiolate,ovate,entire,glaborous.

Inflorescence- Axillary, pendate, racemose raceme.

Flower- Bracteate, pedicillate, complete, Zygomorphic, pentamerous, hypogynous.

Calyx- Sepals 5, polysepalous, Quinquincial, petaloid.

Corolla- petals 5, polypetalous, imbricate, yellow.

Androecium- stamens 10 in two whorls of two each, anterior 3 stamens are reduced to staminode, dithecous, dorsifixed, introse.

Gynoecium- Monocarpellary, ovary superior, unilocular, marginal placentation, ovules many, style short, stigma capitate.

Fruit- Legume

Floral Formula


Common plants:

Acacia nilotica(kikar or babul)

-Mimosa pudica(touch-me-not)

-Albizzia lebbek(sirin)

Acacia nilotica


56 genera and 2800 species distributed in tropic al and subtropical regions. In India 15 genera and 72 species in tropical and subtrropical Himalaya.

Vegetative characters- 

Mostly trees (Acacia, Albizzia), rarely herbs (Neptunia), shrubs (Dicrostachys) or woody climbers climbing with the help of leaf tendrils (Entada).

neptunia oleraceae, entada

Stem- of climbing species (Entada) show anomalous growth in thickness and they become winged.

Leaves- alternate, stipulate and bipinnate, unipinnate in (Inga). In some species of Acacia the stipules are modified into thorns. The leaves of Mimosa and Neptunia are sensitive to touch.

Inflorescence- flowers are condensed into dense head but sometimes they are racemose.

inflorescence in Fabaceae

Flower- Bracteate, sessile, complete, actinomorphic, bisexual. Mostly pentamerous, sometimes three-, four or six-merous e.g (Mimosa )and hypogynous.

Calyx- 4-5 sepals united into short tube, valvate aestivation or rarely imbricate.

Corolla- 4-5 petals subconnate at the base to form a short tube. Valvate aestivation.

Androecium- number and cohesion of stamens shows much variation. In Acacia numerous stamens, free, In Albizzia indefinite stamens monoadelphous at the base. In some species of Mimosa the stamens are as many as petals.

The filaments are long, filiform. The anthers are dithecous, introrse, versatile, dehiscing longitudinally.

Gynoecium- single carpel, superior ovary, unilocular with many ovules. Marginal placentation, style and stigma are one.

Fruit- Legume, Lomentum in Acacia.

Seeds- scanty endosperm or without any endosperm.

Acacia nilotica

Acacia nilotica

Stem-  aerial, erect, cyliindrical, branched, solid, hairy.

Leaf- Alternate, stipulate, stipule free-lateral modified into thorns, compound, bipinnate and paripinnate, petiolate, leaflets subsessile, oblong, entire, acute, green, glaborous.

Inflorescence- Capitate

Flower- Bracteate, sessile, complete, actinomorphic, hermaphrodite, tetra-pentamerous, hypogynous, cyclic.

Calyx- 4-5 sepals, gamosepalous, valvate, membranous.

Corolla- 4-5 petals, gamopetalous, valvate.

Androecium- Stamens indefinite, polyandrous, filaments long, dithecous, dorsifixed, introrse.

Gynoecium- Monocarpellary, ovary superior, unilocular with amny ovules, marginal placentation, stigma capitate.

Fruit- Lomentum.

fruit if Fabaceae

To know about Ranunculaceae : Morphological Diversity Of Families : Dicotyledons CLICK HERE 

To know about Brassicaceae (Cruciferae)/Mustard Family : Morphological Diversity CLICK HERE

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