The grass genera of the world
Habit, vegetative morphology. Perennial; caespitose. Culms 5–40 cm high; herbaceous; to about 0.1 cm in diameter; unbranched above. Culm nodes glabrous. Culm internodes solid. Plants unarmed. Young shoots intravaginal. Leaves mostly basal; non-auriculate. Leaf blades linear; narrow; to 1 mm wide; becoming setaceous; folded, or rolled (rarely flat); without abaxial multicellular glands; without cross venation; persistent. Ligule a fringe of hairs; 0.3 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches (spiciform, of numerous short racemes); contracted (very much so - the lateral branches short, sometimes reduced to 4 or 5 spikelets); non-digitate; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; shortly pedicellate.
Female-fertile spikelets. Spikelets 4–5 mm long; compressed laterally; falling with the glumes (seeming to disarticulate at the base of the pedicel). Rachilla prolonged beyond the uppermost female-fertile floret (the prolongation small); the rachilla extension naked. Hairy callus present (the i.e., the pedicel).
Glumes two; (the upper) relatively large; very unequal; the upper exceeding the spikelets; (the upper) long relative to the adjacent lemmas; lateral to the rachis; hairless (glabrous, ciliolate on the keel); pointed; awnless; (the upper) carinate; very dissimilar (the lower reduced to a small subulate scale, the upper lanceolate). Lower glume much shorter than half length of lowest lemma; 0 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 1 (lanceolate). Lemmas similar in texture to the glumes (thin); not becoming indurated; entire; pointed; awnless; hairy. The hairs in tufts (one or two on either flank); not in transverse rows. Lemmas scabrous on the keels; carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present (broad); relatively long; apically notched (emarginate); awnless, without apical setae; textured like the lemma (hyaline, glabrous); not indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers 1.5–2 mm long (i.e. relatively long); not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles fused. Stigmas 2; light brown.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (fairly thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (and pitted). Microhairs present; elongated; clearly two-celled; panicoid-type (very large, the apical cells narrow and often collapsed, but relatively short and round-tipped). Microhair apical cell wall thinner than that of the basal cell but not tending to collapse. Microhair basal cells 33 microns long. Microhair total length/width at septum 5. Microhair apical cell/total length ratio 0.3. Stomata common. Subsidiaries low to high dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies present and perfectly developed; tall-and-narrow, or cross-shaped. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; assorted rounded, saddle shaped, and panicoid-type; when panicoid type, cross shaped, or dumb-bell shaped, or nodular.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines uneven. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions present. Maximum number of extension cells 1. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs to nodular in section; with the ribs more or less constant in size (low, round-topped). Midrib conspicuous (somewhat: a larger bundle and keel, with heavier sclerenchyma); with one bundle only. Bulliforms present in discrete, regular adaxial groups (between all the bundles); in simple fans (each group with a large, deeply penetrating median cell). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (in the primaries only, the small bundles with abaxial girders and adaxial strands); forming figures (in the primary bundles). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Eragrostideae; Eragrostidinae. 1 species (C. gracilis).
Distribution, phytogeography, ecology. South Africa.
Mesophytic (locally abundant in mountain grassland); species of open habitats.
References, etc. Leaf anatomical: studied by us; photos provided by R.P. Ellis.
Special comments. Fruit data wanting. Illustrations. • C. gracilis: Gibbs Russell et al., 1990. • C. gracilis, abaxial epidermis of leaf blade: this project. • C. gracilis, abaxial epidermis of leaf blade: this project
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’.