Deyeuxia Clarion ex P. Beauv.
After Nicolas Deyeux (1753–1837) Professor of Pharmacy Medicine, Paris.
Including Sclerodeyeuxia (Stapf) Pilger
Sometimes referred to Calamagrostis. See also Agrostis, Dichelachne
Excluding D. uncinioides = Ancistragrostis, Aniselytron, Stilpnophleum
Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Leaves mostly basal, or not basally aggregated; non-auriculate. Leaf blades narrow; without cross venation; persistent; an unfringed membrane; truncate; 0.5–2 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality. Plants inbreeding.
Inflorescence. Inflorescence paniculate; open, or contracted; when contracted, spicate to more or less irregular; without capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 1–8 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret, or terminated by a female-fertile floret (rarely); hairy, or hairless; the rachilla extension when present, naked. Hairy callus present (the hairs sometimes 0.5 mm or more long, but shorter than the lemma), or absent.
Glumes two; very unequal, or more or less equal; about equalling the spikelets to exceeding the spikelets; long relative to the adjacent lemmas (the lemma usually at least 3/4 as long, by contrast with Calamagrostis, but only about half as long in D. drummondii); pointed, or not pointed; awnless; carinate; similar. Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1(–2). Lemmas decidedly firmer than the glumes (the main, equivocal distinction from Agrostis); not becoming indurated; incised; usually minutely 2–4 lobed; not deeply cleft (toothed); nearly always awned (rarely only mucronate). Awns when present, 1; dorsal; from near the top, or from well down the back; non-geniculate, or geniculate; much shorter than the body of the lemma to about as long as the body of the lemma, or much longer than the body of the lemma; entered by one vein; deciduous, or persistent. Lemmas hairless; non-carinate; 4–5 nerved. Palea present; relatively long, or conspicuous but relatively short, or very reduced; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small; longitudinally grooved; with hairs confined to a terminal tuft. Hilum short. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (elongated); differing markedly in wall thickness costally and intercostally (the costals thicker walled). Mid-intercostal long-cells rectangular to fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common. Subsidiaries low dome-shaped, or parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare; not paired; not silicified. Costal short-cells conspicuously in long rows, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded.
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. Midrib not readily distinguishable; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (irregularly grouped in the furrows, of small cells - cf. Ammophila). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 28.
Taxonomy. Pooideae; Poodae; Aveneae. Bent grasses.
Distribution, ecology, phytogeography. 42 species; temperate.
Holarctic, Paleotropical, Neotropical, Australian, and Antarctic. Tethyan. Indomalesian. Irano-Turanian. Indian, Indo-Chinese, Malesian, and Papuan. Pampas. North and East Australian and South-West Australian. New Zealand and Patagonian. Temperate and South-Eastern Australian.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia hordei, and Puccinia recondita. Smuts from Ustilaginaceae. Ustilaginaceae — Ustilago.
References, etc. Morphological/taxonomic: Vickery 1940. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • General aspect, spikelets and lemmas. • Inflorescence detail. • Abaxial epidermis of leaf blade. Deyeuxia quadriseta.
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
