The grass genera of the world
Habit, vegetative morphology. Annual. Culms 10–40 cm high; herbaceous. Leaves not basally aggregated; non-auriculate. The upper sheaths inflated. Leaf blades linear (acuminate); narrow; flat. Ligule an unfringed membrane; not truncate; 1 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate (but peculiar - the spikelets in numerous small, compact panicles, each of these enclosed by a leathery, toothed involucre at the tip of a stout, recurved peduncle; the peduncles themselves subtended by the inflated sheaths of the upper leaves); spatheate (the inflorescence units enclosed in tough, toothed involucres); a complex of partial inflorescences and intervening foliar organs. Spikelet-bearing axes capitate; disarticulating; falling entire (the heads falling whole). Spikelets associated with bractiform involucres (each head surrounded by a cup-shaped involucral bract, which is is deciduous with it). The involucres shed with the fertile spikelets. Spikelets not secund; subsessile to pedicellate (the pedicels short).
Female-fertile spikelets. Spikelets more or less unconventional; 4–7 mm long; compressed laterally; falling with the glumes (in the heads). Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; more or less equal; long relative to the adjacent lemmas; joined (in the lower third); hairless (but the keel ciliate below); not pointed (round or emarginate); awnless; carinate; similar. Lower glume 3 nerved. Upper glume 2–3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas truncate; similar in texture to the glumes (the margins connate over the lower half); not becoming indurated; entire; blunt; awnless, or awned. Awns when present, 1; dorsal; from well down the back; non-geniculate; much shorter than the body of the lemma; entered by one vein. Lemmas hairless; non-carinate; without a germination flap; 5 nerved. Palea absent. Lodicules absent. Stamens 3. Ovary apically glabrous. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.5–2 mm long); compressed laterally. Hilum short. Embryo small. Endosperm hard; with lipid; containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally, or markedly different in shape costally and intercostally (the costals bulbous between the silica cells); of similar wall thickness costally and intercostally, or differing markedly in wall thickness costally and intercostally (the costals thicker walled). Mid-intercostal long-cells rectangular and fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common, or absent or very rare; (27–)39(–60) microns long. Subsidiaries non-papillate; parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. With a few small costal prickles. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (mostly solitary). Costal silica bodies present and well developed; horizontally-elongated crenate/sinuous (large and conspicuous).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade nodular in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms unclear, in the material seen. All the vascular bundles accompanied by sclerenchyma (but this scanty). Combined sclerenchyma girders absent (each bundle associated with small adaxial and abaxial strands). Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Spikelets in numerous small, compact, short-branched panicles, each panicle at the tip of a stout, recurved peduncle and enclosed by a leathery, toothed involucre, the peduncles themselves subtended by the inflated sheaths of the (modified) upper leaves.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 2 species.
Distribution, phytogeography, ecology. Eastern Mediterranean.
References, etc. Leaf anatomical: this project.
Illustrations. • C. cucullatum: 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: 13th November 2017. delta-intkey.com/grass’.