Description:

• Annual or perennial herbs, rarely woody, very rarely tree-like, sometimes rhizomatous or stoloniferous, innovation shoots arising either intra- or extra-vaginally
• Culms (stems) mostly annual, even in perennials; erect, ascending, prostrate, decumbent or creeping, sometimes rooting at nodes, or floating, simple or branched; in perennials sterile and flowering culms mixed, in annuals only flowering culms present; culm usually cylindrical, sometimes flattened, jointed; internodes hollow, sometimes solid, with a soft, meristematic zone above each node; nodes solid; 2-keeled, hyaline prophylls present at base
• Leaves solitary, basal or cauline; alternate and 2-ranked, consisting of sheath, ligule and blade (lamina); sheath surrounding and supporting the culm, with margins free and overlapping or ± connate, with a meristematic zone at its base; ligule adaxial, situated at junction of blade and sheath, an unfringed or fringed membrane or fringe of hairs, rarely 0, or not present on all leaves, occasionally abaxial ligule also present, occasionally auricles present at base of blade or apex of sheath; blade usually long and narrow, rarely short and broad, flat, plicate, sometimes rolled, rolled inwards from one margin (convolute), rolled inwards from both margins (involute), or setaceous, occasionally blade consisting of midrib only, parallel-nerved, rarely with cross venation (transverse connections), usually passing gradually into sheath, sometimes amplexicaul or with sagittate base, rarely pseudopetiolate or articulated with sheath
• Inflorescence usually terminal, rarely axillary, ranging from a single spike to several, variously arranged spike-like branches to many-branched, open or condensed panicles or sometimes gathered into a leafy false panicle; spikelets, the basic flowering units borne in the inflorescence, are solitary, paired or 3- or 4-nate or clustered, sessile or pedicelled, or unequally pedicelled, pairs may be in long-short combinations: one sessile and one pedicelled spikelet; spikelets similar or dissimilar in sexuality on same inflorescence
• Spikelets typically consisting of a basal pair of subopposite empty bracts or glumes and 1 to several florets distichously arranged on an axis or rachilla and made up of several parts (basic pattern of spikelet structure consistent throughout family, though often with modification by reduction or suppression or elaboration of parts)
• Florets bisexual, unisexual or sterile, sometimes all mixed in the same spikelet, typically consisting of a subopposite pair of scale-like bracts: an outer (usually visible) lemma often produced into 1 or more awns or mucros; an inner palea usually more delicate than lemma; and a callus (horny prolongation) may occur at base of spikelet or lemma
• Lodicules (tiny scales taken to represent vestigial perianth members) 2(0 or 3)
• Stamens 3(1-6 or more), hypogynous, with 2-thecous anthers opening by longitudinal slits or rarely a terminal pore
• Ovary superior, 1-locular with a single anatropous (when mature) ovule, often adnate to adaxial side of carpel, and surmounted by 2(1 or 3) feathery stigmas
• Fruit mostly a caryopsis with thin pericarp adnate to seed, sometimes pericarp free, sometimes an achene, nut or berry; caryopsis commonly combined with various parts of spikelet, or less often inflorescence, to form a false fruit

Classification Notes:

• At present much work is being done on the higher classification of the grasses, and taxonomic understanding continues to improve.
• The system reflected in this work is based on that of Clayton & Renvoize (1986).
• The classification system of Watson & Dallwitz (1989, 1994) should also be consulted.

Nomenclature:

• Poaceae
  • Chippindall: 11 (1955)
  • Launert: 1 (1970)
  • Clayton: 1 (1970)
  • Launert: 1 (1971)
  • Clayton et al.: 177 (1974)
  • Clayton & Renvoize: 451 (1982)
  • Clayton & Renvoize: 1 (1986)
  • Gibbs Russell et al.: 1 (1990)
  • Watson & Dallwitz: (1994)

Distribution & Notes:

• Global: Genera ± 688; species ± 9500
• Southern Africa: Genera 192 (194) (29 exotic), species 912

References:

• CHIPPINDALL, L.K.A. 1955. A guide to the identification of grasses in South Africa. In D. Meredith, The grasses and pastures of South Africa. Central News Agency, Cape Town
• CLAYTON, W.D. 1970. Flora of tropical East Africa. Gramineae (Part 1)
• CLAYTON, W.D. & PHILLIPS, S.M. & RENVOIZE, S.A. 1974. Flora of tropical East Africa. Gramineae (Part 2)
• CLAYTON, W.D. & RENVOIZE, S.A. 1982. Flora of tropical East Africa. Gramineae (Part 3)
• CLAYTON, W.D. & RENVOIZE S.A. 1986. Genera graminum. Grasses of the world. Kew Bulletin. Additional series 13
• GIBBS RUSSELL, G.E., WATSON, L., KOEKEMOER, M., SMOOK, L., BARKER, N.P., ANDERSON, H.M. & DALLWITZ. M.J. 1990. Grasses of southern Africa. Memoirs of the Botanical Survey of South Africa No. 58
• LAUNERT, E. 1970. Gramineae. Prodromus einer Flora von Südwestafrika 160
• LAUNERT, E. 1971. Gramineae. Flora zambesiaca 10, 1
• WATSON, L. & DALLWITZ, M.J. 1989. The grass genera of the world, edn 3. CAB International, Oxon
• WATSON, L. & DALLWITZ, M.J. 1994. The grass genera of the world, revised edn. CAB International, Oxon

Resources:

• Classification of Poaceae
• Key to Poaceae genera

• Poaceae genera: