| 1 |
Annual or sometimes perennial, keels of palea with flexuous, curved or crispate hairs along their whole length (or almost so) |
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(2) |
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Perennial or rarely annual; keels of palea scabrid or prickly, if hairy then only in the lower half |
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(5) |
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| 2 (1) |
Lower panicle-branches erecto-patent after anthesis; spikelets with rather distant florets; anthers 0.2-0.5 mm long, scarcely longer than wide |
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Poa infirma |
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Lower panicle-branches spreading or deflexed after anthesis; spikelets with crowded florets; anthers 0.6-2mm long, at least twice as long as wide |
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(3) |
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| 3 (2) |
Spikelets not crowded towards the ends of the panicle-branches; anthers 0.6-0.8 (-1) mm long, 2-3 times as long as wide |
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(4) |
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Spikelets crowded towards the ends of the panicle-branches; anthers usually 1.3-2 mm long, 5-8 times as long as wide |
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Poa supina |
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| 4 (3) |
Lemma with copious wool at the base |
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Poa nepalensis |
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Lemma without any wool at the base |
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Poa annua |
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| 5 (1) |
Stem with a bulbous swelling at the base formed from the hardened remains of old leaf-sheaths |
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(6) |
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Stem not bulbous at the base, but sometimes thickened with the scarious or fibrous (not hardened) remains of old leaf-sheaths |
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(8) |
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| 6 (5) |
Lemma entirely hairless though often scabrid |
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Poa bactriana |
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Lemma ciliate, or at least thinly hairy, on the keel and marginal nerves |
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(7) |
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| 7 (6) |
Lemma with wool at the base, this usually copious; lemmas 2.5-3.5mm long; anthers 1-1.5mm long (or spikelets usually proliferating and these characters not visible) |
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Poa bulbosa |
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Lemma without wool at the base (or sometimes just 1 or 2 strands); lemmas 3.5-5mm long; anthers 1.5-2.5mm long (spikelets rarely proliferating in our area) |
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Poa sinaica |
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| 8 (5) |
Robust perennial up to 120 cm high; lemma entirely glabrous; panicle narrow; species only in cultivation |
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Poa ampla |
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Plant not as above; if lemma glabrous then plant not over 40cm high and panicle ovate or pyramidal; native wild specie |
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(9) |
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| 9 (8) |
Lemma hairy on the surface between the nerves (this may be extremely sparse) or sometimes only shortly asperulous |
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(10) |
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Lemma glabrous on the surface between the nerves although the keel and marginal nerves are usually ciliate below |
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(17) |
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| 10 (9) |
Palea-keels ciliate below, scabrid above |
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(11) |
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Palea-keels scabrid throughout their length. |
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(14) |
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| 11 (10) |
Stoloniferous plant with culms often ascending from a procumbent base which sometimes roots from the lower nodes; panicle loose, 12-25cm long |
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Poa stapfiana |
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Tufted plants without stolons; culms not rooting from the lower nodes; panicle lax or dense |
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(12) |
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| 12 (11) |
Spikelets, when young, broadly ovate; leaf-blades 4-12cm long, 2-5mm wide; panicle compact or spreading, 3-7cm long; culms clothed at the base with the fibrous remains of old leaf-sheaths |
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Poa alpina |
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Spikelets, when young, elliptic or lanceolate; leaf-blades up to 6cm long and 1.5mm wide; panicle contracted, 0.5-5cm long; culms clothed at the base with the scarious remains of old leaf-sheaths |
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(13) |
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| 13 (12) |
Dwarf plants up to 10(-15)cm high; wool present at the base of the lower lemmas; leaf blades up to 2cm long |
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Poa koelzii |
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Taller plants up to 30 cm high; wool absent or extremely sparse; leaf-blades 2-6cm long |
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Poa lahulensis |
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| 14 (10) |
Tufted plants with rhizomes; panicle contracted, spike-like; lemma asperulous all over the back; palea-keels with prickles below and teeth above |
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Poa tibetica |
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Tufted plants without rhizomes, though sometimes with stolons; panicle lax or effuse, not spike-like; lemmas shortly hairy or with a felty pubescence between the nerves below; palea-keels evenly scabrid or prickly |
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(15) |
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| 15 (14) |
Lower glume subulate-acuminate in side-view, 1-nerved; lemmas obtuse; plant stoloni¬ferous |
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Poa polycolea |
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Lower glume elliptic or oblong, 1-3-nerved; lemmas acute or obtuse; plant tufted, the culms sometimes decumbent at the base and rooting from the lower nodes, but the plant not other-wise spreading by stolons |
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(16) |
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| 16 (15) |
Slender grass; lemmas very blunt, scabrid on the back and with either a few short hairs or a felty pubescence between the nerves below; spikelets ovate-elliptic, up to 5.5mm long |
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Poa pagophila |
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Robust grass; lemmas acute, gland-pitted on the back and with short, rather coarse hairs below; spikelets 7-8mm long, the florets eventually widely diverging |
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Poa falconeri |
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| 17 (9) |
Palea-keels ciliate below, scabrid above |
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(18) |
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Palea-keels scabrid ± throughout their length |
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(19) |
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| 18 (17) |
Base of the lemma without any wool |
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Poa sikkimensis |
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Base of the lemma with copious wool |
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Poa stewartiana |
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| 19 (17) |
Plants rhizomatous |
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(20) |
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Plants not rhizomatous |
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(23) |
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| 20 (19) |
Lemmas very broad, not strongly keeled on the back, rounded and broadly hyaline at the tip |
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Poa calliopsis |
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Lemmas strongly keeled on the back, acute or narrowly obtuse at the tip, narrowly hyaline at most |
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(21) |
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| 21 (20) |
Uppermost node in the median third of the culm or above; plant loosely or densely tufted from a slender rhizome |
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(22) |
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Uppermost node in the basal third of the culm; plant densely tufted from a short thick rhizome |
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Poa versicolor subsp. araratica |
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| 22 (21) |
Panicle narrow, few-spiculate, the branches 2-3 at the lower nodes; ligule 1.5-3mm long (if ligule not more than 1 mm see 21. P. nemoralis) |
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Poa sterilis |
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Panicle lanceolate to ovate, with many spikelets, often rather dense, with 3-5 branches at the lower nodes; ligule 1-3mm long (if ligule 3.5-10 mm long see 20. P. trivialis) |
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Poa pratensis |
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| 23 (19) |
Anthers 0.6-0.75 mm long |
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Poa setulosa |
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Anthers 1.3-2.5mm long |
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(24) |
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| 24 (23) |
Ligule pointed, 3.5-10 mm long |
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Poa trivialis |
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Ligule pointed or blunt, not more than 3mm long |
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(25) |
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| 25 (24) |
Ligule very short, scarcely exceeding 1mm in length |
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(26) |
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Ligule longer, 1-3 mm long |
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(27) |
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| 26 (25) |
Anthers 1.3-2mm long; lower glume 3-nerved; panicle-branches scaberulous, 2-5 at the lower nodes |
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Poa nemoralis |
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Anthers 1.8-2.5 mm long; lower glume 1-nerved; panicle-branches smooth, paired at the lower nodes |
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Poa aitchisonii |
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| 27 (25) |
Tall plant, usually 40-120cm high; spikelets ovate or oblong, not becoming wedge-shaped; panicle ample, 10-20(-30)cm long, with branches in distant clusters of 3-6 at a node |
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Poa palustris |
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Smaller plants, but sometimes reaching 40cm in height; spikelets often becoming wedge-shaped; panicle not ample, either short (2-10cm long) and dense or longer (7-15cm long) but with relatively few spikelets |
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(28) |
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| 28 (27) |
Plant stoloniferous, the culms erect or geniculately ascending from a creeping base; panicle very loose and spreading |
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Poa polycolea |
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Plant tufted, not stoloniferous, the culms usually erect; panicle narrow, lax or dense |
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(29) |
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| 29 (28) |
Uppermost node in the median third of the culm |
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Poa sterilis |
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Uppermost node in the basal third of the culm |
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(30) |
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| 30 (29) |
Lowest lemma (2-)2.3-3(-3.2)mm long; spikelets usually 3-4mm long |
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Poa attenuata |
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Lowest lemma (2.8-)3-4.5mm long; spikelets 3-6.5mm long |
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(31) |
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| 31 (30) |
Green or glaucous plant, usually 25-50cm high; uppermost node about a third the way up the culm |
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Poa versicolor subsp. araratica |
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Very glaucous plant 10-25cm high (rarely higher); uppermost node in the lowest sixth of the culm |
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Poa glauca subsp. litwinowiana |
