The grass genera of the world
Habit, vegetative morphology. Perennial; rhizomatous, or rhizomatous and stoloniferous (occasionally). Culms 20–80 cm high; woody and persistent; to 4 cm in diameter; branched above. Culm nodes glabrous. Culm internodes solid. Plants conspicuously armed (with pungent tipped leaf blades and inflorescence axes). Young shoots intravaginal. Leaves mostly basal; non-auriculate. Leaf blades linear-lanceolate to lanceolate; narrow; to 6 mm wide; becoming rolled; hard, woody, needle-like; without abaxial multicellular glands; without cross venation; persistent. Ligule a fringe of hairs; to 2 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate (with distant branches, or reduced to a single branch or cluster); open (but the lateral branches compact). Primary inflorescence branches 4–25 (or more). Inflorescence usually with axes not ending in spikelets (these usually pungent-tipped, but sometimes terminating in a cluster of spikelets). Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; not two-ranked; pedicellate (the pedicels short); not imbricate.
Female-fertile spikelets. Spikelets 7–16 mm long; adaxial; compressed laterally; disarticulating above the glumes; disarticulating between the florets (tardily); with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (puberulous), or hairless; the rachilla extension with incomplete florets. Callus absent.
Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis; hairless; glabrous; pointed (but sometimes split at the tip); awnless; carinate; similar. Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless.
Female-fertile florets 3–16. Lemmas not saccate; similar in texture to the glumes; not becoming indurated; entire; pointed to blunt; awnless (muticous); hairless (sometimes puberulent); finely scaberulous or very finely puberulous; carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present; relatively long (equalling the lemmas or slightly shorter); entire; awnless, without apical setae; textured like the lemma (membranous); not indurated; 2-nerved; 2-keeled. Palea keels wingless (but usually puberulous). Lodicules present; 2; free; fleshy. Stamens 3. Anthers 1.5–2 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.3 to 2 mm long); compressed dorsiventrally. Hilum short. Pericarp free. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular. Microhairs present (but hidden in the deep intercostal grooves of the lamina); elongated; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhair basal cells 30 microns long. Microhair total length/width at septum 3.4. Microhair apical cell/total length ratio 0.3. Stomata common. Intercostal short-cells not paired. Intercostal silica bodies absent. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (the rows with many prickles). Costal silica bodies present in alternate cell files of the costal zones; saddle shaped (to squarish).
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4. The anatomical organization fairly conventional. XyMS+. PCR sheath outlines uneven (owing to the adaxial extensions). PCR sheaths of the primary vascular bundles complete. PCR sheath extensions present (with most bundles). Maximum number of extension cells 4–5. PCR cell chloroplasts centripetal. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells (between each pair of bundles). Leaf blade nodular in section; with the ribs more or less constant in size (the abaxial ribs somewhat broader and flatter than their adaxial counterparts, the grooves between them narrow). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in each adaxial groove); associated with colourless mesophyll cells to form deeply-penetrating fans (these linking with the heavy colourless columns). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures (all the bundles with conspicuous Is or anchors). Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Eragrostideae; Eragrostidinae. 2 species.
Distribution, phytogeography, ecology. Southern Africa.
Xerophytic; species of open habitats; halophytic, or glycophytic. C. cyperoides on beach dunes, C. spinosa on desert dunes and in sandy beds of dry watercourses.
References, etc. Leaf anatomical: photos of C. cyperoides provided by R.P. Ellis; Van den Borre 1994 (C. spinosa).
Illustrations. • C. spinosa, as Poa: Kunth (1835). • C. spinosa: Gibbs Russell et al., 1990
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’.