Chasmopodium Stapf
Habit, vegetative morphology. Robust annual, or perennial (rarely). Culms 90–550 cm high; herbaceous; branched above. Leaves not basally aggregated; non-auriculate. Leaf blades broad; 5–40 mm wide; pseudopetiolate; without cross venation; ligule present; a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and male-only, or hermaphrodite and sterile; homomorphic (except that the terminal spikelet is sometimes very long and thin).
Inflorescence. Inflorescence of cylindrical dorsiventral ‘racemes’, terminating the sparsely branching culms; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (the ‘racemes’ distant from their spathes). Spikelet-bearing axes ‘racemes’; solitary, or paired; with substantial rachides; disarticulating; disarticulating at the joints. ‘Articles’ non-linear (narrowed at the base, concave at the apex, shorter than the spikelets); with a basal callus-knob; not appendaged; disarticulating transversely; somewhat hairy (ciliate on the back). Spikelets paired; secund (the axis dorsiventral, the sessile spikelets in two anterior rows and alternating, the pedicelled members posterior); sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. Pedicels of the ‘pedicellate’ spikelets free of the rachis (stout). The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets male-only, or sterile.
Female-sterile spikelets. The pedicelled spikelet well developed. The lemmas awnless.
Female-fertile spikelets. Spikelets 6.3–7.5 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (there being an annulus of hairs, above the disarticulation knob).
Glumes two; more or less equal; long relative to the adjacent lemmas; hairless; awnless; carinate (G2), or non-carinate (G1); G2 with the keel conspicuously winged (towards the top, the two keels of G1 also somehwat winged); very dissimilar (leathery or crustaceous, the G1 flat or concave dorsally, the G2 naviculate). Lower glume two-keeled; flattened on the back to concave on the back; not pitted; relatively smooth; seemingly many nerved. Upper glume seemingly many 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 fully developed. The proximal incomplete florets male. The proximal lemmas awnless; 3 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas (hyaline); not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire; pointed, or blunt; awnless; hairless; non-carinate; without a germination flap; 3 nerved. Palea present; relatively long; entire; awnless, without apical setae; not indurated; 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous. Stigmas 2.
Fruit, embryo and seedling. Embryo large (about 4/5 the length of the caryopsis).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Costal zones with short-cells. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; ‘panicoid-type’; dumb-bell shaped.
Transverse section of leaf blade, physiology. C4 (‘bundles crowded’). Midrib conspicuous; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups (between the vascular bundles).
Phytochemistry. Leaves without flavonoid sulphates (1 species).
Cytology. Chromosome base number, x = 8. 2n = 16.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Rottboelliinae.
Distribution, ecology, phytogeography. 2 species; tropical Africa.
Paleotropical. African. Sudano-Angolan and West African Rainforest. Sahelo-Sudanian and South Tropical African.
References, etc. Leaf anatomical: Metcalfe 1960.
Special comments. Fruit data wanting.
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).