Gramineae

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Chapter: Pharmacognosy and Phytochemistry : Study of Different Families

A British systematic botanist J. Hutchinson published his work, The Families of Flowering Plants in 1926 on dicotyle-dons and in 1934 on monocotyledons. Hutchinson made it clear that the plants with sepals and petals are more primitive than the plants without petals and sepals on the assumption that free parts are more primitive than fused ones.


GRAMINEAE

 

Habit: These are herbs, rarely woody, as bamboos. They are very widely distributed all over the earth.

 

Stem: This is cylindrical and has distinct nodes and internodes (sometimes hollow), called culm.

 

Leaves: These are simple, alternate and distichous. They have a sheathing leaf base that is split open on the side opposite the leaf blade. There is a hairy structure, called the ligule, at the base of the leaf blade.

 

Inflorescence: This is usually a spike or a panicle of spikelets. Each spikelet consists of one or few flowers (not exceeding five), and its base-bears two empty bracts or glumes (GI, GII), one placed a little above and opposite the other. A third glume, called the lemma or flowering glume, stands opposite the second glume. The lemma encloses a flower in its axil. It may have a bristle-like appendage, long or short, known as the awn. Opposite the flowering glume or lemma, there is a somewhat smaller, two-nerved glume called the palea. The spikelet may be sessile or stalked.

 

Flowers: These are usually bisexual, sometimes unisexual and monoecious.

 

Perianth: This is represented by 2- or 3-minute scales, called the lodicules, at the base of the flower. These are considered to form the rudimentary perianth.

 

Androecium: There are three stamens, or sometimes six, as in rice and bamboo. The anthers are versatile and pendulous.

 

Gynoecium: The carpels are generally considered to number (three), reduced to one by their fusion or by the suppression of two. The ovary is superior and one-celled, with one ovule. The styles usually number two (three in bamboos, and two fused into one in maize, rarely one). They may be terminal or lateral. The stigmas are feathery.

 

Fruit: The fruit is a caryopsis.

 

Seed: This is albuminous. Pollination by the wind is most common. Self-pollination occurs in a few cases, as in wheat.

 

Floral Formula: HP Lodicules2 or 3 A3 or 6 G(3) or 1

 


      Floral diagram of gramineae 


Examples: Rice, maize, bamboo, etc.

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