Distribution of Poaceae:
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 as hydrophytes, xerophytes and mesophytes. In India it is represented by 850 species.
Economic Importance of Poaceae:
The family stands first and foremost in respect of economic importance in whole of Angiosperms. The staple food grains of the population of world is derived from Oryza sativa (Rice) and Triticum aestivum (Wheat). They are cultivated from time immemorial.
The family has been divided on economic basis as follows:
Triticum aestivum, Oryza sativa, Zea mays (Maize), Hordeum vulgare (Jaw), Sorghum vulgare (Jowar), Avena sativa (Oats), Pennisetum typhoides (Bajra) are cultivated for cereals and food grains.
Many grasses as Cynodon dactylon, Panicum, Cymbopogon, Agrostis, Poa are grown for fodder.
Saccharum officinarum (Sugarcane; H. Ganna) is cultivated for gur and sugar.
Some species of Bambusa e.g. B. tulda, B. vulgaris are used for scaffolding, thatching huts etc.
Species of Dendrocalamus (H. Bent), Arundinaria, Melocalamus are used in manufacture of furniture.
Many grasses yield scented oils which are used in perfumery viz. Vetiveria zizanioides (H. Khus khus) yields vetiver oil from the roots. The roots are also woven into curtains. Andropogon odoratus (Ginger grass), Cymbopogon citratus (Lemon grass), Cymbopogon martini (Geranium grass), Cymbopogon jawarancusa etc. also yield oil.
Phragmites karka, Cymbopogon schoenanthus etc. are medicinal.
Secale cereale is cultivated for infection of its inflorescence by Claviceps purpurea for production of Ergot and for extraction of ergotine. Ergotine is an excellent remedy for uterine contraction.
It is manufactured from certain species of grasses and bamboos.
Rhynchelytrum repens, Cortaderia selloana and some species of the tribe Bambusoideae are ornamentals.
Besides these a number of grasses are grown to form fine lawns, play grounds etc.
Affinities of Poaceae:
The family Poaceae (Gramineae) closely resembles the family Cyperaceae and the two families have been placed in same order Glumiflorae by Engler and Prantl, and Glumaceae by Bentham and Hooker. Hutchinson (1964), Butzin (1965) and Takhtajan (1969) placed the families into 2 separate orders, the Cyperales and Graminales on the basis of many differences viz., 1. leaf sheath, 2. jointed and unjointed stem, 3. single bract and lemma and palea, 4. seed coat etc.
Cronquist (1968) considered that the families are also related on account of some chemical data. Hegnauer (1963) has also supported the same view.
Hutchinson (1959) believes that the origin of Grasses i.e., the family Poaceae (Gramineae) took place on parallel line with Cyperaceae through Juncaceae which was derived directly from Liliforean stock.