Including Chloridion Stapf
Habit, vegetative morphology. Annual, or perennial; stoloniferous, or caespitose. Culms 60150 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes hollow. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear to linear-lanceolate; narrow; 28(11) mm wide; flat; without cross venation; persistent; ligule present; a fringed membrane; 0.20.7 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches (slender spike-like racemes); paired or digitate. Primary inflorescence branches 28. Rachides winged (with narrow, fringed wings). Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes. The racemes spikelet bearing to the base, or without spikelets towards the base. Spikelet-bearing axes persistent. Spikelets paired; secund; biseriate; shortly pedicellate, or subsessile; consistently in long-and-short combinations (but homogamous). The shorter spikelets hermaphrodite. The longer spikelets hermaphrodite.
Female-fertile spikelets. Spikelets 24.5 mm long; abaxial; compressed dorsiventrally; flattened dorsally and ventrally; falling with the glumes; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.
Glumes one per spikelet, or two; minute, or relatively large (the G1 minute or absent, the G2 minute to almost as long as the spikelet); when both present, very unequal; (the upper) shorter than the spikelets to about equalling the spikelets; shorter than the adjacent lemmas to long relative to the adjacent lemmas; dorsiventral to the rachis; hairless; awned (G2 only, sometimes), or awnless; non-carinate; when both present, very dissimilar. Lower glume when present, 0 nerved. Upper glume 13 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, or epaleate (?). Palea of the proximal incomplete florets when present, reduced. The proximal incomplete florets sterile. The proximal lemmas awned (the terminal awn from 330 mm long); 5 nerved, or 7 nerved (in S. tridentata, the lateral keels form a tooth on either side of the awn); more or less equalling the female-fertile lemmas (excluding the awn); less firm than the female-fertile lemmas (membranous, scabrid, 2-keeled or not); not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (papery); not becoming indurated; brown in fruit; entire; pointed; awnless (sometimes apiculate); hairless; having the margins lying flat on the palea; with a clear germination flap; faintly 3 nerved. Palea present; relatively long; 2-nerved. Lodicules absent. Stamens 3. Anthers about 2 mm long; not penicillate; without an apically prolonged connective. Ovary glabrous. Styles fused. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small (about 1.7 mm long); elongate ellipsoid; compressed dorsiventrally. Hilum short (punctiform). Embryo large (about 1/3 the fruit length).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Intercostal zones with typical long-cells and exhibiting many atypical long-cells (varying from place to place). Mid-intercostal long-cells rectangular (elongated to almost square); having markedly sinuous walls. Microhairs present; panicoid-type; 7884 microns long; 4.56 microns wide at the septum. Microhair total length/width at septum 1318.7. Microhair apical cells 5152.5 microns long. Microhair apical cell/total length ratio 0.610.67. Stomata common; 3032(33) microns long. Subsidiaries parallel-sided (in some parts of the blade), or dome-shaped, or triangular; including both triangular and parallel-sided forms on the same leaf. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare (the apparent examples being prickle bases). Sometimes exhibiting macrohairs with complex cushion bases. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; nearly all cross shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS. PCR sheath outlines uneven. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells (apparently, in places). Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles (one large and up to 8 small bundles); with colourless mesophyll adaxially. Bulliforms not present in discrete, regular adaxial groups (bulliform cells constituting most of the epidermis). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 5 species; tropical east Africa. Mesophytic; species of open habitats; glycophytic. Savanna grasslands.
Paleotropical and Cape. African. Sudano-Angolan and West African Rainforest. Sahelo-Sudanian, Somalo-Ethiopian, South Tropical African, and Kalaharian.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia stenotaphri. Smuts from Ustilaginaceae. Ustilaginaceae Ustilago.
References, etc. Morphological/taxonomic: Stapf 1900b; Clayton 1978b. Leaf anatomical: this project.
Illustrations. General aspect. Abaxial epidermis of leaf blade. Transverse section of leaf blade
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).