The grass genera of the world
Habit, vegetative morphology. Perennial; caespitose (with short, creeping rhizomes). Culms 26–93 cm high; herbaceous; to 0.2 cm in diameter; unbranched above. Culm nodes glabrous. Culm internodes solid. Plants unarmed. Young shoots intravaginal. Leaves mostly basal; non-auriculate; without auricular setae (but hairy at the mouth of the sheath and on the lower part of the blade). Leaf blades linear to linear-lanceolate; narrow; to 5 mm wide; flat, or rolled (the margins becoming involute under water stress); without abaxial multicellular glands; without cross venation. Ligule an unfringed membrane (minutely ciliolate only); truncate; to 0.3 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence of spicate main branches (these appressed to the central axis). Primary inflorescence branches about 10–15. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes racemes. The racemes spikelet bearing to the base. Spikelet-bearing axes persistent. Spikelets solitary; somewhat secund; biseriate; shortly pedicellate; imbricate.
Female-fertile spikelets. Spikelets 5.5–9 mm long; adaxial; strongly compressed laterally; disarticulating above the glumes; not disarticulating between the florets; with conventional internode spacings (rather long). Rachilla prolonged beyond the uppermost female-fertile floret; hairy (between L1 and L2); the rachilla extension with incomplete florets. Hairy callus present. Callus short; blunt.
Glumes two; more or less equal; about equalling the spikelets (a little shorter to a little longer); long relative to the adjacent lemmas; dorsiventral to the rachis; hairless (scabridulous); pointed (acuminate, often mucronate); awnless; strongly carinate; similar. Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 2–6. Lemmas similar in texture to the glumes (membranous); not becoming indurated; entire, or incised; not deeply cleft (no more than minutely notched); awned. Awns 1; median; dorsal; from a quarter to a third of the way down; non-geniculate; hairless (scabrid); much shorter than the body of the lemma to about as long as the body of the lemma (1–4 mm long); entered by one vein. Lemmas hairy (the lower lemmas hairy below, beside the keel and on the margins); carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present; relatively long; minutely apically notched; awnless, without apical setae; textured like the lemma; not indurated; 2-nerved; 2-keeled. Palea keels hairy (minutely, densely ciliate). Lodicules present; 2; free; fleshy (long, narrow); glabrous. Stamens 3. Anthers 1.5–2.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small (about 2 mm long); linear (to oblong); not noticeably compressed (terete). Pericarp fused.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells of similar wall thickness costally and intercostally (fairly thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata common (in rather distant single files). Subsidiaries parallel-sided to triangular (rather irregular - mostly high domes with truncated tops). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (solitary); not silicified (in material seen). Intercostal silica bodies absent. Prickles abundant. Costal short-cells conspicuously in long rows (the files interrupted by prickles). Costal silica bodies present and well developed (usually?), or absent (in some material seen, but the silica cells nodular); present in alternate cell files of the costal zones; panicoid-type; dumb-bell shaped (with long, inconspicuous isthmuses), or nodular (a few).
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+ (the MS thick-walled, sometimes double). PCR sheath outlines even. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions absent. PCR cell chloroplasts centripetal. Leaf blade adaxially flat (or with very low flat-topped ribs). Midrib conspicuous to not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming figures (all bundles with anchors). Sclerenchyma all associated with vascular bundles to not all bundle-associated. The extra sclerenchyma when present, in a continuous abaxial layer. The lamina margins with fibres.
Cytology. 2n = 30.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Gymnopogoninae. 1 species.
Distribution, phytogeography, ecology. Southern tropical and South Africa.
Mesophytic; species of open habitats. In grassveld, often on sandy soil.
Rusts and smuts. Rusts Puccinia.
References, etc. Leaf anatomical: this project; photos provided by R.P. Ellis.
Illustrations. • B. biflora: 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: 13th November 2017. delta-intkey.com/grass’.