The grass genera of the world
Type species: Type: C. loliaceum (Huds.) Link.
Including Scleropoa Griseb., Synaphe Dulac
Habit, vegetative morphology. Annual; caespitose (or the culms solitary). Culms 10–50(–60) cm high; herbaceous; sparsely branched above, or unbranched above; 2–7 noded. Culm nodes exposed, or hidden by leaf sheaths; glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; apically flat; narrow; 1–4.8 mm wide; flat, or folded, or rolled (sometimes involute or convolute when dry); without cross venation; persistent. Ligule an unfringed membrane; truncate; 0.5–3 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality. Plants inbreeding; exposed-cleistogamous, or chasmogamous.
Inflorescence. Inflorescence a single raceme, or paniculate (rigid, spikelike, with or without branches in the proximal part); open, or contracted (the branches with small adaxial pulvini); without conspicuously divaricate branchlets. Primary inflorescence branches when these occur, borne biseriately on one side of the main axis. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets secund (appressed to one side of the axis); biseriate; pedicellate (the pedicels short, thick).
Female-fertile spikelets. Spikelets 4–9(–10.2) mm long; oblong, or elliptic; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes present; two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; lateral to the rachis; pointed; awnless; carinate; very dissimilar to similar (leathery, the lower lanceolate, the upper ovate). Lower glume 1–3 nerved. Upper glume 1 nerved, or 3 nerved, or 5 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1; merely underdeveloped (much reduced); awnless.
Female-fertile florets (3–)4–11(–12). Lemmas dorsally rounded and glabrous basally, by contrast with Desmazeria; less firm than the glumes to similar in texture to the glumes (membranous or leathery); not becoming indurated; entire; blunt; awnless; hairless; glabrous (at least towards the base); non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; tightly clasped by the lemma; 2-nerved; 2-keeled. Palea keels wingless. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed. Stamens 3. Anthers 0.4–0.9 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 (1.5–2 mm long); ellipsoid; shallowly longitudinally grooved (ventrally); compressed dorsiventrally (ventrally). Hilum short. Embryo small; not waisted. Endosperm hard; with lipid. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Seedling with a tight coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; 3 veined.
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 (thin walled). Mid-intercostal long-cells rectangular; having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare (C. loliaceum), or common (C. rigidum); in C. rigidum 24–30 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals, or overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare; when present, in cork/silica-cell pairs; silicified. Costal short-cells neither distinctly grouped into long rows nor 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. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Lemmas not as in Briza (q.v.).
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes large. Mean diploid 2c DNA value 9.6 pg.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Parapholiinae. 2 species.
Distribution, phytogeography, ecology. Europe, Mediterranean.
Commonly adventive. Mesophytic to xerophytic; species of open habitats; halophytic, or glycophytic. In dry microhabitats, including maritime sand.
Economic aspects. Significant weed species: C. rigidum.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis and Uromyces dactylidis.
References, etc. Leaf anatomical: Metcalfe 1960 and this project.
Illustrations. • C. rigidum (as Sclerochloa rigida), general aspect: Eng. Bot. (1872). • C. rigidum, general aspect: J. Curtis, 1824. • C. rigidum: Gardner, 1952. • C. rigidum: Gibbs Russell et al., 1990. • C. marinum (as Sclerochloa loliacea), general aspect: Eng. Bot. (1872). • C. marinum, inflorescence detail. • C. marinum, spikelet
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’.