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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Chaetopogon Janchen

Including Chaeturus Link

Habit, vegetative morphology. Annual. Culms 3–30 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; narrow; 0.5–1.5 mm wide; setaceous, or not setaceous; without cross venation. Ligule an unfringed membrane; not truncate (acute); 3–5 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence paniculate; contracted (narrow); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; shortly pedicellate.

Female-fertile spikelets. Spikelets 2.8–3 mm long; compressed laterally; falling with the glumes (and with the short pedicel). Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; very unequal to more or less equal; exceeding the spikelets; long relative to the adjacent lemmas; hairless; scabrous; (the lower only) awned; carinate, or non-carinate; very dissimilar (linear lanceolate, membranous, the lower produced into a long slender awn, the upper awnless). Lower glume 1–3 nerved. Upper glume 1–3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas less firm than the glumes to similar in texture to the glumes (hyaline); not becoming indurated; entire, or incised; pointed; not deeply cleft; awned. Awns 1; median; from a sinus, or apical; non-geniculate; much shorter than the body of the lemma to about as long as the body of the lemma (?); entered by one vein. Lemmas hairless; non-carinate; without a germination flap; 1 nerved, or 3 nerved. Palea present; conspicuous but relatively short (about half as long as the lemma); apically notched (denticulate); awnless, without apical setae; not indurated (hyaline); 1-nerved, or nerveless; keel-less. Lodicules present; 2; free; membranous; glabrous; not toothed; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small (about 2 mm long); compressed dorsiventrally. 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; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular and fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata fairly common; about 45 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (but so deeply ‘crenate’ as almost to qualify as ‘nodular’).

Transverse section of leaf blade, physiology. XyMS+.

Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Agrostidinae. 2 species.

Distribution, phytogeography, ecology. Mediterranean.

References, etc. Leaf anatomical: studied by us - C. fasciculatus Link.

Special comments. Anatomical data epidermal only. Illustrations. • C. fasciculatus, as Chaeturus: Kunth (1835)

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.’.