ACP 301- Ariable Crop Production

Habit—herbs, rarely woody, as bamboos. They are very widely distributed all over the earth. Stem cylindrical with distinct nodes and internodes (sometimes hollow), called culm. Leaves are simple, alternate, and distichous, with sheathing leaf-base which is split open on the side opposite to the leaf blade; there is a hairy structure at the base of the leaf-blade, called the ligule. Inflorescence usually a spike or panicle of spikelets (FIG. 74); each spikelet consists of one or few flowers (not exceeding 5), and bears at the base two empty bracts or glumes, (G1; Gu), one placed a little above and opposite the other; a third glume called lemma or flowering glume stands opposite glume II; the lemma encloses a flower in its axil; it may have a bristlelike appendage, long or short, known as the awn; opposite the flowering glume or lemma there is a somewhat smaller, 2-nerved glume called palea. The spikelet may be sessile or stalked. Flowers usually bisexual, sometimes unisexual, monoecious. Perianth represented by 2 or 3 minute scales at the base of the flower, called the lodicules; these are regarded as forming the rudimentary perianth. Androecium— stamens 3, sometimes 6 as in rice and bamboo; anthers versatile and pendulous. Gynoecium—carpels generally considered as (3), reduced to 1 (according to some authors) by their fusion or by suppression of 2; ovary superior, 1-eelled, with 1 ovule; styles usually 2 (but 3 in bamboos, and 2 fused into 1 in maize, rarely 1), terminal or lateral; stigmas feathery. Fruit a caryopsis. Seed albuminous. Pollination by wind is most common; self-pollination in a few cases, as in wheat. Floral formula—