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Maize or Indian corn (Fig. 221) is a stout annual plant cultivated for the grains during the rainy season. It forms a staple food in some parts of India. Roots are of fibrous adventitious type. Primary root aborts after germination, and is replaced by fibrous adventitious ones from the base of stem.
Stems are stout, solid with distinct nodes and internodes. Leaves are simple with entire margin, quite large, linear in shape and arranged alternately. The arrangement is distichous or 2-ranked. They have sheathing leaf-base surrounding a part of internode above.
Membranous ligule is present at the junction of base and blade. Venation is parallel. All the organs have rough surface due to impregnation of silica. Inflorescences are of two types, viz. terminal staminate compound raceme or panicle and axillary pistillate spadix.
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Male inflorescence consists of many spikelets. The spikelets occur in pairs—the lower one is sessile and the upper one is stalked. Each spikelet is two-flowered. They have four glumes.
The first and the second glumes located at the base, are sterile, and the third one, called flowering glume, and the last one, the two-nerved palea, enclose a flower. Flowers are obviously unisexual. Perianth is represented by a pair of fleshy scale-like bodies called lodicules. Androecium is composed of three free stamens with long prominent linear anthers (Fig. 222, 1).
Female inflorescence is a spadix arising from the axil of a lower leaf. A large number of spikelets are arranged closely on the fleshy axis, forming what is known as cob. It remains surrounded by a few large hyaline bracts called spathes.
Each spikelet, like the male ones, is two-flowered and has protective glumes. Of the two, usually the upper flower is fertile and the lower one aborts. Lodicules are absent. Gynoecium is monocarpellary. The ovary is one-chambered, superior, ovoid in shape with a single anatropous ovule. The styles are long and silky. Persistent styles hang out in tufts from the apex of the cob. Stigma is long and feathery (Fig. 222, 2).
Flowers are wind-pollinated. Small dusty pollen grains are easily caught by the feathery stigma of the carpel. Fertilization takes place by normal process. Fruit is a caryopsis with a single closely fitted seed where fruit wall and seed-coat are inseparably united.
A large number of fruits, called grains, remain densely crowded on the spongy axis (Fig. 223). Seeds are albuminous. The single cotyledon, scutellum, serves as the absorbing organ. Germination is hypogeal.
The plant itself is the most prominent generation, the sporophyte, with diploid (2N) chromosomes in the nuclei of the cells, and “the gametophytes with haploid (N) chromosomes are represented by embryo-sac and pollen tube.
They are very small, reduced and dependent on the sporophyte. Gametophytic generation begins with reduction division in microspore-mother cell and megaspore-mother cells with subsequent formation of microspores and megaspores respectively. With fertilization ‘2n’ number it restored and sporophyte begins.
