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Plant Biology

Introduction

A plant is a living organism and is immobile. Plant is having autotrophic mode of nutrition and divided into two types – Cryptogams and Phanerogams. Cryptogams do not have flowers or seeds where as Phanerogams possess flowers and seeds during their lifetime. A plant can be studied by its internal constitution and by its external characters. A typical flowering plant has a main unbranched or branched axis. The main axis is divided into tow parts – an underground toot part and an above ground shoot part.

The axis of a plant which contains flowers is called rachis. The pattern of arrangement of flowers on the rachis is called Inflorescence. A flower is a part of shoot morphology. A shoot is modified for the special function of sexual reproduction, which is called a flower. A flower is further classified as complete flower or incomplete flower and bisexual or unisexual flower. A flower contains calyx, corolla, androecia and gynoecia.

A fertilized and ripened ovary is called fruit. The wall of ripened ovary is called pericarp and fertilized ovule is called a seed. Fruits are two types – true fruit develop only from and ovary and false fruit develops from an ovary, the thalamus and other part of flowers. Fruits are further classified based on their origin and developments are – simple fruit, aggregate fruit and composite fruit.

After fertilization, the ovule in the ovary is converted into seeds. A seed contains cotyledons, plumule, and radical. A seed exhibits many variations in their shapes, sizes, viability and germination.

Internally plant is made up of cells. These cells aggregate and forms tissues. Various tissues organize together to form tissue system and then organs. Plant tissues are divided into two groups – Meristematic and permanent tissue. A tissue system in plant is also divided into three types – Epidermal, ground and conducting tissue system.

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