Plant Morphology

FRUIT

sturcutre of fruit

Fruit is a mature, ripened ovary which develops after fertilization. If a fruit develops without fertilization, it is called parthenocarpic fruit.

A fruit usually consists of a wall and seeds. The wall of the fruit is called pericarp. The pericarp can be dry or fleshy. A fleshy pericarp is differentiated into three layers, viz. epicarp, mesocarp and endocarp.


SEED

Ovules develop into seeds after fertilization. A seed is composed of a seed coat and an embryo. The embryo is composed of a radicle, an embryonal axis and one or two cotyledons.

Structure of a Dicotyledonous Seed

sturcutre of dicotyledonous seed

The outermost covering of the seed is called seed coat. The seed coat is composed of two layers. The outer layer is called testa and the inner layer is called tegmen.

There is a scar on the seed coat through which the developing seed was attached to the fruit. This scar is called hilum. There is a small pore above the hilum; called micropyle.

The embryo lies within the seed coat. It is composed of an embryonal axis and two cotyledons. Cotyledons are usually fleshy and contain reserve food materials.

Radicle and plumule are present at the two ends of the embryonal axis.

Endosperm is present in some seeds. Such seeds are called endospermous. When endosperm is not present in mature seeds, the seeds are called non-endospermous.


Structure of Monocotyledonous Seed

sturcutre of monocotyledonous seed

Monocotyledonous seeds are usually endospermic, but some are non-endospermic, e.g. orchids.

In the seeds of cereals, the seed coat is membranous and is usually fused with the fruit wall.

The endosperm is bulky and stores food. The outer covering of endosperm separates the embryo by a proteinous layer. This layer is called aleurone layer.

The embryo of monocot seed is small. It is situated at one end of the endosperm. It consists of one large and shield-shaped cotyledon which is known as acutellum. There is a short embryonal axis; with radicle and plumule.

The plumule and radicle are enclosed in sheaths which are respectively called coleoptiles and coleorrhiza.


SEMI-TECHNICAL DESCRIPTION OF A TYPICAL FLOWERING PLANT

The semi-technical description of a typical flowering plant should be brief. It should be written in simple and scientific language. It should be in proper sequence. The description begins with habit, vegetative characters and then floral characters, inflorescence and floral parts.

Floral Formula: This is a short description of a particular flowering plant which shows key characters through various symbols. Various symbols used in floral formula are; Br(for bracteates), K (for calyx), C (for corolla), P (for perianth), A (for androecium) and G(for gynoecium). G is used for superior ovary and G (with a line above it) is used for inferior ovary, ♂ is used for male flower, ♀ is used for female flower, ⚥ is used for bisexual flower, ⊕ is used for actinomorphic flower and % is used for zygomorphic flower.

Fusion of floral part is indicated by enclosing the figure within bracket. Adhesion of floral parts is indicated by drawing a line above the symbols of the floral parts. A floral diagram gives the information about the number of different parts of a flower, their arrangement and their relation with one another. The position of the mother axis is shown by a dot on top of the floral diagram. Different whorls of the flower are drawn in correct sequence.



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