Floral Formula of Fabaceae (The Pea Family)

Fabaceae, commonly known as the legume or pea family, is the third largest and economically important plant family with 630 genera and 18000 species. It is cosmopolitan in distribution. It is distributed all over the world. This family encompasses a diverse group of plants, including trees, shrubs, and herbaceous plants.

1.0Systematic Position of Fabaceae

2.0Symbols : Floral Formula Of Fabaceae

3.0Fabaceae Floral Diagram and Formula

Floral formula

Bracteate, sometimes bracteolate (Sesbania) , complete, zygomorphic,bisexual,, pedicellate, perigynous, pentamerous and papilionaceous (Butterfly condition). 

4.0Characteristics Features Of The Family Fabaceae

This family was earlier called Papilionoideae, a subfamily of family Leguminosae. It is distributed all over the world.

Habit : Primarily herbs, but variations include shrubs and trees some exhibit climbing nature.

Phaseolus vulgaris, the common bean with flower and fruits

 Broad bean, (Vicia faba) with flower and fruits

Pea, (Pisum sativum) with flower and fruits

Peanut, (Arachis hypogaea) with Flower and fruits

Root : Lateral roots commonly have nodules, these nodules are the characteristic feature of this family housing nitrogen-fixing bacteria (Rhizobium). These nodules are the characteristic feature of this family. These bacteria convert atmospheric nitrogen into nitrogenous material.

Stem : Herbaceous, woody, or climbers with tendrils. Tendrils are wiry, coiled, and thread-like structures aiding in climbing.

Leaves : Mostly alternate and stipulate. Simple or Pinnately compound, Stipules are mostly leafy; leaves may be modified into tendrils. Leaf base is swollen and known as Pulvinous. Reticulate venation present. 

Inflorescence : mostly racemose types.

Flowers : Bracteate, occasionally bracteolate (e.g., Sesbania), complete, and bisexual. Zygomorphic, pedicellate, perigynous, pentamerous, and papilionaceous.

Calyx : Typically 5 sepals, often united to form a hairy tube. Valvate or imbricate aestivation. 

Corolla : Comprises five unequal, papilionaceous petals with bilateral symmetry. Standard or Vexillum (largest), Wings (lateral), and Keel or Carina (boat-shaped).

Aestivation is descending imbricate. 

Androecium : Stamens10,diadelphous, usually 9+1 (Clitoria ternatea). The odd stamen is posterior in position. 

In Aeschynomene aspera, the stamens are fused to form two bundles each containing five stamens (5)+5. Stamens are monadelphous and dimorphic ie. 5 stamens have longer filaments and other 5 stamens have shorter filaments thus the stamens are found at two levels and the shape of anthers also varies in (Crotalaria verrucosa). (5 anthers are long and lanceolate, and the other 5 anthers are short and blunt). Anthers are dithecous, basifixed and dehiscing longitudinally.

Gynoecium : Simple pistil with a single carpel (monocarpellary), single locule, and superior ovary. Numerous ovules on the ventral suture with marginal placentation.

Fruit : Usually a legume or pod, dehiscing by one or both sutures into two valves, non-endospermic.

Pollination :Entomophilous pollination(By insects). 

5.0Economic Importance Of The Family Fabaceae 

This plant family holds significant economic value, contributing to various sectors such as food production, fodder, fatty oils, fibers, timber, dyes, gums, and ornamentals.

Butea monosperma (the flame of the forest. Palash is also known as Tesu.)

Pulses: Major pulses essential for human consumption belong to this family, known for their protein-rich content. 

Notable pulse species include Pisum sativum (Pea; Matar), Cicer arietinum (Gram; Chickpea), Glycine max (Soybean), Cajanus cajan (Pigeon pea; Arhar), Lens culinaris (Lentil; Masur), Vigna radiata (Green gram; Moong), Vigna mungo (Black gram; Urd), etc.

Vegetables: Vigna unguiculata (Cowpea; Lobia) and Phaseolus vulgaris (Kidney bean, French bean, etc.) are essential vegetables derived from this family.

Fodders: Medicago sativa (Alfalfa) stands out as one of the premier forage crops. Various clover species (Trifolium) are also cultivated as primary fodder crops.

Timber: Some members of this family are a valuable source of timber for construction, furniture, and fuel. Dalbergia sisso (Shisham)

Vegetable Oil : Arachis hypogea (Peanut) seeds, in addition to being edible, are utilized for extracting peanut oil. This oil undergoes hydrogenation and serves as a commonly used vegetable oil. Soybean oil is another important oil obtained from Glycine max.

Dyes: Indigofera tinctoria (Indigo) and its variations are sources of indigo dye.

Indigofera tinctoria (Indigo)

Medicinal Plants : Glycyrrhiza glabra (Licorice) is employed for treating coughs and colds. 

Ornamental Plants: Certain members of this family serve ornamental purposes, including Lathyrus odoratus (sweet pea), Lupinus albus (lupin) and Desmodium gyrans (indian telegraph plant) etc. 

Lathyrus odoratus (sweet pea)

Mimosa pudica (Sensitive Plant Touch Me Not or Shy Plant )

6.0Multiple Choice Questions(MCQs/NEET)

Q.1 Vexillum is the other name for

(1) Wing petal (2) Keel petal

(3) Standard petal (4) ligulate

Ans. (3) Standard petal

Q.2 Roots with root nodules are found in 

(1) Fabaceae (2) Solanaceae (3) Liliaceae (4) Brassicaceae

Ans. (1) Fabaceae

Q.3 Botanical name of Gram is

(1) Phaseolus aureus (2) Phaseolus mungo

(3) Cicer arietinum (4) Cajanus cajan

Ans. (3) Cicer arietinum

Q.4 Largest petal of papilionacEous corolla is called

(1) Standard (2) Vexillum (3) Ala (4) Both (1) and (2)

Ans. (4) Both (1) and (2)

Q.5 Petals from a boat shaped structure in papilionaceous corolla-

(1) One, anterior (2) One, posterior

(3) Two, anterior (4) Two lateral

Ans. (3) Two, anterior

Q.6 What is the true of androecium of fabaceae ?

(1) Ten free (2) 10 monoadelphous

(3) 10 diadelphous (4) 10 polyadelphous

Ans. (3) 10 diadelphous

Q.7 Gynoecioum of fabaceae is -

(1) Bicarpellary syncarpous (2) Polycarpellary apocarpous

(3) Polycarpellary syncarpous (4) Monocarpellary

Ans. (4) Monocarpellary

Q.7 Which of the following are not characteristic features of Fabaceae?

(1) Flowers actinomorphic, twisted aestivation and gamopetalous

(2) Stamens ten, introrse, basifixed and dithecous

(3) Tap root system, compound leaves and raceme inflorescence

(4) Monocarpellary, ovary superior and bent stigma

Ans. (1) Flowers actinomorphic, twisted aestivation and gamopetalous