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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Eremium Seberg and Linde-Laursen

Latin eremium, ‘small desert’, re ability of the type species to withstand extreme drought.

~ Elymus, Leymus

Type species: Type: E. erianthum (Phil.) Seberg and Linde-Laursen.

Habit, vegetative morphology. Perennial; caespitose. Culms 30–70 cm high; herbaceous; unbranched above. Culm nodes glabrous (brownish). Culm leaves present. Young shoots intravaginal. Leaves not basally aggregated; auriculate. Sheath margins free (?). Sheaths usually covering most of the internodes, pubescent to glabrescent. Leaf blades linear; broad to narrow; (2–)7–14.5(–20) mm wide; (in-) rolled; not pseudopetiolate; without cross venation (?); persistent. Ligule a fringed membrane (sic, ‘with a fringe of hairs’); truncate; 0.3–1 mm long. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite. Plants inbreeding.

Inflorescence. Inflorescence a single spike, or a false spike, with spikelets on contracted axes (since the spikelets are not all solitary). Spikelets solitary and paired; not secund; distichous; sessile to subsessile; imbricate.

Female-fertile spikelets. Spikelets 10–20 mm long (and 2–4 mm wide); not described re orientation; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (glabrous); the rachilla extension with incomplete florets (terminated by an empty lemma).

Glumes two; more or less equal; shorter than the spikelets to about equalling the spikelets; long relative to the adjacent lemmas (about 10–20 mm long); lateral to the rachis (? - not specified); hairless; glabrous, or scabrous (on the nerves); pointed; (linear-) subulate; awned (awnlike); similar. Lower glume 1(–3) nerved. Upper glume (1–)3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1, or 2; merely underdeveloped.

Female-fertile florets 1–3(–5). Lemmas entire (?); awned. Awns 1; median; apical (? - not described, illustration not reliably interpretable); non-geniculate; straight; hairless; much shorter than the body of the lemma to about as long as the body of the lemma (1.8–10.2 mm long). Awn bases not twisted; not flattened. Lemmas hairy (the margins densely ciliate, and sometimes hairy abaxially as well); without a germination flap; 5–7 nerved; with the nerves confluent towards the tip. Palea present; relatively long; entire to apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; ciliate. Stamens 3. Anthers 2.2–4 mm long; not penicillate; without an apically prolonged connective. Ovary apically hairy. Stigmas 2.

Fruit, embryo and seedling. Fruit adhering to lemma and/or palea, or free from both lemma and palea (? - not mentioned); medium sized (5.5 mm long); not grooved; smooth (?). Hilum long-linear (?!). Embryo small.

Cytology. Chromosome base number, x = 7. 2n = 42. 6 ploid. Haplomic genome content uncertain, but lacks S and H genomes. Chromosomes large.

Classification. Watson & Dallwitz (1994): Pooideae; Triticodae; Triticeae. Soreng et al. (2015): Pooideae; Triticodae; Triticeae; Hordeinae. 1 species (E. erianthum).

Distribution, phytogeography, ecology. Argentina.

Xerophytic; species of open habitats.

Hybrids. Possible hybridization with Elymus glaucescens.

References, etc. Morphological/taxonomic: Seberg ansd Linde-Laursen (1996).

Special comments. The morphological description is fairly inadequate (e.g. lacking information on sheath margins, spikelet orientation, fruit), and if the ‘fringed ligule’ is an error of interpretation, the difference from Elymus is limited to the long-ciliate lemmas, the genome, and geographical distribution. Fruit data wanting. Anatomical 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: 11th December 2017.’.