The grass genera of the world
Habit, vegetative morphology. Perennial; rhizomatous, or stoloniferous. Culms 30–100 cm high; herbaceous; branched above. Culm nodes glabrous. Leaves not basally aggregated; non-auriculate. Sheath margins free. Leaf blades lanceolate; broad; slightly cordate, or not cordate, not sagittate; pseudopetiolate, or not pseudopetiolate; cross veined. Ligule a fringed membrane.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (sometimes sterile at the base of the inflorescence).
Inflorescence. Inflorescence of spicate main branches (mostly), or paniculate (the branches sometimes themselves branched at the base); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets in triplets (or small clusters), or paired; secund (the racemes unilateral); pedicellate; not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets 6–8 mm long; abaxial; compressed laterally; falling with the glumes. Rachilla prolonged beyond the uppermost female-fertile floret (the prolongation minute, vestigial), or terminated by a female-fertile floret; the rachilla extension when present, naked. Hairy callus absent.
Glumes two; very unequal; shorter than the adjacent lemmas, or long relative to the adjacent lemmas (i.e., the upper glumes); dorsiventral to the rachis; hairy (with very large, sparse hairs, or stiff, tubercle-based bristles); pointed (acuminate); awnless; non-carinate; similar (membranous-herbaceous). Lower glume 3–5 nerved. Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets reduced. The proximal incomplete florets sterile. The proximal lemmas similar to the glumes, hairy or bristly; awnless; 7–8 nerved; decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas narrow; similar in texture to the glumes to decidedly firmer than the glumes (somewhat papyraceous); smooth (shining); not becoming indurated; entire; pointed; awnless to mucronate; hairless; glabrous (shiny); non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; entire (acute); awnless, without apical setae; textured like the lemma; not indurated; 2-nerved; 2-keeled (folded on the margins). Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit small; compressed laterally (plano-convex). Hilum short. Embryo large; waisted.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Intercostal zones exhibiting many atypical long-cells to without typical long-cells. Mid-intercostal long-cells rectangular; having markedly sinuous walls (coarsely, deeply). Microhairs present; panicoid-type; (69–)81–83 microns long; (30–)48–51(–53) microns wide at the septum. Microhair total length/width at septum 12.8–16.9. Microhair apical cells 4.8–5.7 microns long. Microhair apical cell/total length ratio 0.43–0.74. Stomata common; about 33 microns long. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (apparently solitary); silicified. Intercostal silica bodies tall-and-narrow. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade nodular in section to adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (bulliform-like cells constituting most of adaxial epidermis). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae. 2 species.
Distribution, phytogeography, ecology. Tropical Africa.
References, etc. Leaf anatomical: this project.
Illustrations. • C. oplismenoides: Jacques-Félix, 1962. • C. oplismenoides, as C. secunda: Hook. Ic. Pl. 31 (1916)
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’.