The grass genera of the world
Habit, vegetative morphology. Annual. Culms herbaceous. Leaves non-auriculate. Leaf blades without cross venation. Ligule an unfringed membrane; not truncate; 3–4 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate (with many slender branches at each node); open (the basal branchlets sterile); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3–3.3 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (beneath the spikelets). Hairy callus present.
Glumes two; very unequal to more or less equal; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; pointed (acute); awnless; non-carinate; similar. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets.
Female-fertile florets 2–5. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (membranous); not becoming indurated; incised; 2 lobed (bidentate); awned. Awns 1; median; from a sinus (from a deep notch); non-geniculate (fine). Lemmas hairless; glabrous; non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small (0.8 mm long); not grooved. Hilum short. Embryo small. Endosperm containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells differing markedly in wall thickness costally and intercostally (costals somewhat thicker-walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata common; 24–30–32 microns long. Subsidiaries parallel-sided, or dome-shaped (low). Guard-cells slightly overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (but often adjoining prickles). Costal silica bodies horizontally-elongated crenate/sinuous (mostly), or rounded (a few), or tall-and-narrow (a few); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size (large, round-topped). Midrib not readily distinguishable; with one bundle only. Bulliforms not present in discrete, regular adaxial groups. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (adaxial and abaxial strands only, or adaxial strands and abaxial girders). Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 1 species (N. orientalis).
Distribution, phytogeography, ecology. Western Asia.
Species of open habitats. Dry places.
References, etc. Leaf anatomical: studied by us.
Illustrations. • N. orientalis: Hook. Ic. Pl. 14 (1880)
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’.