Brachiaria (Trin.) Griseb.
From the Latin brachium (arm), alluding to the manner of bearing the racemes.
Habit, vegetative morphology. Annual (mostly), or perennial (sometimes in B. schoenfelderi); stoloniferous, or caespitose, or decumbent. Culms (10)25100 cm high; herbaceous; unbranched above (?); 36 noded. Culm nodes hairy. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear to lanceolate; narrow; 38(11) mm wide (and 215(-18) cm long); flat, or rolled; without cross venation; persistent; rolled in bud; a fringe of hairs. Contra-ligule absent.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets; outbreeding (?). Apomictic, or reproducing sexually (?).
Inflorescence. Inflorescence of spicate main branches, or paniculate (the basal racemes sometimes with secondary racemelets). Primary inflorescence branches 417 (?); borne biseriately on one side of the main axis. Inflorescence with axes ending in spikelets. Rachides hollowed (or triquetrous), or winged. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; solitary; secund; biseriate; pedicellate (the pedicels 0.20.5 mm long). Pedicel apices concave, discoid. Spikelets imbricate; not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets 1.63.7 mm long; broadly elliptic; adaxial; compressed dorsiventrally; biconvex; primarily disarticulating above the glumes (at the base of the upper floret, but with a secondary disarticulation beneath the glumes); disarticulating between the florets (this distinguishing Brachiaria sensu stricto from Urochloa sensu lato). Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.
Glumes two; very unequal (the lower a small scale); long relative to the adjacent lemmas (i.e. the upper glumes); dorsiventral to the rachis; hairy, or hairless, or hairy and hairless (the lower usually glabrous); awnless; non-carinate; very dissimilar (the lower much reduced, the upper similar to the L1). Lower glume 01 nerved. Upper glume 35 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, or sterile. The proximal lemmas awnless (muticous); 35(7) nerved (the laterals distant from the median); more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas; not becoming indurated (membranous).
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (chartaceous to cartilaginous); smooth (and shiny); becoming indurated to not becoming indurated; white in fruit; entire; blunt; not crested; awnless; hairless; glabrous; non-carinate; having the margins inrolled against the palea; with a clear germination flap; obscurely 35 nerved. Palea present (the tip not reflexed); relatively long; tightly clasped by the lemma; entire (apically rounded); awnless, without apical setae; textured like the lemma; indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Embryo large. Endosperm hard; without lipid. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (rarely), or absent (?). Intercostal papillae not over-arching the stomata. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; (32)4067(76) microns long (?). Microhair apical cells (18)2648 microns long (?). Microhair apical cell/total length ratio 0.520.69 (?). Stomata common. Subsidiaries dome-shaped, or triangular (?). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare (?); in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; cross shaped, or butterfly shaped, or dumb-bell shaped, or nodular (?).
Transverse section of leaf blade, physiology. C4; biochemical type PCK; XyMS+. PCR sheath outlines uneven. PCR sheath extensions present, or absent (?). Maximum number of extension cells if present, 1. PCR cells with a suberised lamella. PCR cell chloroplasts ovoid; with well developed grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade nodular in section to adaxially flat (?). Midrib conspicuous, or not readily distinguishable (?); with one bundle only, or having a conventional arc of bundles (?); without colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans, or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (?). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present, or absent (?); nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves without flavonoid sulphates (?).
Cytology. Chromosome base number, x = 9. 2n = 18. 2 ploid. Chromosomes small. Nucleoli persistent.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 3 species (B. eruciformis, B. malacodes, B. schoenfelderi); Africa and Mediterranean. Commonly adventive (notably B. eruciformis). Mesophytic; shade species, or species of open habitats; glycophytic.
Holarctic, Paleotropical, and Cape. Boreal and Tethyan. African and Madagascan. Macaronesian, Mediterranean, and Irano-Turanian. Saharo-Sindian, Sudano-Angolan, West African Rainforest, and Namib-Karoo. Sahelo-Sudanian, Somalo-Ethiopian, South Tropical African, and Kalaharian.
Rusts and smuts. Rusts Physopella and Puccinia. Taxonomically wide-ranging species: Puccinia orientalis, Puccinia levis, and Uromyces setariae-italicae. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Melanotaenium and Tilletia. Ustilaginaceae Sorosporium, Sphacelotheca, Tolyposporella, and Ustilago.
Economic importance. Significant weed species: B. eruciformis.
References, etc. Morphological/taxonomic: Webster (1987), Morrone and Zuloaga (1992 and 1993), Veldkamp (1996). Leaf anatomical: Metcalfe 1960 and this project.
Special comments. For justification of this sensu stricto interpretation, see Webster (1987), Morrone and Zuloaga (1992), and Veldkamp (1996). In Watsons opinion, however, it would have been better to delay such realignments until generic circumscriptions around Panicum had been broadly reassessed on a basis of worldwide sampling.
Illustrations. Abaxial epidermis 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).