POACEAE

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            1. SYSTEMATIC POSITION:
            Bentham & Hooker
            Division: Phanerogames (Seed Plants)
                 Class: Monocotyledones
                        Series: Glumaceae
                               Family: Poaceae
           
            2. MORPHOLOGICAL CHARACTERS:
            Habit – Usually annual or perennial herbs.
            Stem – Clums erect, ascending, creeping, terete, internode hollow, nodes swollen, creeping rhizome or stolon present.
            Leaves – Simple, alternate, often crowded at the base, consisting of sheath, blade and ligule, blade usually long, narrow and entire.
            Inflorescence – Spikelets, these are very small spikes with one or more flowers arranged in spike, raceme or panicle, flowers stalked or sessile. Each spikelet bears at its base two minute scales or bracts called empty glumes. Slightly above, it bears a third bract called flowering glume or lemna. Opposite to the lemna/ flowering glume a small 2-nerved bracteole called palea is present.
            Flower – Florets small, inconspicuous, bisexual or unisexual, zygomorphic, hypogynous.
            Perianth – 2 or rarely 3 or 0, represented by minute membranous scales called lodicules.
            Androecium – Generally 3, sometimes 6 or reduced to 2 or 1, filaments long, anther versatile, dithecous, basifixed introrse, dehisce by a longitudinal slit.
            Gynoecium – Bi or tricarpellary, syncarpous, ovary superior, unilocular with ovuls, placentation axile, styles 1-3, commonly 2, short, stigma usually 2, feathery, arise from the carpellary wall. In Zea mays, the style is long and silky, placentation basal.
            Fruit – Caryopsis.
              4. COMPARATIVE SYSTEMATIC POSITION AND AFFINITIES:
            Bentham & Hooker have placed the family Poaceae along with the Cyperaceae in the series Glumaceae. Engler & Prantl placed both the families in their order Glumiflorae, while Cronquist placed them in his order Cyperales. Hutchinson and Takhtajan placed the family in an order of its own which they named as Graminales (for Cyperaceae) and Poales (for Poaceae) respectively.
            The Poaceae are one of the most successful families of the flowering plants with reduced flowers adapted for wind pollination. They are considered to be very advanced group of angiosperms and evolved from primitive liliaceous ancestral stocks.
            Superficially, Poaceae is considered to be resembled with Cyperaceae. In both these families, the flowers are small, inconspicuous, subtended by bracts and present in the form of spikelets. However, Poaceae differs from Cyperaceae by their usually terete, hollow, joined stems, structure of spikelet, etc.
            Hutchinson suggested that the grasses developed parallel with the Sedges from liliaceous stocks through the Juncaceae complex.
                5. ECONOMIC IMPORTANCE:
            The family is economically important in various respects like food value, fodder, making sugar, medicinal, aromatic and manufacture of paper, mats baskets, etc.
            1. The important cereal plants are – Triticum aestivum, T. sativum, T. vulgare, Zea mays, Oryza sativa, Avena sativa, Hordeum vulgare, Sorghum vulgare, Andropogon sorghum, Panicum miliaceum, Pennisetum typhoides, etc.
            2. The fodder plants of the family include – Cynodon dactylon, Bothriochloa pertusus, Panicum maximum, Paspalum spp., Desmostachya bipinnata, etc. The dried stems and leaves of those plants are used as fodder for cattle.
            3. Saccharum officinarum (sugar cane) is used in the manufacture of sugar.
            4. Stems of various species of Bambusa e.g., B. tulda, B. vulgaris, B. polymorpha, Melocanna bambusoides, Dendro-calamus spp., etc are used for building materials and in paper industry. Split stems are used to manufacture raw mats, baskets, tool-handles, etc.
            5. Some plants of the family are aromatic and used as perfumes and oils. Roots of Vetiveria zizanioides yields vetiver oil. Other scented oil yielding plants are the species of Cymbopogon e.g., C. mar-tini, C. nardus, C. citratus, etc.
            6. Medicinal grasses include – Phragmites karka, Secale cereal, etc.

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