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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.


Annual, perennial herb, rhizomes 0 to well developed. Stem: generally bent at base or erect, generally tufted. Leaf: auricles present, occasionally small, fragile; ligule membranous, truncate to obtuse; blade flat, folded, or rolled. Inflorescence: spike-like (raceme-like or panicle-like), open to dense; axis generally remaining intact with age; spikelets 1–3(7) at all or most nodes, generally ascending. Spikelet: compressed laterally, glumes generally lanceolate to awn-like, occasionally 0, awned from tip or not; florets 1–11; breaking apart above glumes and between florets; lemma generally > glumes, generally rounded, 5–7-veined, tip generally acute to awned, awn straight or curved outward; palea <, =, or > lemma or 0; anthers 3(1), 1–8 mm.
± 235 species: temperate worldwide. (Greek: covered, a reference to grain being tightly covered by palea and lemma) [Barkworth 2007 FNANM 24:283–287, 348–351, 353–369, 373–378] References to number of spikelets per node is best understood as "most, if not all" and best determined by examining nodes in middle of inflorescence. Intergeneric and interspecific hybrids, along with effects of soil moisture on plant growth, render keys even more challenging and frustrating than usual. As treated here, genus includes taxa previously assigned to Agropyron (in part), Elytrigia, Leymus, Pascopyrum, Pseudoroegneria, and Taeniatherum. Elymus ×aristatus Merr., Elymus arizonicus (Scribn. & J.G. Sm.) Gould, Elymus canadensis L., Elymus interruptus Buckley, Agropyron junceum (L.) P. Beauv. [Thinopyrum junceum (L.) Á. Löve], and Elymus pycnanthus (Godr.) Melderis [Thinopyrum pycnanthum (Godr.) Barkworth] have been reported for California, may occur sporadically, but do not appear to have become naturalized. Intergeneric hybrids involving Hordeum constitute the genus ×Elyhordeum and are cited in species descriptions. Elymus farctus (Viv.) Melderis subsp. boreo-atlanticus (Simonet & Guin.) Melderis [Elytrigia juncea (L.) Nevski subsp. boreo-atlantica (Simonet & Guin.) Hylander] naturalized, under eradication at Oceano Dunes.
Unabridged references: [Barkworth & Dewey 1985 Amer J Bot 72:767–776; Barkworth et al. 2007 FNANM 24:288–343; Carlson 2007 FNANM 24:279–282; Gould 1947 Madroño 9:120–128; Wipff 2007 FNANM 24:257, 258]

Key to Elymus

1. Annual ..... E. caput-medusae

1' Perennial herb

2. Inflorescence branched, at least at base

3. Stem 11–35 dm, 6–10 mm wide at base; blade 15–35 mm wide; spikelet 10–40 per node (inc branches) ..... E. condensatus

3' Stem 6.5–21 dm, 3.5–5 mm wide at base; blade 6–15 mm wide; spikelet 2–6 per node ..... E. ×gouldii (2)

2' Inflorescence spike-like (raceme-like), spikelets sessile or some slightly stalked (< 1 mm)

4. Plants of coastal beaches, dunes, and bluffs

5. Glumes awl-like ..... E. pacificus

5' Glumes flat, lanceolate

6. Glumes 1–2 mm wide at mid-length, keeled ..... E. ×vancouverensis

6' Glumes 3–5 mm wide at mid-length, rounded ..... E. mollis subsp. mollis

4' Plants of other habitats

7. Glumes 0 or << lowest lemma ..... E. californicus

7' Glumes 2 (on at least upper spikelets in Elymus salina), equal or unequal, but > 1/2 lowest lemma

8. Inflorescence axis breaking apart with age

9. Spikelets generally 1 per node; glumes narrowly lanceolate ..... E. scribneri

9' Spikelets 2(3) per node; glumes awn-like

10. Glumes cleft into 3–9 awn-like divisions; auricles generally present ..... E. multisetus

10' Glumes entire or 2(3)-cleft; auricles often lacking ..... E. elymoides

11. Glumes 2 on all spikelets; palea veins generally not extended as short bristles ..... var. brevifolius

11' Glumes on spikelets at lower nodes appearing to be 3, 1 a glume-like sterile floret; palea veins generally extended as short bristles

12. Glumes entire; lemma awns generally > glume awns ..... var. californicus

12' Some glumes with 2–3 awn-like divisions; lemma awns generally < glume awns ..... var. elymoides

8' Inflorescence axis remaining intact with age

13. Lemma awn generally 10–40 mm

14. Lemma awn curving outward with age

15. Stem erect at base, 30–100 cm; sagebrush steppe, woodland, < 1650 m ..... E. spicatus

15' Stem decumbent at base, generally 20–50 cm; alpine, subalpine conifer forest, > 1800 m ..... E. sierrae

14' Lemma awn straight or wavy, but not curving outward (sometimes slightly curved in Elymus glaucus)

16. Spikelets generally 2 per node ..... E. glaucus subsp. glaucus

16' Spikelets generally 1 per node

17. Anthers 4–7 mm; inflorescence internodes generally 9–27 mm ..... E. stebbinsii (2)

17' Anthers 1.2–2.5 mm; inflorescence internodes generally 7–9 mm ..... E. trachycaulus subsp. trachycaulus (2)

13' Lemma awn 0–10(15) mm

18. Glumes generally awl-like, or if lanceolate, then often inconspicuously 0–3(5)-veined, hard or tough textured, and awn-tipped or acute

19. Spikelets 2–7 per node

20. Stem node region generally densely pubescent; plants generally cespitose ..... E. cinereus

20' Stem node region glabrous; plants rhizomatous

21. Leaf blades generally 3–6 mm wide; spikelets 2(3) per node, 3–7 florets ..... E. triticoides (2)

21' Leaf blades generally 6–15 mm wide; spikelets 2–6 per node, with 6–9 florets ..... E. ×gouldii (2)

19' Spikelets generally 1 per node (sometimes 2–3 in Elymus salina)

22. Florets generally twisted so that back of lowermost lemma centered between glumes ..... E. triticoides (2)

22' Florets not twisted, back of lowermost lemma not centered between glumes

23. Plants generally cespitose (sometimes weakly rhizomed); stem 30–90 cm; cauline leaves present; glumes not curved distally ..... E. salina

23' Plants rhizomatous; stem 20–100 cm; leaves mostly basal; glumes ± curved distally ..... E. smithii

18' Glumes flat, narrowly to broadly lanceolate, strongly 3–9-veined, thin (if thickened, tip obtuse)

24. Glume tips rounded, obtuse to truncate

25. Plants rhizomatous; midvein of glume more prominent than lateral veins ..... E. hispidus

25' Plants cespitose; midvein of glume and lateral veins ± equally prominent ..... E. ponticus

24' Glume tips acute to acuminate and/or awned

26. Rhizomes present

27. Leaf blade 1–6 mm wide; lemma hairy ..... E. lanceolatus subsp. lanceolatus

27' Leaf blade 6–14 mm wide; lemma glabrous ..... E. repens

26' Rhizomes generally 0

28. Spikelets generally 2 per node ..... E. glaucus subsp. virescens

28' Spikelets generally 1 per node

29. Anthers 4–7 mm; inflorescence internodes generally 9–27 mm ..... E. stebbinsii (2)

29' Anthers 1.2–2.5 mm; inflorescence internodes generally 7–9 mm ..... E. trachycaulus subsp. trachycaulus (2)


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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