The grass genera of the world
Habit, vegetative morphology. Perennial; rhizomatous, or caespitose. Culms 15–80 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Sheath margins free. Leaf blades linear; narrow; 1–5 mm wide; flat; not pseudopetiolate; without cross venation; persistent; rolled in bud. Ligule an unfringed membrane; truncate, or not truncate (dentate or lacerate); 2 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; with capillary branchlets; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 2–5.5 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked. Hairy callus present (the hairs 1/2 to 2/3 as long as the lemma). Callus hairs present, more than 0.5 mm long.
Glumes present; two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas (about twice as long); pointed (acute); awnless; carinate; similar. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 2–3. Lemmas similar in texture to the glumes; not becoming indurated; entire; blunt; awned. Awns 1; median; dorsal; from near the top, or from well down the back; geniculate; proximally hairy. Lemmas hairy (above), or hairless (glabrous above the callus); non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.4–0.8 mm long. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea, or free from both lemma and palea; not grooved. Embryo small. Endosperm hard.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (costals more rectangular); differing markedly in wall thickness costally and intercostally (costals thicker-walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; (21–)24–33(–36) microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Prickle bases abundant. Costal zones with short-cells. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth (few); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade nodular in section to adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans (these wide, shallow). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries only); nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes large. Haploid nuclear DNA content 3.2 pg (1 species).
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Holcinae. 3–4 species.
Distribution, phytogeography, ecology. Northeast Asia.
References, etc. Leaf anatomical: studied by us - V. atropurpurea (Wahl.) Fries.
Illustrations. • V. atropurpurea, as Deschampsia: Lamson-Scribner (1897), American Grasses
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’.