The grass genera of the world
Habit, vegetative morphology. Annual; erect or ascending. Culms 10–50 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; 1–3.5 mm wide; often rolled (convolute); without cross venation. Ligule an unfringed membrane; not truncate (lacerate); 3–6 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; contracted (the ends of the branches minutely hispidulous); spicate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 9–13 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus present, or absent.
Glumes two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas; free; pointed (acute); awnless; carinate, or non-carinate; similar (lanceolate). Lower glume 3 nerved. Upper glume 3–5 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 4–10. Lemmas similar in texture to the glumes (papery); not becoming indurated; entire, or incised; when entire, pointed; awned (apart from the lowest, which is acute and awnless). Awns 1; median; dorsal; from well down the back; geniculate; much longer than the body of the lemma (about 10 mm long); entered by one vein. Lemmas hairy, or hairless; non-carinate; without a germination flap; 5 nerved. Palea present; conspicuous but relatively short (about two thirds the lemma length); 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (2 mm long); compressed dorsiventrally. Hilum short. Embryo small. Endosperm liquid in the mature fruit.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (pitted and rather thick). Microhairs absent. Stomata common; 37.5–52 microns long. Subsidiaries parallel-sided. Guard-cells mostly only slightly overlapped by the interstomatals. Intercostal short-cells absent or very rare. Crown cells present. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous to horizontally-elongated smooth (few, shortish), or rounded (mainly).
Transverse section of leaf blade, physiology. C3; XyMS+.
Cytology. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 1 species (G. macra).
Distribution, phytogeography, ecology. Asia Minor.
References, etc. Leaf anatomical: studied by us.
Illustrations. • G. macra: Fl. Iraq, 1968
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 11th December 2017. delta-intkey.com/grass’.