Anatomy and functions of different parts of flowering plants

Introduction

Anatomy is the branch of biology which deals with the study of internal structure of a living being. Plant anatomy is the study of a plant’s interior structure. Cells are the basic structural and functional unit of living organisms. Cells are organised into tissues, then the tissues get organised into organs. The anatomy of different organs in a plant is different. Monocots and dicots are considered to be morphologically distinct within angiosperms (flowering plants). Internal structures are also adaptable to a variety of settings.

Structure of an Angiospermic Plant

A typical angiosperm has two main parts-

• The root system
• The shoot system 

The root system It is the underground part of the plant which helps in fixation of the plant to its substratum. It helps in the absorption of water and minerals. Roots arise from the seed radicle.

The root system is of two types in angiosperms-

• Fibrous root system
• Tap root system

Fibrous root system consists of numerous thin root fibres which arise from the base of the stem.Such roots are found in monocots.

Tap root system comprises primary root, secondary root, tertiary root and root fibers. This type of root system is found in dicots.

Adventitious Roots– These are the roots that arise from different parts of the plant but not from the seed radicle. These roots are found in monocots as well as dicots and can perform diverse functions like mechanical support to the plant or storage of food. Examples are hanging roots of banyan trees.

The shoot system

This system is found above the ground and consists of stem, branches, leaves, flowers and fruits. Seed plumule gives rise to the shoot system.

• Stem: Stems are primarily responsible for supporting and elevating leaves, fruits, and flowers. 

Classification of different types of stems

• Aerial stem
• Subaerial stems
• Underground stems

 Types of Stem

• Aerial stems– These are a type of stem that grows in the air and is phototropic. These stems can be found above ground and serve a variety of purposes.

Aerials come in a variety of shapes and sizes when modified:

• Thorns– These plant-protecting stem changes show as hard, woody, and pointy outgrowths. Roses, for example
• Tendril stems– are slender, twining strands that allow a plant to climb on other surfaces while seeking support
• Subaerial stems– These run parallel to the ground and produce roots at intervals called nodes.These are weak so cannot stand erect thus creep on ground. Few type of subaerial stems are given below-

• Runner – It has a creeping stem with long internodes and grows parallel to the ground. The nodes on the lower surface produce adventitious roots at regular intervals. A runner emerges from the axils of the aerial stem’s lower leaves e.g. doob grass
• Offset-It is shorter and thicker than runners and are frequently found in water plants e.g. water hyacinth

1. Underground stems– These stems stay close to the ground and develop aerial shoots that ascend above them. Their roots are visible on the surface. Food storage and perennation are the functions of these stems. These stems can also be propagated vegetatively. They are of different types:

2.   Leaf- The kitchen of the plant is referred to as a leaf. They are the primarily responsible for photosynthesis, which is how the plant obtains its energy or food. The leaf structure includes the petiole and lamina.

3.   Flowers- As beautiful as they are for our eyes, flowers are essential for the reproduction of plants. The various floral parts are peduncles, receptacles, sepals,petals, stamens and pistils.

4.   Fruit and seeds- The ovary part of pistil converts into fruit on fertilization and the ovules inside the ovary turn into seeds. In monocots the seeds have only one cotyledon along with endosperm and embryonic shoot. In dicots the seed consists of the two cotyledons, embryonic axis and seed coat 

Anatomy of stem

Nodes and internodes divide the stem. The nodes produce leaves and contain the buds that develop into branches. Internodes separate two nodes. It has three fundamental types of tissues on the inside: 

• Dermal tissue
• Ground tissue
• Vascular tissue

 Dermal tissue, ground tissue and vascular tissue are the three tissues that make up a stem as well as are present in other parts of the plant also. The dermal tissue covers the stem’s exterior surface and serves to waterproof, protect, and regulate gas exchange.

The ground tissue, which fills in around the vascular tissue, is mostly of parenchyma cells. It plays a role in photosynthesis on occasion if chloroplasts are found inside their cytoplasm.

Vascular tissue helps in long-distance transport of water, minerals and food and also provides structural support. Example xylem and phloem.

Plant Tissues– A plant tissue system is a functional unit that connects all of a plant’s organs. These are divided into meristematic tissues and permanent tissues each with its own set of features and functions.

• Meristematic tissue- It is made up of a collection of cells that can divide throughout their life. These tissues are cuboidal in shape and densely packed. As they age, these tissues can extend, expand, and differentiate into distinct types of tissues. Example cambium and cork cambium

• Permanent tissues– It loses its ability to divide immediately after the formation. This tissue is formed from meristematic tissues. They are further divided into two categories:

 (a) Simple Permanent tissues- Composed of similar types of cells.

 (b) Complex Permanent tissues – Composed of different types of cells. 

Conclusion

Plant anatomy is a branch of biology that bridges morphology and cell biology. Plant anatomy allows students to conceptualise the relationship between organismal structure and function. It also aids in the discovery of connections between form, function, taxonomy, ecology, and developmental genetics.