GRAMINEAE (POACEAE)

Class : MonocotyledonsSeries : Glumaceae

Family : Poaceae

668 genera,9500 species (1997)The family is cosmopolitan in distribution

Etymology

The Poaceae name was given by John Hendley Barnhart in 1895, based on the tribe Poeae (described in 1814 by Robert Brown), and the type genus Poa (described in 1753 by Linnaeus). The term is derived from the Ancient Greek term for grass.

Diagnostic Characters1. Mostly annual herbs with fistular stem 2. Leaves distichous with sheathing bases and

ligule3. Inflorescence unit is a spikelet4. Perianth is reduced to lodicules or even

absent 5. Anthers are versatile 6. Stigma are feathery7. Fruit is caryopsis

Common plantsAlloteropsis cimicina Bambusa bambos

Coix lacryma - jobi

Eleusene coracana

Oplismenus burmanii

Oryza sativa Pennisetum polystachyon

Rottboellia exatlata

Saccharum officinale

Habit : 1.mostly annual (Oryza) or perennial (Sacharum) herbs

Roots :Fibrous and mainly plant possess rhizomes

Stem :1.Stem of grasses is called a culm 2.It is usually fistula or hollow 3.The stem is erect ,prostrate or creeping

Leaves: Simple Alternate Parallel venation Exstipulate : stipule absent Distichous Ligulate : Preventing water or insect from penetrating in to the sheath.

Inflorescence Flowers of poaceae are characteristically arranged

in spikelets .Each spikelet has a very short or minute axis

called RachillaSpikelet having one or more floretsA spikelets consist 2 bracts at the base Glumes

and followed by one or more florets A floret consist of the flower surrounded by 2

bracts one external lemma & one internal paleaPerianth is absent or reduced to scales -----

lodicules

Flowers : Small Bracteates Bracteolate (Lemma & Palea) Sessile Usually Bisexual (Oryza ) ,Rarely Unisexual (Zea) Hypogynous Zygomorphic

Androecium : stamens are usually 3 and belong to outer whorl. The inner whorl of stamens is generally completely absent . Anthers are dithecous , versatile and introse &which open by a longitudinal slit .

The stamens are 6 , arranged in 2 whorls of 3 each in Bambusa and Oryza

The stamens are numerous in Pariana.

Gynoecium : Bi or tricarpellary and syncarpous or monocarpellary & superior .

It is always unilocular with a single ovule on basal placentation

Styles usually 2 (rarely 1 or 3 0r absent) and 3 in Bambusa .

Stigmas are 2 and feathery

Fruit : A caryopsis ( fruit wall is completely fused with the seed coat)

Advanced characters

Herbaceous , annual or perennial habitExstipulate leaves with sheathing bases and ligulesFlowers arranged in distinct inflorescence called spikeletHighly reduced , inconspicuous and zygomorphic flowersPerianth is represented by lodicules Reduction in the number of stamens to threeMonocarpellary and unilocular ovary with a single ovule on

basal placentaFruit is a caryopsis

Plants of economic importantsFood: this family consists of the most important food plants called cerealsWheat (Triticum aestivum)Rice (Oryza sativa )Maize (zea mays)Barley (Hordeum vulgare)Oats (Avena sativa)Ragi (Eleusine coracana)

Paper : Bambusa and dendrocalamus yield bamboos .Paper pulp is made out of bamboos

Medicinal : Roots of Vetiveria zizanioides are medicinal and give a pleasant scent

Valuable perfumery oils are obtained from Cymbopogon citratus (lemon grass) and Andropogon odonatus (ginger grass)

Ornamental : Cynodon (Bermuda grass) , Agrostis (florin grass) , Poa (meadow grass) and Festuca (festuca grass) are grown in lawns.