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Semi Technical Description of Fabaceae: Vegetative and Floral Characters, Description of Fruits and Seeds, Floral formula and Floral Diagram, Economic Importance, Practice Problems and FAQs
You might have heard about the famous experiment by Johann Mendel. Yes, he is the father of Genetics. He performed lots of experiments on a particular plant. Let’s do an activity now. Try to find out the name of the fabulous plant on which Mendel did his research work.
Yes, you are right. It is the garden pea plant or Pisum sativum.
Fig: Pea flower
But do you have any idea about the plant family in which the pea plant belongs? Who are the other members of this particular plant family? What are the main characteristics of this particular plant family? The pea plant is an example of the family Fabaceae. It is the third largest family of angiosperms. It is also known as legume or bean family which is distributed all over the world. So let’s understand the qualities of the members of this family in detail in this article.
Table of contents
- Family Fabaceae - The pea family
- Vegetative characters
- Floral characters
- Description of fruits and seeds
- Floral formula of family Fabaceae
- Floral diagram of family Fabaceae
- Economic importance
- Practice Problems
- FAQs
Family Fabaceae - The pea family
Earlier this family was called Papilionoideae, a subfamily of the family Leguminosae. It is distributed all over the world. It belongs to the division Spermatophyta, sub-division Angiospermae, class Dicotyledonae and order Rosales.
Vegetative Characters
Habitat
It is a terrestrial plant with an erect stem or a climber.
Habit
It is of four types as follows:
Herbs |
Shrubs |
Trees |
Climbers |
|
Fig: Licorice (Mulethi) |
Fig: Bush clover |
Fig: Caesalpinia |
Fig: Pea plant |
Description of the root and shoot system
The following are the major characteristics of root system and shoot system in family Fabaceae:
Root System |
Shoot System |
| Tap root system |
Stems are either erect or weak. Weak stems climb using support.
|
|
Fig: Tap root system
|
Fig: Stem |
| Leguminous - Root nodules present |
Leaf
|
|
Fig: Root nodules
|
Fig: Parts of a leaf |
| Nodules have nitrogen fixers such as Rhizobium |
Pulvinate: They possess a swollen leaf base (pulvinus)
Fig: Pulvinus |
|
Shows reticulate venation
Fig: Reticulate venation
|
Floral Characters
The following are the major floral characters of the family Fabaceae.
Inflorescence
Racemose inflorescence with acropetal succession is seen in the Fabaceae family. It shows indefinite growth of the floral axis.
Fig: Inflorescence
Flower
They are the ornaments of the plant. In this family flowers shows vexillary aestivation with three different types of petals as follows:
Standard petal or banner
It is the outermost and largest petal of the flower.
Wing or alae
These are characterised as two lateral petals.
Keels or carinae
These are the two innermost and smallest petals in a flower.
Fig: Types of petals in flower
Sexuality
Flower is bisexual or hermaphrodite (⚥).
Fig: Bisexual flower
Symmetry
Flower is zygomorphic hence shows bilateral symmetry (%).
Fig: Bilateral symmetry
Description of calyx and corolla
The following are the major characteristics of calyx and corolla:
Calyx (K) |
Corolla (C) |
|
Pentamerous: Possess 5 sepals - K5 Gamosepalous: Fused sepals - K(5) Fig: Gamosepalous |
Pentamerous: 5 petals - C5 Polypetalous: Free petals - C5
Fig: Pentamerous |
|
Exhibit either valvate or imbricate aestivation
Fig: Valvate
Fig: Imbricate |
Vexillary aestivation or papilionaceous corolla present
Fig: Papilionaceous corolla |
Description of androecium and gynoecium
The following are the major characteristics of androecium and gynoecium:
Androecium (A) |
Gynoecium (G) |
|
10 stamens present in diadelphous arrangement A(9)+1
Fig: Diadelphous arrangement |
Monocarpellary - Single carpel
Fig: Monocarpellary ovary |
|
Each stamen has a dithecous anther with two lobes
Fig: Dithecous anther |
Multiple ovules in an ovary
Fig: Multiple Ovules |
|
Unilocular ovary
Fig: Locules of the Ovary |
|
|
They show marginal placentation
Fig: Marginal placentation |
Description of fruits and seeds
The following are the major characteristics of fruits and seeds:
Fruit |
Seed |
|
The ovary transforms into fruit and ovules into seeds after fertilisation. The plants of this family produce a characteristic legume fruit. Hence, these are also known as leguminous plants. The legume fruit develops from a monocarpellary unilocular ovary. The fruit dehisces and liberates seeds at maturity.
|
Dicotyledonous seeds are present in this family. They have two cotyledons and their seeds lack endosperm. Hence called non endospermous seeds.
|
|
Fig: Fruits |
Fig: Structure of dicotyledonous seed |
Parts of seed
The seed of the Fabaceae family is dicotyledonous and non endospermous. It possesses seed coats. Outer seed coat is called testa and the inner membranous seed coat is called tegmen. Two cotyledons are present. Embryo has an embryonal axis which possess a plumule or shoot tip and radicle or root tip. The region below the attachment of cotyledon is called hypocotyl and above the attachment of cotyledon is called epicotyl.
Fig: Pisum sativum
Floral formula of Fabaceae
The details of the floral formula in the Fabaceae family is given below:
Fig: Floral formula
Floral diagram of family Fabaceae
The outermost whorl depicts the calyx. It has five sepals. The aestivation present here is valvate. The second whorl is corolla. It has vexillary aestivation. The third whorl called androecium has 10 stamens with diadelphous conditions. The innermost or fourth whorl is gynoecium. It has a single carpel. Marginal placentation can be seen here.
Fig: Floral diagram
Economic Importance
Fabaceae includes plants that produce pulses, which are rich sources of proteins. Examples include chickpea, gram or Bengal gram, moong (green gram), Indian beans (sem), red gram or arhar. This family also includes plants producing edible cooking oils like soybean and groundnut. Sesbania and Trifolium are useful as fodder for animals. Dye fabrication is done with a natural blue dye obtained from the Indigofera plant. Lupin and sweet peas are useful as ornaments. Mulethi or licorice has useful medicinal properties.
Practice Problems
1. Which phenomenon occurs when the filaments of all the stamens of a flower are fused together to create a single bundle?
a. monandrous
b. monadelphous
c. diadelphous
d. polyadelphous
Solution: The filaments of all the stamens in Hibiscus rosa-sinensis (China rose) are fused together to create a single bundle termed the staminal column. This is referred to as a monadelphous condition. Hence, the correct option is b.
2. Which of the following families used to be known as Papilionoideae?
a. Fabaceae
b. Asteraceae
c. Solanaceae
d. Liliaceae
Solution: Papilionoideae was the previous name for the Fabaceae family. The presence of a papilionaceous corolla earned the family the name Papilionoideae. Five petals make up the papilionaceous corolla. One huge standard petal that spans the two lateral wing petals and is totally outside. The two little keel petals are then overlapped by these. The keel petals are joined and envelop the flower's reproductive components. Due to the genus ‘Faba’ the Papilionoideae family has been renamed Fabaceae. Hence, the correct option is a.
3. The pea plant's fruit is known as ______________.
a. Capsule
b. Berry
c. Legume
d. Drupe
Solution: Pea fruit is classified as a legume. Legume, often known as a pod, grows from a monocarpellary unilocular ovary and dehisces dorsoventrally to release seeds when mature. It is a typical fruit of the Fabaceae family. Hence, the correct option is c.
4. Plants belonging to which family have nodules on their roots?
a. Fabaceae
b. Solanaceae
c. Liliaceae
d. Asteraceae
Solution: Nodules can be seen on the roots of plants belonging to the Fabaceae family. These root nodules contain nitrogen-fixing symbiotic bacteria (Rhizobium), which aids in nitrogen fixation from the atmosphere. Hence, the correct option is a.
FAQs
Q 1. How many plants are there in the Fabaceae family?
Answer: Fabaceae family is commonly known as a pea family. There are around 670 genera and nearly 20,000 species of trees, shrubs, vines, and plants in the Fabaceae family.
Q 2. Why is the Fabaceae family known as a protein-rich family?
Answer: Fabaceae family is known as protein-rich because it is the main source of pulses like gram, moong, and soya bean which are rich in protein.
Q 3. How are plants of the Fabaceae family used?
Answer: The plants of the Fabaceae family are widely used in the pharmaceutical, cosmetics, food, and textile industries.
Q 4. Name the largest plant of the Fabaceae family.
Answer: The largest plant is Entada gigas, which reach up to 2 metres in length.
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