The grass genera of the world
Type species: Type: C. aculeata (L.) Ait.
Including Antitragus Gaertn., Ceytosis Munro, Heleochloa Hort ex Roem., Pallasia Scop., Pechea Lapeyr., Raddia Mazziari, Torgesia Bornm.
Habit, vegetative morphology. Annual; caespitose to decumbent. Culms 5–30 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes solid, or hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear (usually short); narrow; setaceous, or not setaceous; flat, or folded, or rolled; without abaxial multicellular glands; without cross venation; disarticulating from the sheaths; rolled in bud. Ligule a fringed membrane (narrow), or a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate (a panicle of contracted, bracteate panicles or heads, or a single, elongated-contracted panicle); open (when many-headed), or contracted (when only one head); spatheate (via enlarged, upper leaf sheaths), or espatheate; a complex of partial inflorescences and intervening foliar organs (e.g. C. aculeata), or not comprising partial inflorescences and foliar organs (e.g. C. alopecuroides). Spikelet-bearing axes disarticulating (the heads falling), or persistent; falling entire. Spikelets not secund; sessile.
Female-fertile spikelets. Spikelets 2–6 mm long; strongly compressed laterally; disarticulating above the glumes, or falling with the glumes, or not disarticulating. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.
Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas (almost equalling the floret); pointed; awnless; similar (narrow, complicate). Lower glume 0–1 nerved. Upper glume 0–1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas not becoming indurated (membranous); entire; awnless to mucronate; hairless; carinate; 1 nerved. Palea present; relatively long; entire, or apically notched, or deeply bifid; awnless, without apical setae; not indurated (hyaline); 1-nerved (Crypsis), or 2-nerved (Heleochloa). Lodicules absent. Stamens 2–3. Anthers 0.5–1.5 mm long, or 2–3 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 mm long); ellipsoid; compressed laterally, or not noticeably compressed; sculptured, or smooth. Hilum short. Pericarp free (sometimes becoming swollen when wet, extruding the seed). Embryo large. Endosperm hard. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (but the intercostals larger); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 19.5–24 microns long. Microhair basal cells 10–11 microns long. Microhairs 10.5–18 microns wide at the septum. Microhair total length/width at septum 1.3–2. Microhair apical cells 12–15 microns long. Microhair apical cell/total length ratio 0.57–0.63. Stomata common; 22–24 microns long. Subsidiaries dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare; in cork/silica-cell pairs and not paired (mainly paired, some solitary); silicified. Intercostal silica bodies present and perfectly developed; cross-shaped and oryzoid-type. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present throughout the costal zones to present in alternate cell files of the costal zones; panicoid-type.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles complete. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or nodular in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Cytology. Chromosome base number, x = 8 and 9. 2n = 16, 18, 32, 36, and 54. 2, 4, and 6 ploid. Chromosomes small.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Zoysieae; Sporobolinae (as a synonym of Sporobolus). 8 species.
Distribution, phytogeography, ecology. Mediterranean to North China.
Commonly adventive. Species of open habitats; halophytic, or glycophytic. Wet soils.
References, etc. Leaf anatomical: this project.
Illustrations. • C. schoenoides (as Heleochloa): Hitchcock and Chase (1950). • C. schoenöides: P. Beauv. (1812)
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’.