The grass genera of the world
~ Elymus (Section Stenostachys)
Habit, vegetative morphology. Perennial; stoloniferous. Culms herbaceous. Culm nodes glabrous. Culm internodes hollow. Young shoots extravaginal. Leaves mostly basal; shortly auriculate, or non-auriculate (C. laevis). Leaf blades narrow; without cross venation; persistent. Ligule an unfringed membrane; truncate; 0.5 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality. Plants inbreeding; exposed-cleistogamous, or chasmogamous.
Inflorescence. Inflorescence many spikeleted; a single spike (drooping or nodding). Rachides hollowed. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; sessile; imbricate.
Female-fertile spikelets. Spikelets 9–11 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes present, or absent; when present, two (then reduced or awn-shaped); minute to relatively large (reduced to small stumps, or aristate and exceeding the rachis internodes); shorter than the adjacent lemmas; free; lateral to the rachis, or displaced (but the spikelets edgewise to the rachis); when present, subulate, or not subulate (then reduced); awned (awn-like). Lower glume 0 nerved, or 1 nerved. Upper glume 0 nerved, or 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets.
Female-fertile florets 1–2. Lemmas decidedly firmer than the glumes; awnless, or mucronate, or awned. Awns when present, 1; apical; non-geniculate; entered by one vein. Lemmas hairless; carinate to non-carinate; 9 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate; toothed, or not toothed. Stamens 3. Anthers 5–10 mm long (? - long); not penicillate. Ovary apically hairy. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea (to the palea); longitudinally grooved. Hilum long-linear (nearly as long as the caryopsis). Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (long rectangles); of similar wall thickness costally and intercostally (fairly thick walled). Mid-intercostal long-cells rectangular and fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare; 42–46.5 microns long. Subsidiaries dome-shaped. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare; silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (and some rather square and crenate).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Combined sclerenchyma girders present; forming figures.
Cytology. Chromosome base number, x = 7. 2n = 28. 4 ploid. Haplomic genome content H and S.
Classification. Watson & Dallwitz (1994): Pooideae; Triticodae; Triticeae. Soreng et al. (2015): Pooideae; Triticodae; Triticeae; Hordeinae. 2 species.
Distribution, phytogeography, ecology. New Zealand.
References, etc. Morphological/taxonomic: Löve and Connor 1982; Löve 1984. Leaf anatomical: this project.
Special comments. Fruit data wanting.
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’.