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POACEAE Tribe AVENEAE
Annual or perennial herbs. Leaf-blades linear, usually flat; ligule a membrane. Inflorescence an open or contracted, sometimes spike-like, panicle. Spikelets all alike (rarely in cluster of about 7, only 1 of which is fertile), laterally compressed or ± terete, bisexual, 1-10-flowered, the florets all alike or the uppermost reduced, rarely the spikelets 3-flowered with the 2 lower florets reduced, male or barren and of different appearance; rhachilla disarticulating above the glumes and nearly always between them, often produced as a slender bristle, rarely the spikelets falling entire; glumes persistent, mostly equal, usually as long as or longer than the floret, membranous to chartaceous, sometimes hyaline; lemma hyaline or membranous to cartilaginous, rarely strongly laterally compressed and indurated, 3-5-nerved, entire or 2(-4)-lobed at the tip; awnless or awned from the back; awn usually geniculate with twisted subterete column, sometimes slender and straight; palea hyaline or rarely coriaceous, usually as long as the lemma, often small or wanting; lodicules 2; stamens 1-3; stigmas 1-2. Grain with small embryo and linear hilum; starch grains compound. Chromosomes large, basic number 7, rarely 6.
Genera ± 65; mainly in temperate regions of both hemispheres, extending to mountainous regions of the tropics; 17 genera and 55 species in Pakistan.
A large heteromorphous tribe formerly broken down into three smaller ones. Strictly 1-flowered genera were placed in Agrostideae, and while some of them are obviously derivatives from Aveneae, some, such as Phleum and Alopecurus present a quite different facies suggesting that Agrostideae ought to have been further split. Phalarideae was commonly taken to consist of three genera having 2 sterile lemmas below the fertile lemma, but two of these (Anthoxanthum and Hierochoe) are so much like other members of Aveneae that they were usually accommodated there rather than in Phalarideae.
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| 1 |
Spikelets strictly 1-flowered |
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(2) |
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Spikelets with more than 1 floret although the two lower-most may be reduced to small chaffy scales at the base of the fertile lemma |
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(8) |
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| 2 (1) |
Panicle very dense, cylindrical, spike-like or ovoid |
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(3) |
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Panicle lax, if dense then lobed or interrupted |
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(5) |
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| 3 (2) |
Glumes linear, 1-nerved, with a long densely ciliate setaceous tip; lemma with 2 long apical bristles and a dorsal geniculate awn; inflorescence an ovoid, softly and densely hairy head |
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Lagurus |
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Glumes broader, 3-nerved, without a ciliate setaceous tip, at most shortly awned; lemma awned or awnless but entire and without 2 apical bristles; inflorescence not softly and densely hairy |
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(4) |
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| 4 (3) |
Spikelets falling entire; glumes often connate below; lemma usually awned, sometimes awnless, the margins often connate below; palea absent |
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Alopecurus |
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Spikelets breaking up above the persistent glumes; glumes not connate below; lemma awnless, the margins not connate; palea almost as long as the lemma |
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Phleum |
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| 5 (2) |
Glumes with long slender awns; spikelets falling entire attached to the pedicel or part of it |
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Polypogon |
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Glumes awnless or shortly awned (in the latter case persistent); spikelets breaking up above the glumes or falling entire |
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(6) |
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| 6 (5) |
Glumes shortly awned |
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Agropogon |
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Glumes acute or acuminate |
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(7) |
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| 7 (6) |
Spikelets 4-9 mm long; callus bearded with hairs usually not less than a third the length of the lemma and often 2- 3 times as long |
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Calamagrostis |
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Spikelets 1.5-3.5(-4.5) mm long; callus not bearded, or if so then spikelet not more than 2.5 mm long |
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Agrostis |
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| 8 (1) |
Spikelets 3-flowered, the two lowest florets male or sterile |
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(9) |
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Spikelets 2-several-flowered, the lowest florets bisexual, the succeeding similar or reduced |
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(11) |
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| 9 (8) |
Fertile lemma indurated, shining, longer than the others, the latter reduced to small chaffy scales |
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Phalaris |
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Fertile lemma shorter than the sterile |
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(10) |
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| 10 (9) |
Spikelets lanceolate; lower glume about half as long as the upper |
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Anthoxanthum |
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Spikelets oblong-urceolate; glumes ± equal |
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Hierochloë |
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| 11 (8) |
Annuals |
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(12) |
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Perennials |
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(14) |
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| 12 (11) |
Spikelets large, (9-)14-30 mm long, pendant in a large open panicle up to 40 cm long |
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Avena |
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Spikelets smaller, 3-55(-7.5) mm long, erect in ± compact or lobed panicles rarely over 6 cm long |
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(13) |
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| 13 (12) |
Lemma bifid with a straight or slightly curved awn from just below the tip |
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Rostraria |
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Lemma prominently 2-toothed, the teeth setose, awned from above the middle with a geniculate awn spirally twisted in the lower half |
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Trisetaria |
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| 14 (11) |
Lemma tip 4-toothed or 2-lobed with the lobes lacerate; awn inserted near the base of the lemma or at least below the middle |
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Deschampsia |
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Lemma bifid, the lobes acute to aristulate; awn inserted above the middle or absent |
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(15) |
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| 15 (14) |
Lemmas awnless or with an awn up to 1.2 mm long |
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Koeleria |
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Lemma with an awn (2 .5-)4-22 mm long |
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(16) |
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| 16 (15) |
Spikelets large, 9-28 mm long; awn geniculate, strongly spirally twisted in the lower half, 10-22 mm long |
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Helictotrichon |
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Spikelets smaller, 4-8.5 mm long; awn not geniculate but strongly recurved, only faintly twisted below, 2.5-8(-9.5) mm long |
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Trisetum |
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List of lower taxa
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