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75. Helictotrichon Besser ex Schultes & J. H. Schultes, Mant. 3 (Addit. I ad Mant. Cl. III): 526 [“326”]. 1827.
异燕麦属 yi yan mai shu
Authors: Zhen-lan Wu & Sylvia M. Phillips
Avenastrum Opiz; Avenula (Dumortier) Dumortier; Trisetum sect. Avenula Dumortier.
Perennials, tussocky, often rhizomatous. Leaf blades linear to setaceous, flat, folded or rolled; ligule membranous. Inflorescence a panicle, open or often contracted, sometimes without secondary branching. Spikelets with 2 to several fertile florets and 1 or 2 reduced sterile florets above; rachilla pilose, disarticulating below each floret; glumes lanceolate, slightly unequal, usually shorter than spikelet and often shorter than lemmas, hyaline to membranous, lower glume 1–3-veined, upper glume 3–5-veined, keel scaberulous, apex acute; floret callus shortly bearded; lemmas lanceolate, firmly membranous to leathery, rounded or weakly keeled, 5–7(–9)-veined, glabrous, awned from middle of back or slightly above, apex minutely to deeply 2–4-toothed; awn geniculate with twisted column, sometimes weakly so or almost straight; palea slightly shorter than lemma and enclosed within lemma margins, keels scabrid-ciliolate to ciliate. Ovary densely hairy toward apex. Caryopsis with linear hilum; endosperm sometimes liquid.
About 100 species: Europe eastward to Japan, North America, also on tropical mountains; 14 species (seven endemic) in China.
Most species provide good forage.
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| 1 |
Palea keels smooth, glabrous, back deeply sulcate; hairs at apex of each rachilla internode 4–6 mm. |
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1 H. pubescens |
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Palea keels scabrid to ciliate, back flat at maturity; hairs at apex of each rachilla internode 1–3 mm |
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(2) |
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| 2 (1) |
Leaf blades flat or folded, keeled, margins and abaxial midrib prominently white-thickened, adaxial surface not ribbed; leaf sheath margins connate for part of length; floret callus bearded on sides only |
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(3) |
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Leaf blades flat or rolled, margins and midrib not thickened, adaxial surface closely ribbed with deep grooves between; leaf sheath margins free to base; floret callus evenly bearded |
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(4) |
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| 3 (2) |
Rhizomes present, plant forming loose turf; leaf sheaths closed for more than 1/2 of length; leaf blades 5–12 mm wide; spikelets 2–2.5 cm. |
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2 H. dahuricum |
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Rhizomes absent, plant forming dense turf; leaf sheaths closed for less than 1/4 of length; leaf blades 2–5 mm wide; spikelets 1–1.8 cm. |
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3 H. hookeri |
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| 4 (2) |
Panicle open, sometimes nodding; branches ascending or spreading, up to 10 cm |
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(5) |
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Panicle laxly to densely contracted; branches erect or narrowly ascending, usually less than 4 cm |
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(10) |
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| 5 (4) |
Lemma apex subentire or minutely denticulate |
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(6) |
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Lemma apex 2-toothed |
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(7) |
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| 6 (5) |
Culms 20–45 cm; ligules to 0.5 mm; rachilla internodes hairy throughout length. |
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4 H. abietetorum |
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Culms up to 80 cm tall; ligules ca. 1 mm; rachilla internodes hairy only in upper part. |
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5 H. leianthum |
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| 7 (5) |
Panicle branches in whorls of up to 8, with branchlets almost to base; lower culm internodes and sheaths villous. |
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6 H. yunnanense |
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Panicle branches 2–4 per node (up to 6 in H. altius), bare in lower part; lower culm internodes glabrous (sheaths sometimes pilose) |
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(8) |
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| 8 (7) |
Nodes of culm pubescent. |
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7 H. altius |
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Nodes of culm glabrous |
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(9) |
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| 9 (8) |
Leaf blades 10–25 cm, 3–5 mm wide; spikelets 1–1.4 cm. |
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8 H. junghuhnii |
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Leaf blades 6–11 cm, ca. 2 mm wide; spikelets 0.8–1 cm. |
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9 H. delavayi |
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| 10 (4) |
Panicle 10–17 cm; lemmas densely scabrid; awn arising from upper 1/3 of lemma, recurved, scarcely twisted. |
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10 H. schmidii |
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Panicle 2–9(–14) cm; lemmas smooth, scaberulous or puberulous; awn arising near middle of lemma, geniculate with twisted column |
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(11) |
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| 11 (10) |
Spikelets reddish violet; anthers 1–1.6 mm. |
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11 H. potaninii |
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Spikelets brown or tinged violet; anthers 3–4.2 mm |
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(12) |
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| 12 (11) |
Panicle densely contracted; axis and branches densely pubescent; culm pubescent below panicle; spikelets golden brown. |
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12 H. tibeticum |
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Panicle laxly contracted; axis and branches scabrid or puberulent only in upper part; culm glabrous below panicle; spikelets pale yellowish brown tinged violet |
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(13) |
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| 13 (12) |
Plant densely tufted; sheaths of culm leaves usually pilose; leaf blades scabrid on adaxial surface; anthers ca. 3 mm. |
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13 H. tianschanicum |
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Plant loosely tufted; sheaths of culm leaves usually glabrous; leaf blades densely puberulous on adaxial surface; anthers ca. 4 mm. |
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14 H. mongolicum |
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List of lower taxa
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