Sub-family Papilionaceae :
Class — Dicotyledones
Sub-class — Polypetalae
Series — Calyciflorae
Order — Rosales
Family — Leguminosae
Sub-family — Papilionaceae
Distribution :
This sub-family includes 490 genera and 12000 species which are cosmopolitan in distribution but mostly present in tropical and subtropical areas.
In India the sub-family is represented by 100 genera and 750 species.
Arachis hypogaea (Peanut), Cicer arietinum (Gram), Dalbergia sissoo (Shisham), Pisum sativum (Garden pea), Glycine max (Soyabean) and Trigonella foenum- graceum (Fenugreek) are some familiar examples of this sub-family.
Vegetative Characters :
1. Habit
There are mostly herbs (e.g., Melilotus, Cajctnus cajan. Medicago, Trigonella, Crotalaria).
Climbers: Plants which move up by tendril are called as climbers (e.g., Lathyrus, Pisum)
Twiners: Plants which moves up by twisting around- some support (e.g., Clitoria, Dolichos, Phaseolus).
Shrubs: few are shrubs (e.g., Cajanus cajcm (Arhar), Crotalaria juncea, Butea)
Trees: Dalbergia. Erythrina.
Xerophytes: A Ihctgi pseudoalhagi.
2. Roots
Tap root, roots have nodules in which Nitrogen fixing bacteria Rhizobium lives as Symbiotic association to convert atmospheric nitrogen into nitrite or nitrate to increase fertility of soil so these roots are also called as nodulated roots.
3. Stem
Stem is herbaceous or woody; sometimes weak, tendril or leaf climber.
It is erect, creeping, branched, cylindrical and angular.
4. Leaves
Leaves are alternate and stipulate.
The leaf base is swollen that called pulvinus.
Reticulate venation.
In Medicago, Trifolium stipules are adnate.
In Cajanus and Sesbania stipules are free-lateral.
In Desmodium gyrans (Indian Telegraph plant) two lateral leaflets of trifoliate leaf regularly moves up and down at 180° angle by autonomous movement of variation.
In Pisum and Lathyrus odoratus upper leaflets get modified into tendrils while in Lathyrus aphaca (Wild pea) complete leaf get modified into tendril.
They are simple (e.g., Alysicarpus), palmately compound (e.g., Melilotus. Trifolium) or pinnately compound (e.g., Sesbania, Dalbergia, Lathyrus)
Floral Characters :
1. Inflorescence
Racemose type of inflorescence.
Racemose raceme in e.g., Pisum, Melilotus alba
Spike in Uraria
Axillary Head in Trifolium
Solitary axillary in Lathyrus, Cicer arietimim
Racemose of cymes in Tephrosia.
Panicled raceme in Dalbergia
2. Flowers
Flowers are bracteate, bracteolate, pedicellate, complete, cyclic, bisexual, zygomorphic pentamerous.
They are usually hypogynous or slightly perigynous.
3. Calyx
Calyx is made of 5 sepals which are united (gamosepalous)
Odd sepal is anterior.
The aestivation is valvate or imbricate.
4. Corolla
Corolla consists of 5 petals.
They are polypetalous and characteristically papilionaceous. Aestivation is Vexillary or descending imbricate.
The odd posterior petal called standard or vexillum, is the largest. The two lateral ones, called wings, are relatively smaller, and the two anterior ones, called keel or carina, are united to form a boat-shaped structure.
In Lespedeza corolla absent.
5. Androecium
Androecium consists of 10 stamens.
They are usually diadelphous, 1+ (9) e.g, Peanut (Arachis hypogea). Shisham (Dalbergia sissoo).
Sometimes all the stamens are united in a single group, i.e., monadelphous (e.g., Crotalaria, Pongamia).
Rarely, the stamens are polyandrous (e.g., Sophora).
Anthers are dithecous, dorsifixed and introrse.
6. Gynoecium
Gynoecium is monocarpellary.
The ovary is superior, unilocular and has many ovules on ventral sutures. In Lespedeza the ovary has only a single ovule..
Plantation is marginal.
The style is simple, single and long. Stigma is capitates. In Pisum stigma is sword shape.
7. Floral Formula
8. Fruit
Fruit is a legume (pod) or a lomentum.
In Arachis hypogaea (ground nut) the lomentum is geocarpic. i.e., it develops underground.
In Dalbergia the fruit is indehiscent and winged; the wings developing from the fruit wall.
9. Seed
The seeds are exalbuminous or non-endospermic.
Floral structure and floral diagram of family Fabaceae (Lathyrus odoratus)
10. Distinguish characters of Papilionaceae
Flower is zygomorphic.
Aestivation is descending imbricate or vexillary.
Corolla is Papilionaceous.
Stamens diadelphous
Root nodules with Rhizobium bacteria in roots.
Economic Importance :
Economically, Papilionaceae is one of the most important families of angiosperms.
All pulses belong to this family.
Pulses are rich in proteins. Besides pulses, the family also provides vegetables, oils, food, medicines and timber.
