The Grass Family. Laboratory Practical

The grass family (about 10 000 species in the textbook, over 11 000 now) consists of annual, biennial and perennial herbs growing on almost all land. The root system is fibrous, made of adventitious roots. The stem is cylindrical, jointed and usually hollow — the culm (straw). Leaves sit in two rows at the nodes; each has a leaf sheath around the stem, a long blade, and at their border a thin membrane, the ligule, that keeps rain water out of the sheath. Flowers are small, colourless or greenish, in spikelets; spikelets are gathered in a spike or panicle. The flower is enclosed in chaff scales, stamens are mostly 3, the pistil is 1 with a feathery branched stigma — an adaptation for wind pollination. The fruit is a dry one-seeded grain. Wheat (Triticum aestivum), rice (Oryza sativa), maize (Zea mays), barley and sorghum are staple food plants. Maize is monoecious: male flowers in the terminal panicle (tassel), female flowers in the cob in a leaf axil. Wild members: bulbous barley, Poa bulbosa (forage for desert pastures), Johnson grass, reed and Bermuda grass; couch grass is a harmful weed with long rhizomes. Two species of the family are in the Red Book of Uzbekistan.