Spikelets shortly pedicellate, laterally compressed, numerous and often densely overlapping, rachilla disarticulating between the glumes and the lemma, floret 1, bisexual, rachilla often produced as a bristle beyond the floret, rarely a second floret present. Glumes subequal, 1-nerved, keeled, awnless, acute. Lemma almost as long as or longer than the glumes, 3–5-nerved, entire or toothed at the apex, firmer in texture than the glumes, with a short, often bent, dorsal awn or awnless, callus often hairy, the hairs shorter than the lemma. Palea as long as the lemma, 2-nerved and 2-keeled, thinly membranous and soft.
| | Key to the species | |
| 1 | Awn absent (the awns of some species are readily deciduous, so many spikelets should be examined) | 2 |
| Awn present | 3 |
| 2 | Leaves 2–4 cm long, mostly in tufts at the base of the plant; panicle narrow, 2–5 cm long, spikelets 2–2.5 mm long | Deyeuxia innominata |
| Leaves 4–10 cm long with many leaves on stems; panicle open to slightly contracted, 5–10 cm long; spikelets 3–3.5 mm long
Back to 1 | Deyeuxia nudiflora |
| 3 | Awn arising from lower 35% of lemma | 4 |
| Awn arising from upper 65% of lemma
Back to 1 | 5 |
| 4 | Lower glume slightly longer than upper glume or glumes equal; lemmas with 4 long teeth at apex; rachilla not usually prolonged beyond floret; panicle lobed or linear, dense | Deyeuxia quadriseta |
| Lower glume slightly shorter than upper glume; lemma teeth variable; rachilla prolonged beyond floret and may bear a second floret; panicle dense to moderately contracted
Back to 3 | Deyeuxia monticola |
| 5 | Awn arising about the middle of the lemma | 6 |
| Awn arising in top 30% of lemma (subterminal)
Back to 3 | 11 |
| 6 | Panicle less than 15 cm long | 7 |
| Panicle 15 cm or more in length
Back to 5 | 9 |
| 7 | Spikelets 3.5 mm long or less; awn less than 3 mm long; panicle somewhat contracted; slender plant | Deyeuxia rodwayi |
| Spikelets 4 mm or more in length; awn 3–4 mm long
Back to 6 | 8 |
| 8 | Spikelets 5 mm or more in length; panicle cylindrical, dense; rachilla produced as a glabrous bristle; leaves with hard tip; decumbent plant | Deyeuxia carinata |
| Spikelets c. 4–5 mm long; panicle more open; rachilla produced as a hairy bristle; leaves not hard-tipped; slender plant
Back to 7 | Deyeuxia accedens |
| 9 | Spikelets c. 3 mm long; awn 1–2 mm long, straight; panicle moderately dense, often lobed; erect plants | Deyeuxia mesathera |
| Spikelets 3.5 mm or more in length; awn 3 mm long; panicle open and spreading; robust plants
Back to 6 | 10 |
| 10 | Glumes unequal, the lower c. 75% the length of the upper; spikelets 4.5–5.5 mm long; awn longer than lemma | Deyeuxia frigida |
| Glumes equal or subequal; spikelets 3.5–4.5 mm long; awn only just exceeding the lemma
Back to 9 | Deyeuxia benthamiana |
| 11 | Awn short, less than 1 mm long and not usually projecting beyond lemma apex (if awn projects then spikelets 2 mm or less in length) | 12 |
| Awn more than 1 mm long and projecting beyond the lemma
Back to 5 | 21 |
| 12 | Lemma longer than both glumes | 13 |
| Lemma shorter than lower glume and often shorter than both glumes
Back to 11 | 15 |
| 13 | Panicle short, 2–9 cm long, narrow but not dense, with short, stiff branches; plants delicate, not usually more than 30 cm high | Deyeuxia gunniana |
| Panicle larger, 12–20 cm long, open and spreading with long branches; plants more than 30 cm high, usually erect and fairly robust
Back to 12 | 14 |
| 14 | Panicle 12–30 cm long; spikelets c. 2.5 mm long, a second floret sometimes present on prolonged rachilla (var. parviseta) | Deyeuxia parviseta |
| Panicle 20–40 cm long; spikelets c. 3.5 mm long
Back to 13 | Deyeuxia mckiei |
| 15 | Rachilla produced beyond the floret as a glabrous bristle or absent | 16 |
| Rachilla produced beyond the floret as a hairy bristle
Back to 12 | 19 |
| 16 | Spikelets 4 mm or more long; callus glabrous; plant slender | Deyeuxia angustifolia |
| Spikelets less than 4 mm long; callus hairy; erect plants
Back to 15 | 17 |
| 17 | Panicle very dense, linear; lemma truncate and minutely 4-toothed at apex | Deyeuxia imbricata |
| Panicle more open, often spreading; lemma tip obtuse, acute or toothed
Back to 16 | 18 |
| 18 | Panicle open, spreading and usually large, 12–30 cm long, nerves of lemma conspicuous; lemma not conspicuously scaberulous; rachilla bristle often absent | Deyeuxia decipiens |
| Panicle more contracted, 7–20 cm long, linear-lanceolate in outline; nerves of lemma inconspicuous; lemma scaberulous
Back to 17 | Deyeuxia contracta |
| 19 | Spikelets less than 3 mm long (var. boormanii) | Deyeuxia parviseta |
| Spikelets 3 mm or more in length
Back to 15 | 20 |
| 20 | Panicle short, 6–9 cm long; glumes subequal; lemma not obviously scaberulous | Deyeuxia microseta |
| Panicle longer, usually 9 cm or more in length; lemma distinctly scaberulous (light hairs on a darker surface); glumes unequal
Back to 19 | Deyeuxia scaberula |
| 21 | Spikelets 4 mm or more in length | 22 |
| Spikelets less than 4 mm long
Back to 11 | 24 |
| 22 | Panicle large and spreading, 20–60 cm long, with long, bare branches; robust plant | Deyeuxia acuminata |
| Panicle narrow and denser, 6–18 cm long, with spikelets towards the bases of the branches
Back to 21 | 23 |
| 23 | Awns 1–2 mm long, straight; panicle short, dense, 6–8 cm long; short grass | Deyeuxia crassiuscula |
| Awns 4–5 mm long; curved, panicle fairly dense, 8–18 cm long; erect plant
Back to 22 | Deyeuxia brachyathera |
| 24 | Panicle large, open, c. 20 cm long; lemma longer than glumes; erect plant | Deyeuxia reflexa |
| Panicle moderately open to contracted; lemma shorter than the glumes; plants erect or spreading
Back to 21 | 25 |
| 25 | Panicle 20–30 cm long, linear to lobed; awn 3–5 mm long; erect plant | Deyeuxia appressa |
| Panicle 2–6 cm long, contracted, cylindrical; awn 1.5 mm long; short alpine grass
Back to 24 | Deyeuxia affinis |
