| # The grass genera of the world |

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

### Ctenopsis De Not

From the Greek ktenos (a combe) and opsis (appearance), alluding to a comblike inflorescence.

~ Festuca, Vulpia

Habit, vegetative morphology. Annual; caespitose. Culms 10–40 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; setaceous; rolled (convolute); without cross venation; persistent. Ligule an unfringed membrane; 0.7–1 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence a single raceme, or paniculate (sometimes sparingly branched); contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund (pectinate); pedicellate.

Female-fertile spikelets. Spikelets 3.5–12 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless. Hairy callus absent.

Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; dorsiventral to the rachis; pointed; awnless; non-carinate (rounded on the back); very dissimilar (the lower minute). Lower glume 0 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets.

Female-fertile florets 3–14. Lemmas acuminate; less firm than the glumes (papery, the margins hyaline); not becoming indurated; entire; pointed; awnless, or mucronate (?); hairless; non-carinate; 5 nerved. Palea present; relatively long; apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed. Stamens 3. Anthers 0.5–2.5 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small; longitudinally grooved; compressed dorsiventrally. Hilum short. Embryo small; not waisted.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous to lacking. 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. Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs (mostly - some solitary); silicified (rarely), or not silicified. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Midrib conspicuous; with one bundle only. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (C. pectinella), or absent (C. patens); in C. pectinella forming ‘figures’ (having tall, narrow I’s with most bundles). Sclerenchyma all associated with vascular bundles.

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

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 4 species.

Distribution, phytogeography, ecology. Mediterranean & western Asia.

Species of open habitats.

References, etc. Leaf anatomical: studied by us - C. patens (Boiss.) Meld., C. pectinella (Del.) De Not.

Illustrations. • Ctenopsis pectinella: Bor, Flora of 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: 15th June 2025. delta-intkey.com’.

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