Biology XI Content
Graminae is the largest family among monocotyledon plants. It compromises about 6.68 genera and 9500 species. In Nepal, there are 115 genera and 406 species.
Usually, the species of graminae found in almost all kind of habitats. Majority of them are mesophytes, few species are hydrophytes and xerophytes.
Usually, annual herb, perrineal herbs and shrubs, rarely trees or climbers. Bambo is the largest tree-like species belonging to this family.
Adventitious, fibrous, some plants like maize, sugarcane possess stilt roots.
Aerial, crest, usually herbaceous, cylindrical or angular stem usually possesses distinctly nodes and internodes (called as culms) usually branched from base of stem, branches are called tillers, usually fistular, sometimes solid, sometimes stem is prostrate and sub-taranean, hairy.
Usually cauline, sometimes radical, leaf is divisible into sheath and lamina, sheath often encircled around the internocle of stem, at the juncture of sheath and lima, ligule another extra appendages called auricle is present, lamina is long, narrow and linear, apex and acuminate surface silicate.
Usually racemose, spike or spilelet, sometimes paniculate spike. Each spikelets consists of one or few flowers borne alternately, surrounded at the base by two opposite sterile called glumes. Each flower has two bracts, the lower bract is called lemma and the upper inner bract is called pelea. Lemma has a long awn as an extension of midrib at the apex. The axis of inflorescence is called rachis and the central stalk of spikelet is called rachilla.
Sessile, bracteates, bisexual, unisexual, zygomorphic, incomplete, hypogynous
Represented by two minute membranous scales called lodicules (e.g. Bambusa), inferior.
Stamens-3, sometimes six (e.g. Oryza) in two whorls, free filaments, long and slender, anthers bicelled, versatile, inferior.
Caryopsis with single seed (grain)
Usually anemophilous, cross pollination also takes place.