The grass genera of the world
Including Fluminia Fries
Habit, vegetative morphology. Perennial; rhizomatous (with succulent rhizomes). Culms 70–200 cm high. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; broad, or narrow; 4–12 mm wide; flat; not pseudopetiolate; without cross venation. Ligule an unfringed membrane; truncate; 3–10 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open (to 30 cm long); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 7–11 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked. Hairy callus present. Callus short; pointed.
Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; hairless; pointed (acute to acuminate); awnless; non-carinate; similar. Lower glume 1–5 nerved. Upper glume 3–7 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 3–4. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (somewhat leathery); not becoming indurated; indistinctly incised; 3 lobed (or lacerate); not deeply cleft; awnless, or mucronate; hairless (save for the villous callus); non-carinate; without a germination flap; 5–9 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 2–4 mm long. Ovary apically apically hairy. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small (about 2 mm long); compressed dorsiventrally. Hilum long-linear. Embryo small (but nearly 1/3 of the grain length). Endosperm hard; without lipid; 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 similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata common; 33–39 microns long. Subsidiaries parallel-sided and dome-shaped. Guard-cells overlapped by the interstomatals, or overlapping to flush with the interstomatals. Intercostal short-cells in cork/silica-cell pairs; silicified. Costal short-cells predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (short), or rounded and crescentic (or more or less rectangular); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Bulliforms present in discrete, regular adaxial groups (at the bases of the furrows); in simple fans. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 28. 4 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Scolochloinae. 2 species.
Distribution, phytogeography, ecology. North temperate.
Helophytic, or mesophytic. Lakes, rivers, wet meadows.
Economic aspects. Important native pasture species: S. festucacea.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia coronata and Puccinia recondita. Smuts from Ustilaginaceae. Ustilaginaceae Ustilago.
References, etc. Leaf anatomical: this project; Metcalfe 1960.
Illustrations. • S. dura: Nicora & Rúgolo de Agrasar (1987)
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’.