The family is commonly known as grass family. It is one of the largest among the angiospermic families. It consists of 620 genera and 6,000 species. The members are cosmopolitan in distribution. The plants represent all the 3 ecological types i.e. hydrophytes, xerophytes and mesophytes. In India it is represented by 850 species.
Habit:
Herbs, annuals or perennials, or shrubs, sometimes tree like (Bambusa, Dendrocalamus)
Roots:
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Adventitious, fibrous, branched, fascid or stilt (Zea mays).
Stem:
Underground rhizome in all perennial grasses, cylindrical, culm with conspicuous nodes and internodes, internodes hollow, herbaceous or woody, glabrous or glaucous, vegetative shoots arising from the base of aerial stem or from underground stems are called tillers.
Leaves:
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Alternate, simple, distichous, exstipulate, sessile, ligulate (ligules the portion of leaf sheath which projects above the attachment of lamina) (absent in Bambusa), leaf base forming tubular sheath, sheath open, surrounding internode incompletely, ligule is present at the junction of the lamina and sheath, entire, hairy or rough, linear, parallel venation.
Inflorescence:
Compound spike which may be sessile or stalked. Each unit of inflorescence is spiklet. The spiklets are arranged in various ways on the main axis. A compound inflorescence may be spike of spikelets (Triticum), panicle of spikelets (Avena).
The spikelet consists of a short axis called Rachilla, on which one to five sessile or short stalked flowers are borne. The florets may be arranged in alternate or opposite manner on the central axis.
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At the base of the rachilla two sterile scale, called glumes, are present. The glumes are placed one above the other on the opposite side. The lower one is called first glume and the upper one is called second glume.
Both the glumes are boat shaped and sterile. Above the glumes a series of florets are present. Each floret has an inferior palea or lemma and above it a superior palea. The lemma frequently bears a long stiff hair called awn.
Flower:
Bracteate and bracteolate, sessile, incomplete, hermaphrodite or unisexual (Zea mays) irregular, zygomorphic, hypogynous, cyclic.
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Perianth:
Represented by membranous scales called lodicules. The lodicules are situated above and opposite the superior palea or may be absent or many (Ochlandra) or 2 or 3.
Androecium:
Usually stamens 3, rarely 6 (Oryza, Bambusa) and one in Cinna and various species of Fistuca. Filaments long, anthers dithecous, versatile, linear, extrose. Pollen grains dry.
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Gynoecium:
Monocarpellary, according to some authors, carpels 3 of which 2 are abortive, ovary superior, unilocular with single ovule, basal placentation, style short or absent, stigma two.
Fruit:
Caryopsis, a pericarp compeletely united or adherent with the seed coat, or rarely nut (Dendrocalamus) or berry (Bambusa).
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Seed:
Endospermic and containing a single cotyledon called scutellum, which in shield shaped and pressed against the endosperm.
Cereals:
(1) Triticum aestivum (Wheat)
(2) Zea mays (Maize)
(3) Oryza sativa (Rice)
(4) Avena sativa (Oat, jai)
(5) Hordeum vulgare (Barley =jau)
Millets:
(1) Sorghum vulgare (Jawar = Great millet)
(2) Pennisetum typhoides (Bajra)
Sugar plant:
(1) Saccharum ojficinarum (Sugarcane)
Grass:
(1) Cynodon dactylon (Doob grass)
(2) Andropogon muricatus (Khas, oil extracted from root)
Paper grass:
(1) Themeda gigantia (Kuproon grass)
(2) Eucaliopsis binata (Bhabar grass) Other use :
(1) Bambusa species: Bamboo of commerce used for making poles, chairs, baskets, tables etc.
(2) Dendrocalumus species
(3) Sachharum munja (Munj)
The fibre called munj is used for making ropes.
Division – Angiospermae
Class – Monocotyledonae
Series – Glumaceae
Family – Gramineae (Poaceae).