Culms erect or prostrate, slender, unbranched or branched, especially near the base, if so vertical or oblique rhizomes may be formed. Ligule membranous, to 10 mm long or reduced to a short rim with hairs; blade folded in bud, flat, involute or folded, often narrow or bristle-like, tip often blunt and keeled.
Inflorescence an open or contracted panicle. Spikelets solitary, 3–12 mm long, pedicellate, laterally compressed, rachilla disarticulating above the glumes and between the lemmas, 2–several-flowered, the uppermost florets reduced. Glumes acute, keeled, unequal, the lower 1-nerved, the upper 3-nerved, usually shorter than adjacent lemmas. Lemmas keeled, acute, rarely obtuse, 5-nerved, ± hairy on the back towards the base, awnless, callus short often with loose, woolly hairs (‘web’); palea slightly shorter than the lemmas, scabrous or ciliate on the two keels.
Key after Vickery (1970). P. pratensis is planted as a pasture and lawn species; many species are major components of montane and alpine grasslands; a few species are regarded as weeds.
| | Key to the species | |
| 1 | Robust perennials growing on coastal foredunes; leaves erect, stiff; inflorescences rarely exserted above leaves; lemmas glabrous (in NSW), apiculate | Poa billardierei |
| Annuals or perennials but not growing on coastal foredunes; if leaves stiff and erect then alpine or subalpine species; inflorescences usually exserted beyond leaves; lemmas never apiculate and hairy or glabrous | 2 |
| 2 | Small annuals with soft leaves, 2–30 cm tall; ligule soft and thin, glabrous; web on lemma absent | 3 |
| Perennials rarely < 10 cm tall unless grazed or mown; ligule soft or firm, glabrous or hairy; with or without web on lemma
Back to 1 | 5 |
| 3 | Panicle narrow with erect spikelets appressed to the branches; lemmas 3.5–4.5 mm long | Poa fax |
| Panicle triangular to ovate with slender, spreading branches; spikelets spreading at maturity; lemmas 2–4 mm long
Back to 2 | 4 |
| 4 | Anthers 0.2–0.5 mm long; lemmas 2–2.5 mm long, separate | Poa infirma |
| Anthers 0.7–1.3 mm long; lemmas 2.5–4 mm long, overlapping
Back to 3 | Poa annua |
| 5 | Plants with pear-shaped bulbs due to enlargement of the inner leaf sheaths at the base of the plant; web on lemma copious | Poa bulbosa |
| Plants not bulbous or thickened at the base; with or without web on lemmas
Back to 2 | 6 |
| 6 | Internodes of the culm compressed and 2-sided; leaves folded; lemmas 2–3 mm long | Poa compressa |
| Internodes of the culm round or only slightly compressed, rarely strongly compressed (in P. fordeana culms may be strongly compressed, the latter has flat leaves and lemma 3.5–5 mm long)
Back to 5 | 7 |
| 7 | Spikelets plump; lemmas broadly ovate; palea ovate; keels densely ciliate with hairs in several rows; panicle narrow with rather few spikelets | Poa saxicola |
| Spikelets laterally compressed; lemmas not broadly ovate; paleas ± ciliate on keels but hairs in one row only; panicle ± narrow, but if narrow then numerous spikelets
Back to 6 | 8 |
| 8 | Leaf-blades smooth or scabrous on the abaxial surface but not obviously hairy; lemmas pubescent over the lower back or hairy on the nerves and keel only | 9 |
| Leaf-blades hairy on abaxial surface, the leaf-sheath often hairy; lemmas usually pubescent over the lower back (nerves, keel and internerves)
Back to 7 | 32 |
| 9 | Ligule a thin, almost translucent membrane, not scabrous and without obvious hairs on the back, nor ciliate, 2 mm long or more (rarely less) | 10 |
| Ligule a firm (not translucent) membrane, scabrous or puberulous on the back and/or ciliate at the apex or reduced to a rim of hairs, 0.1–2 mm long (-3 in P. costiniana)
Back to 8 | 14 |
| 10 | Tufted perennnials without rhizomes or stolons; leaf-blades 4–15 mm wide, broad and flat; lemma nerves raised above the surface; tall plant of rainforest margins with culms to 1.5 m tall | Poa queenslandica |
| Tufted perennials also producing stolons or rhizomes; leaf-blades narrower, not >6 mm wide; lemma nerves ± prominent; plants usually not as tall as previous species
Back to 9 | 11 |
| 11 | Plants with leafy stolons; ligule acute to acuminate, 4–10 mm long | 12 |
| Plants not stoloniferous but with rhizomes; ligule obtuse to truncate and not usually >5 mm long
Back to 10 | 13 |
| 12 | Loosely tufted perennials with extravaginal innovations and creeping leafy stolon; blades flat or folded, finely scabrous to subsmooth; ligule 4–10 mm long; lemma rather distictly dorsally curved | Poa trivialis |
| Caespitose perennials with mostly intravaginal innovations; blades inrolled, capillary, loosely hispid to scabrous; ligule 1–4.5 mm long; lemma not distinctly dorsally curved
Back to 11 | Poa hookeri |
| 13 | Spikelets 8–10 mm long and strongly compressed; peduncle compressed and branches widely spreading at maturity; lemmas woolly hairy over lower back; leaf-sheaths of lower leaves closed at the base | Poa fordeana |
| Spikelets 2.5–6 mm long and not as strongly compressed; lemmas hairy on the keel and marginal nerves and not between (the internerves); web prominent; leaf sheaths open
Back to 11 | Poa pratensis |
| 14 | Leaf-blades broad or narrow, flat or folded and V-shaped in cross-section, the edges sometimes inrolled on drying | 15 |
| Leaf-blades (excluding flag-leaf) narrow, closely folded or tightly rolled so that the leaves are bristle-like or angular to round in cross-section
Back to 9 | 22 |
| 15 | Stems often leafy, branching from aerial nodes to form leafy shoots; plants tufted and/or stoloniferous | 16 |
| Leaves mostly basal and culms usually unbranched; plants tufted or rhizomatous
Back to 14 | 17 |
| 16 | Leaf-blades firm to rigid, 1–5 mm wide when opened out; plants robust and erect (stems to 1.2 m tall); ligule often ciliolate; panicle often rather contracted with many spikelets; lemmas pubescent on lower back with longer hairs on nerves and keel | Poa affinis |
| Leaf-blades much softer, 1–1.5 mm wide when opened out, almost thread-like in some plants; tufted and stoloniferous plants; ligule not ciliolate; panicle open with few spikelets on long, slender branches; lemma pubescent on the lower back (including nerves) to glabrous
Back to 15 | Poa tenera |
| 17 | Plants usually with horizontal rhizomes that produce new shoots outside the limits of the parent tussock | 18 |
| Plants tufted, not producing rhizomes outside the parent tussock (rhizomes may develop in a vertical or oblique direction in response to environmental changes)
Back to 15 | 20 |
| 18 | Lower leaf-sheaths usually with a purplish colouration; lemmas usually pubescent on the internerves, nerves and keel; leaf-blades rigid | Poa ensiformis |
| Lower leaf-sheaths not purplish, lemmas glabrous on the internerves but hairy on the nerves and keel; leaf-blades ± rigid
Back to 17 | 19 |
| 19 | Leaf-blades rigid; rhizomes short, thick, with firm, obtuse scales; spikelets strongly compressed | Poa cheelii |
| Leaf-blades soft to moderately firm, rhizomes slender with firm, pointed scales; spikelets not strongly compressed
Back to 18 | Poa pratensis |
| 20 | Panicle usually contracted, ± linear, if with spreading branches then at least some of them short and with spikelets almost to their bases; spikelets usually large (lemmas 3–6 mm long); leaf-blades smooth on the abaxial surface; plant of coastal foreshores and estuaries | Poa poiformis |
| Panicle spreading at maturity and branches bare of spikelets in the lower part; spikelets smaller, 2.5–4 mm long; leaf-blades scabrous on abaxial surface; not usually on coastal foreshores
Back to 17 | 21 |
| 21 | Leaf-blades 1–3.5 mm wide, a dull green or greyish-green in colour; peduncle usually round in cross-section; the common large tussock grass of moist areas below 1500 m altutude | Poa labillardierei |
| Leaf-blades 3–8 mm wide, usually light-green in colour when alive, peduncle usually compressed, tussock grass of wet areas of elevations c. 1300 metres
Back to 20 | Poa helmsii |
| 22 | Culms branched with aerial shoots or plants stoloniferous and/or trailing; leaves fine and soft, c. 0.5 mm or less in diameter | 23 |
| Tussocks rarely producing aerial shoots and without stolons; leaves variable in width and texture
Back to 14 | 24 |
| 23 | Tussocks lax; web on lemma often absent; lemmas pubescent or glabrous on lower back; leaves not usually bluish in colour | Poa tenera |
| Tussocks more erect; web usually present, lemmas pubescent on lower back; leaves usually bluish
Back to 22 | Poa sieberiana |
| 24 | Panicle contracted and often linear, if with spreading branches then some short, with spikelets almost to their bases; lemmas relatively large, usually 4–5 mm long; grows on coastal foreshores | Poa poiformis |
| Panicle spreading at maturity, if contracted then the lower branches bare at their bases; lemma length variable; not usually on coastal foreshores
Back to 22 | 25 |
| 25 | Hairs on the lower back of lemmas concentrated along the keel and lateral nerves, the internerves usually glabrous but a few scattered hairs may be present; palea scabrous towards the apex, not usually ciliolate | 26 |
| Lower back of lemmas hairy all over, pubescent on the internerves and often with longer and/or denser hairs on the keel and lateral nerves; palea scabrous above and usually ciliolate below
Back to 24 | 29 |
| 26 | Leaf-blades smooth on outer surface and rigid; tussocks not usually large and grows in wet places of alpine and subalpine regions | Poa costiniana |
| Leaf-blades very lightly to distinctly scabrous on the outer surface and not particularly rigid; habitat variable
Back to 25 | 27 |
| 27 | Robust grass, forming large tussocks with leaves 0.5 mm or more in diam. Common in wet places | Poa labillardierei |
| Plants less robust, forming small tussocks with fine leaves <0.5 mm diam.; not very common
Back to 26 | 28 |
| 28 | Glumes narrow and lemmas small, the latter 2–3.5 mm long; leaves relatively soft | Poa meionectes |
| Glumes broader and lemmas longer, the latter 3–4 mm long; leaves more rigid
Back to 27 | Poa clivicola |
| 29 | Leaf-blades smooth to touch on outer surface | 30 |
| Leaf-blades moderately to distinctly scabrous or smooth on outer surface, if smooth then leaves dull green and lemmas small, 1.8–3 mm long
Back to 25 | 31 |
| 30 | Leaf-blades soft and bright green when alive; lemmas 2.3–5 mm long | Poa hiemata |
| Leaf-blades rigid, often bluish-green; leaf-sheaths usually purplish at the base; lemmas 3–3.5 mm long
Back to 29 | Poa fawcettiae |
| 31 | Leaf-blades bluish in colour, rigid, with purplish leaf-sheaths; spikelets often purplish; lemmas 2.5–3.5 mm long | Poa phillipsiana |
| Leaf-blades ± bluish, less rigid, bases of leaf-sheaths and spikelets not usually purplish; lemmas 1.8–3 mm long
Back to 29 | Poa sieberiana |
| 32 | Lemmas 3–4 mm long; leaf-blades with dense, soft, short hairs of equal length; leaf-sheaths purplish at base | Poa petrophila |
| Lemmas usually <3 mm long; leaves with sparse, stiff hairs, or hairs of unequal length; leaf-sheaths not purplish
Back to 8 | 33 |
| 33 | Leaves narrow with sparse, stiff hairs, extravaginal shoots often present | Poa sieberiana |
| Leaves not as narrow, densely hairy with hairs of two lengths, or surface distinctly scabrous between rows of hairs; extravaginal shoots absent
Back to 32 | Poa induta |
