Ligule ciliate rim; blade folded in bud, flat or convolute, usually narrow and often hairy, long hairs usually present at orifice.
Inflorescence and open to spike like and contracted panicle (occasionally a raceme) with a few spikelets, white or pale at maturity. Spikelets pedicelate, disarticulating above the glumes and between the florets, 3–9 bisexual florets, often with male or sterile florets above. Glumes subequal, acute, broad-keeled, longer than the lemma, faintly 5–7-nerved (often streaked with purple), margins translucent, gaping at maturity to reveal the hairy florets. Lemmas soft to leathery, rounded on the back with a few to many hairs more or less organised into tufts, transverse rows, or rows of tufts occasionally galbrous or with the tufts reduced, or with a more or less continuous indumentum in the lower 50%; apex deeply bilobed, the lobes acute, usually terminating in slender bristles; awn arising in the sinus between the lobes reflexed or genticulate and usually twisted; callus bearded. Palea as long as or longer than the body of the lemma, 2-keeled, keels ciliate, apex entire or bifid.
Spikelets with 3–5 florets, rachilla internodes 30–50% as long as the lemmas, disarticulating above the glumes and between the lemmas. Glumes shorter or longer than the spikelet. Lemmas minutely 3-toothed, glabrous or with scattered hairs; callus blunt. Palea glabrous, keels ciliate.
Rytidosperma unarede is in Lord Howe Island and not included in the key. Key based on: Simon, B.K. & Alfonso, Y. 2011. AusGrass2, http://ausgrass2.myspecies.info/category/australian-grasses/australian-grasses/rytidosperma, 10 August 2012. key reconfigured for NSW species by Louisa Murray
Taxa not yet included in identification key
Rytidosperma unarede
| | Key to the species | |
| 1 | Callus up to twice the length of the spikelet axis internode | 2 |
| Callus greater than twice the length of the spikelet axis internode | 10 |
| 2 | Hairs on the lemma forming a continuous indumentum, sometimes with tufts on the upper margin; leaves not disarticulating | 3 |
| Hairs on the lemma in two untidy rows, most of lemma surface glabrous and shiny, leaves often disarticulating from sheath
Back to 1 | 6 |
| 3 | Marginal hair tufts absent; anthers red | Rytidosperma pallidum |
| Marginal hair tufts present; anther yellow to orange
Back to 2 | 4 |
| 4 | Lateral lobes shortly awned | Rytidosperma longifolium |
| Lateral lobes not or minutely awned
Back to 3 | 5 |
| 5 | Leaf-sheaths glabrous | Rytidosperma semiannulare |
| Leaf-sheaths distinctly pilose
Back to 4 | Rytidosperma gracile |
| 6 | Spikelet axis internode 1/3–1/2 lemma length | 7 |
| Spikelet axis internode up to 1/4 lemma length
Back to 2 | 8 |
| 7 | Lemma c. 2.5 mm long, ±hairy | Rytidosperma pumilum |
| Lemma c. 2 mm long, glabrous
Back to 6 | Rytidosperma australe |
| 8 | Lateral lobes distinctly longer than the body of lemma | Rytidosperma nudiflorum |
| Lateral lobes shorter than or only slightly longer than body of lemma
Back to 6 | 9 |
| 9 | Leaf blades tightly inrolled, florets shorter than glumes except for the exserted awns; central awn well separated from lateral lobes | Rytidosperma nivicola |
| 9 | *Leaf blades flat at base, becoming folded or slightly inrolled; florets exserted from glumes; central awn scarcely separated from lateral lobes | Rytidosperma vickeryae |
| 10 | Lemma with hairs only in distinct transverse rows of tufts on back | 11 |
| Lemma with hairs scattered uniformly over back instead of or as well as hairs in tufts
Back to 1 | 25 |
| 11 | Lemma with a complete transverse row of hair-tufts just below sinus | 12 |
| Lemma with marginal and/or dorsal tufts of hair below sinus sometimes forming an interrupted row
Back to 10 | 23 |
| 12 | Lemma without a row of hair-tufts above callus | Rytidosperma laeve |
| Lemma with a row of hair-tufts above callus
Back to 11 | 13 |
| 13 | Outer margins of lateral lobes with auricles | Rytidosperma auriculatum |
| Outer margins of lateral lobes without auricles
Back to 12 | 14 |
| 14 | Body of lemma golden brown at maturity | Rytidosperma duttonianum |
| Body of lemma pale at maturity
Back to 13 | 15 |
| 15 | Body of lemma 1.25–3 mm long | 16 |
| Body of lemma 3 mm or more long
Back to 14 | 18 |
| 16 | Lateral lobes less than 6 mm long | Rytidosperma setaceum |
| Lateral lobes 6–10 mm long
Back to 15 | 17 |
| 17 | Setae of lateral lobes 2–4 mm long | Rytidosperma monticola |
| Setae of lateral lobes 4–6 mm long
Back to 16 | Rytidosperma setaceum |
| 18 | Setae much shorter than flat portion of lateral lobes | 19 |
| Setae ± as long as flat portion of lateral lobes
Back to 15 | 21 |
| 19 | Palea 7–8mm long, ±equaling flat part of lemma lateral lobes | Rytidosperma indutum |
| Palea to 6mm long, shorter than flat part of lemma lateral lobes
Back to 18 | 20 |
| 20 | Palea broad, 1–3 times as long as wide | Rytidosperma oreophilum |
| Palea narrow, 3–5 times as long as wide
Back to 19 | Rytidosperma tenuius |
| 21 | Palea up to 3 mm wide | Rytidosperma erianthum |
| Palea less than 2 mm wide
Back to 18 | 22 |
| 22 | Leaves 5–10 cm long, thick and rigid | Rytidosperma alpicola |
| Leaves 10–30 cm long, not thick and rigid
Back to 21 | Rytidosperma caespitosum |
| 23 | Inflorescence 3–5 cm long | Rytidosperma pilosum |
| Inflorescence 5–15 cm long
Back to 11 | 24 |
| 24 | Spikelets 4–6-flowered | Rytidosperma penicillatum |
| Spikelets 7–10-flowered
Back to 23 | Rytidosperma racemosum |
| 25 | Lateral lobes shorter than body of lemma | Rytidosperma carphoides |
| Lateral lobes equal to or longer than body of lemma
Back to 10 | 26 |
| 26 | Lateral lobes 2–3 times as long as body of lemma | Rytidosperma monticola |
| Lateral lobes less than twice as long as body of lemma or latter at least 3mm long
Back to 25 | 27 |
| 27 | Lemma hairs uniformly short (about 0.5 mm long) except for those directly below sinus | 28 |
| Lemma hairs grading from 1mm long at base to 5 mm long at apex
Back to 26 | 29 |
| 28 | Body of lemma less than 3 mm long | Rytidosperma setaceum |
| Body of lemma at least 3 mm long
Back to 27 | Rytidosperma alpicola |
| 29 | Central awn reflexed or loosely twisted at base | 30 |
| Central awn strongly twisted at base
Back to 27 | 31 |
| 30 | Palea broadly obovate, obtuse; body of lemma 4–6 mm long | Rytidosperma richardsonii |
| Palea lanceolate-elliptic, acute; body of lemma 3–3.5 mm long
Back to 29 | Rytidosperma bipartitum |
| 31 | Body of lemma 3–4 mm long; palea less than 5 mm long | Rytidosperma fulvum |
| Body of lemma 4–5.5 mm long; palea 6–8 mm long
Back to 29 | Rytidosperma indutum |
