The grass genera of the world
~ Elymus, Elytrigia
Habit, vegetative morphology. Perennial (with stout, firm glabrous culms); caespitose. Culms 30–100 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Young shoots intravaginal. The shoots not aromatic. Leaves not basally aggregated. Leaf blades narrow (glaucous, stiff, with thick veins); rolled; not pseudopetiolate; without cross venation; persistent. Ligule an unfringed membrane; truncate. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single spike (the spikelets appressed early, but becoming divaricate). Rachides flattened (against the spikelets). Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent (usually), or disarticulating; when disarticulating, disarticulating at the joints (the spikelet falling with the internode above). Spikelets solitary; not secund; distichous; sessile.
Female-fertile spikelets. Spikelets compressed laterally; disarticulating above the glumes, or falling with the glumes; not disarticulating between the florets to disarticulating between the florets (?). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent. Callus short; pointed (glabrous).
Glumes two; more or less equal (or slightly unequal); shorter than the spikelets; shorter than the adjacent lemmas; lateral to the rachis; not pointed (obtuse to truncate); not subulate; awnless; non-carinate; similar (oblong, leathery to hardened). Lower glume 3–9 nerved. Upper glume 3–9 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 3–12 (few to many). Lemmas entire; blunt; awnless; sparsely hairy, or hairless; non-carinate; without a germination flap; 5 nerved; with the nerves confluent towards the tip. Palea present; relatively long (slightly shorter than the lemma); awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate; not toothed. Stamens 3. Anthers 4–10 mm long. Ovary apically hairy. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea; medium sized; longitudinally grooved; compressed dorsiventrally; with hairs confined to a terminal tuft. Hilum long-linear. Embryo small. Endosperm containing only simple starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation lacking (for the most part). Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (indistinguishable in form, fairly thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata absent or very rare (in the material of L. elongatum seen), or common (L. elongatum according to Metcalfe). Subsidiaries low dome-shaped (recorded by Metcalfe). Intercostal short-cells common; in cork/silica-cell pairs; silicified. Crown cells present (common, fairly small). Costal short-cells predominantly paired (some solitary). Costal silica bodies saddle shaped, or tall-and-narrow, or crescentic, or rounded (integrading with the other forms); not sharp-pointed.
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 very irregular in sizes (the large ribs varying in shape, and the blade asymmetric in section). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (the groups very small, in the furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the main bundles - the minor bundles with abaxial girders only); forming figures (the main bundles with massive Is). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14, 28, 56, and 70. 2, 4, 8, and 10 ploid. Haplomic genome content E. Haploid nuclear DNA content 5.6 pg (1 species). Mean diploid 2c DNA value 11.2 pg (1 species).
Classification. Watson & Dallwitz (1994): Pooideae; Triticodae; Triticeae. Soreng et al. (2015): cf. Pooideae (as a synonym); Triticodae; Triticeae; Hordeinae. 11 species.
Distribution, phytogeography, ecology. Mediterranean to Iran.
Commonly adventive. Xerophytic; species of open habitats; halophytic. Coastal sands.
Hybrids. Intergeneric hybrids with Elytigia, Leymus, Sitanion, Triticum.
References, etc. Morphological/taxonomic: Löve 1984. Leaf anatomical: this project.
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’.