The grass genera of the world
~ Brachiaria sensu lato
Habit, vegetative morphology. Perennial. Culms 7–100 cm high; woody and persistent (stiffly geniculate); branched above (the plants bushy). Culm nodes glabrous. Culm internodes solid. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear-lanceolate; narrow; 2–4 mm wide; flat, or rolled; hard, woody, needle-like (sometimes spiny, hard and brittle), or not needle-like; not pseudopetiolate; without cross venation; disarticulating from the sheaths (leaving the culms as the main organs of photosynthesis). Ligule a fringe of hairs; 0.6–0.8 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary, or paired; not secund; pedicellate (and substipitate, with a short stalk fitting into the pedicel apex). Pedicel apices cupuliform. Spikelets consistently in long-and-short combinations, or not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets 4–6 mm long; abaxial to adaxial (the orientation variable); compressed dorsiventrally; biconvex; falling with the glumes; not disarticulating between the florets; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.
Glumes two; relatively large; very unequal to more or less equal; about equalling the spikelets to exceeding the spikelets; (the longer) long relative to the adjacent lemmas; hairy; with distinct rows of hairs (the upper with a transverse row above the middle, the lower glabrous save at the base); pointed (the tips minutely truncate); awnless (but the tips caudate, inrolled, membranous); non-carinate; very dissimilar (the lower obtuse or notched at the apex, pilose at the base, the upper tapering, caudate, dorsally long-villous with a transverse fringe just above the middle). Lower glume 0.75–1 times the length of the upper glume; about equalling the lowest lemma; 3 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets fully developed; not becoming conspicuously hardened and enlarged laterally. The proximal incomplete florets male. The proximal lemmas awnless (the tip inrolled, membranous, sometimes slightly caudate, the back with a transverse fringe of hairs); 3 nerved; decidedly exceeding the female-fertile lemmas (about twice as long); less firm than the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes; smooth; becoming indurated (glossy); entire; pointed, or blunt; awnless; hairless; glabrous; non-carinate; having the margins inrolled against the palea; with a clear germination flap (basal); 5 nerved. Palea present; relatively long; tightly clasped by the lemma; entire; awnless, without apical setae; textured like the lemma; indurated; 2-nerved; 2-keeled. Palea keels glabrous. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers 2–2.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals relatively longer and narrower). Intercostal zones with typical long-cells. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type. Stomata common. Subsidiaries mostly dome-shaped. Intercostal short-cells common; seemingly not paired. With rosettes of isodiametric cells around each of the abundant macrohairs. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS+. PCR sheath extensions absent. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (and also some rather irregular groups); in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present (with the major ones only); nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melidininae. 3 species.
Distribution, phytogeography, ecology. Tropical and southern Africa.
Helophytic, or xerophytic; species of open habitats; glycophytic. Sandy riverbeds in semidesert.
References, etc. Morphological/taxonomic: Rendle 1922; Launert 1970. Leaf anatomical: photos of L. mesocoma provided by R.P. Ellis.
Special comments. Fruit data wanting. Illustrations. • L. mesocoma: Hook. Ic. Pl. 31 (1922). • General aspect (L. mesocoma): 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’.