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FOC | Family List | FOC Vol. 22 | Poaceae

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.

1 Palea keels smooth, glabrous, back deeply sulcate; hairs at apex of each rachilla internode 4–6 mm.   1 H. pubescens
+ Palea keels scabrid to ciliate, back flat at maturity; hairs at apex of each rachilla internode 1–3 mm   (2)
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   (3)
+ 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   (4)
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.   2 H. dahuricum
+ 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.   3 H. hookeri
4 (2) Panicle open, sometimes nodding; branches ascending or spreading, up to 10 cm   (5)
+ Panicle laxly to densely contracted; branches erect or narrowly ascending, usually less than 4 cm   (10)
5 (4) Lemma apex subentire or minutely denticulate   (6)
+ Lemma apex 2-toothed   (7)
6 (5) Culms 20–45 cm; ligules to 0.5 mm; rachilla internodes hairy throughout length.   4 H. abietetorum
+ Culms up to 80 cm tall; ligules ca. 1 mm; rachilla internodes hairy only in upper part.   5 H. leianthum
7 (5) Panicle branches in whorls of up to 8, with branchlets almost to base; lower culm internodes and sheaths villous.   6 H. yunnanense
+ Panicle branches 2–4 per node (up to 6 in H. altius), bare in lower part; lower culm internodes glabrous (sheaths sometimes pilose)   (8)
8 (7) Nodes of culm pubescent.   7 H. altius
+ Nodes of culm glabrous   (9)
9 (8) Leaf blades 10–25 cm, 3–5 mm wide; spikelets 1–1.4 cm.   8 H. junghuhnii
+ Leaf blades 6–11 cm, ca. 2 mm wide; spikelets 0.8–1 cm.   9 H. delavayi
10 (4) Panicle 10–17 cm; lemmas densely scabrid; awn arising from upper 1/3 of lemma, recurved, scarcely twisted.   10 H. schmidii
+ Panicle 2–9(–14) cm; lemmas smooth, scaberulous or puberulous; awn arising near middle of lemma, geniculate with twisted column   (11)
11 (10) Spikelets reddish violet; anthers 1–1.6 mm.   11 H. potaninii
+ Spikelets brown or tinged violet; anthers 3–4.2 mm   (12)
12 (11) Panicle densely contracted; axis and branches densely pubescent; culm pubescent below panicle; spikelets golden brown.   12 H. tibeticum
+ Panicle laxly contracted; axis and branches scabrid or puberulent only in upper part; culm glabrous below panicle; spikelets pale yellowish brown tinged violet   (13)
13 (12) Plant densely tufted; sheaths of culm leaves usually pilose; leaf blades scabrid on adaxial surface; anthers ca. 3 mm.   13 H. tianschanicum
+ Plant loosely tufted; sheaths of culm leaves usually glabrous; leaf blades densely puberulous on adaxial surface; anthers ca. 4 mm.   14 H. mongolicum

  • List of lower taxa


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