The below mentioned article provides a short note on Diversity in Plant Body. After reading this article you will learn about: 1. Introduction to Plant Body 2. Fundamental Parts of the Plant Body.
Introduction to Plant Body:
The plant body of an angiosperm consists of a number of organs, i.e., roots, stem, leaf and flower. The flower consists of sepals, petals, stamens, carpels and sometimes also sterile members. Each organ is made up of a number of tissues. Each tissue consists of many cells of one kind.
A vascular plant begins its existence as a morphologically simple unicellular zygote (2n). The zygote develops into the embryo and thereafter into the mature sporophyte. The development of the complex multicellular body of the seed plant is a result of evolutionary specialization of long duration.
The specialization has given rise to the establishment of morphological and physiological differences between the various parts of the plant body and also caused the development of the concept of plant organs.
As regards the morphologic nature of the flower it is thought that the flower is homologous with a shoot and the floral parts with leaves.
Fundamental Parts of the Plant Body:
The axis, consists of two parts that portion which is normally aerial is known as the stem, and that portion which is subterranean is called the root.
There are three types of appendages arising from the axis:
1. Leaves:
The strands of vascular tissue pass through the leaves. The leaves are characteristic of the stem and do not occur on the root. The leaves are found to be arranged on the stem in a definite manner, and bear an intimate structural relation to the skeleton of the axis.
The leaf is looked upon as the lateral expansion of the stem, continuous with it. All fundamental parts of the stem are concerned with the formation of the leaf.
2. Emergences:
In the appendages of the second rank only the outermost layers of stem, the cortex and the epidermis, are usually present which are known as emergences. The prickles of the rose make a good example of it.
3. Hairs:
The appendages of the third rank are hairs. These are projections of the outermost layer of the cells. The emergences and hairs occur on both axis and leaves, usually without definite arrangement.