Hordelymus (Jessen) C.O. Harz
Including Cuviera Koel.
Habit, vegetative morphology. Perennial; caespitose (from short, creeping rhizomes). Culms 40–110 cm high; herbaceous. Culm nodes hairy. Leaves auriculate. Leaf blades linear; broad, or narrow; 4–14 mm wide; flat; without cross venation; an unfringed membrane; truncate; 0.7–1 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and male-only, or hermaphrodite and sterile (the central spikelet of each triplet imperfect).
Inflorescence. Inflorescence a false spike, with spikelets on contracted axes (the spikelets in triplets on reduced axes, like Hordeum but all pedicellate); contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent (the rachis tough). Spikelets in triplets; not secund; distichous; consistently in ‘long-and-short’ combinations; unequally pedicellate in each combination. The ‘shorter’ spikelets (i.e. the central member of each triplet) male-only, or sterile. The ‘longer’ spikelets (i.e. the lateral members) hermaphrodite.
Female-fertile spikelets. Spikelets about 12 mm long; compressed dorsiventrally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension usually with incomplete florets (the upper of the two florets usually being imperfect, and with bristle beyond it).
Glumes two; more or less equal; long relative to the adjacent lemmas; joined; displaced (side by side); hairless; scabrous; subulate to not subulate (linear subulate to linear); awned (but not awnlike); carinate, or non-carinate; similar. Lower glume 3 nerved. Upper glume 3 nerved. Spikelets usually with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1; merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 1(–2) (the upper floret occasionally being also perfect). Lemmas lanceolate acuminate to the awn; similar in texture to the glumes; entire; pointed; awned. Awns 1; median; apical; non-geniculate; hairless; about as long as the body of the lemma to much longer than the body of the lemma; entered by several veins. Lemmas hairless; scabrous; non-carinate; without a germination flap; 5–7 nerved. Palea present (narrow); relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate; not toothed; not or scarcely vascularized. Stamens 3. Anthers 3–4 mm long. Ovary hairy. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit slightly adhering to lemma and/or palea; medium sized (7–8 mm long); longitudinally grooved; compressed dorsiventrally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells differing markedly in wall thickness costally and intercostally (costals thicker-walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls, or having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare. Subsidiaries low dome-shaped, or parallel-sided. Intercostal short-cells absent or very rare. Small prickles numerous. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (the few seen mostly solitary). Costal silica bodies (the feww seen) horizontally-elongated crenate/sinuous, or horizontally-elongated smooth.
Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade with the ribs very irregular in sizes. Midrib conspicuous (the girders more massive). Bulliforms present in discrete, regular adaxial groups; in simple fans. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 28 and 70. 4 and 10 ploid. Haplomic genome content H and T. Chromosomes ‘large’.
Taxonomy. Pooideae; Triticodae; Triticeae.
Distribution, ecology, phytogeography. 1 species; Europe, Western Asia. Shade species. Woodland.
Holarctic. Boreal and Tethyan. Euro-Siberian. Irano-Turanian. European.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis and Puccinia striiformis.
References, etc. Morphological/taxonomic: Löve 1984. Leaf anatomical: Metcalfe 1960; this project.
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).