The grass genera of the world
Habit, vegetative morphology. Annual; caespitose. Culms 26 cm high; herbaceous; unbranched above. Plants unarmed. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 0.5–2 mm wide (?-to 2 mm wide, the margins cartilaginous, with tubercular hairs marginally and abaxially); not setaceous; flat; without cross venation; persistent. Ligule a fringed membrane. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence few spikeleted; very sparse, a single raceme (with long, capillary pedicels), or paniculate (the lower branches sometimes branched again); open; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate (the long pedicels glandular).
Female-fertile spikelets. Spikelets 5–9 mm long (red tinged, reminiscent of Briza, but not pendulous); suborbicular; compressed laterally (but plump); disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; very hairy; the rachilla extension with incomplete florets. Hairy callus present.
Glumes two; more or less equal; shorter than the spikelets; long relative to the adjacent lemmas; free; hairless; glabrous; pointed; awned (attenuate into short awns); carinate; similar (thinly membranous, ovate acuminate). 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.
Female-fertile florets 4–8. Lemmas fan-shaped, very broad above - much broader than long; similar in texture to the glumes (membranous); not becoming indurated; incised; not deeply cleft (emarginate); awned. Awns 1; median; from a sinus; non-geniculate; hairless (scabrid); about as long as the body of the lemma to much longer than the body of the lemma; entered by one vein. Lemmas hairy (along the nerves); carinate; without a germination flap; 3 nerved. Palea present; relatively long (bent sharply inwards over the pistil, with hair tufts at the elbows); entire; awnless, without apical setae; not indurated (membranous); 2-nerved; 2-keeled. Palea keels hairy. Lodicules present; 2; free; small, rather thin (not the usual cuneate type); glabrous. Stamens 3; with free filaments (fairly long). Anthers very short; 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 1.5 mm long); longitudinally grooved; compressed laterally. Hilum short. Pericarp free. Embryo large; slightly waisted.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (costals longer and narrower); of similar wall thickness costally and intercostally (walls of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical to elongated; clearly two-celled; chloridoid-type; (30–)31.5–36(–39) microns long; (12.6–)14.4–15 microns wide at the septum. Microhair total length/width at septum 2–2.7. Microhair apical cells (9–)9.6–10.5(–12) microns long. Microhair apical cell/total length ratio 0.27–0.36. Stomata common; 24–30 microns long. Subsidiaries mostly dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common (fairly); not paired (solitary); not silicified. Cushion-based macrohairs present. Costal short-cells conspicuously in long rows (the short-cells rather long in some files). Costal silica bodies saddle shaped (predominating, save over the midrib and blade margins), or rounded (common over some veins), or oryzoid (a few), or panicoid-type; including a few short dumb-bell shaped, or cross shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS+. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib 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 bundles); forming figures (all the large bundles anchor-shaped). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Pappophorinae. 1 species (N. barbata).
Distribution, phytogeography, ecology. Brazil.
Mesophytic; species of open habitats. Disturbed ground.
References, etc. Leaf anatomical: studied by us.
Illustrations. • N. barbata (as Briza: Fl. Brasiliensis 2 (1878. • Abaxial epidermis of leaf blade (N. barbata)
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’.