The grass genera of the world
Habit, vegetative morphology. Annual. Culms 10 cm high; herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 2–3 mm wide (1–2 cm long); flat (hairy); without cross venation; persistent. Ligule present; a fringe of hairs.
Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; female-only and male-only; overtly heteromorphic (the pedicellate, female spikelets hairy and long-awned, the sessile males hairless and awnless); all in heterogamous combinations.
Inflorescence. Inflorescence terminal, consisting of a pair of short racemes on a long peduncle. Primary inflorescence branches 2. Inflorescence spatheate (subtended by a spathiform sheath with reduced lamina). Spikelet-bearing axes racemes (3–4 noded only); the spikelet-bearing axes with 23 spikelet-bearing articles, or with 45 spikelet-bearing articles; paired (the pair fused by the lowest two joints); with substantial rachides (in proportion to their size); persistent. Spikelets paired (including the pair terminating the raceme); sessile and pedicellate; consistently in long-and-short combinations; in pedicellate/sessile combinations. Pedicels of the pedicellate spikelets free of the rachis. The shorter spikelets male-only. The longer spikelets female-only.
Female-sterile spikelets. The sessile male spikelets 3–4 mm long, with 1–2 awnless florets, the lower sterile, the upper with three stamens. Rachilla of male spikelets terminated by a male floret. The male spikelets with glumes; with proximal incomplete florets; usually 2 floreted. The lemmas awnless. Male florets 1; 3 staminate.
Female-fertile spikelets. Spikelets 2.5 mm long; falling with the glumes (deciduous from the cupular pedicel-tip). Rachilla terminated by a female-fertile floret.
Glumes two; more or less equal; long relative to the adjacent lemmas (exceeding them); hairy (densely brown-pilose); lanceolate, attenuate to more or less bifid apices; awnless; non-carinate; similar (but G2 narrower, less densely hairy). Lower glume not two-keeled; not pitted. Spikelets with female-fertile florets only (i.e., lacking the sterile andropogonoid L1); without proximal incomplete florets.
Female-fertile florets 1. Lemmas lanceolate, produced into the awn; less firm than the glumes (hyaline below, papery beneath the awn); not becoming indurated; entire; awned. Awns 1; median; apical; geniculate (bigeniculate); hairy; much longer than the body of the lemma (30 mm or more long); entered by one vein. Lemmas non-carinate; without a germination flap; 1 nerved. Palea present; conspicuous but relatively short (about 1 mm long - i.e., half lemma length); entire (oblong-acute); awnless, without apical setae; not indurated; keel-less. Stamens 0. Ovary apically glabrous. Styles fused (briefly). Stigmas 2.
Fruit, embryo and seedling. Fruit small. Hilum short. Embryo large (3/4 as long as the grain).
Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. Soreng et al. (2015): cf. Panicoideae (as a synonym?); Andropogonodae; Andropogoneae; Germainiinae. 1 species (C. thailandica).
Distribution, phytogeography, ecology. Thailand.
References, etc. Morphological/taxonomic: Bor 1968b; Chaianan 1972.
Special comments. Anatomical data wanting.
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’.