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15. Poaceae Tribe TRITICEAE
小麦族 xiao mai zu
Authors: Shou-liang Chen & Guanghua Zhu
Herbs annual or perennial, with or without rhizomes. Culms tufted or solitary. Leaf anatomy non-Kranz, without microhairs; leaf sheath usually split to base, rarely closed; ligule leathery or membranous; leaf blade usually linear to lanceolate, flat or involute. Inflorescence a solitary, bilateral spike, linear to ovate; rachis flattened, tough, or fragile and disarticulating at base of internodes, side not facing spikelets ± convex (here referred to as "back"). Spikelets 1 per node or in groups of 2 or 3 (rarely more) per node, usually sessile, rarely with a short pedicel, with 1 to many florets and apical floret smaller or sterile, laterally or dorsiventrally compressed, usually disarticulating below each floret if rachis tough. Glumes membranous to leathery, usually persistent, sometimes awnlike or reduced. Lemma 5–11-veined, apically awned or awnless. Palea with 2 keels. Lodicules 2, free, entire or 2-lobed. Stamens 3. Ovary tipped by a small, fleshy, hairy appendage. Stigmas 2. Caryopsis ellipsoid or oblong, hollowed on hilum face, free or somewhat adherent to lemma and palea. Endosperm with starch grains simple, rounded. Chromosomes large, x = 7.
About 20 genera and 330 species: temperate and warm-temperate regions, mainly in the N hemisphere; 13 genera (one introduced) and 175 species (99 endemic, eight introduced) in China.
In this account, "first lemma" refers to the lemma of the basal floret in a spikelet. Chinese genera of economic value include Hordeum and Triticum (staple foods) and Agropyron, Elymus, Elytrigia, and Leymus (fine forage).
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| 1 |
Spikelets in groups of 2 or more per node of rachis |
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(2) |
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Spikelets 1 per node of rachis |
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(6) |
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| 2 (1) |
Spikelets dorsiventrally compressed; spike with rachis disarticulating, or if not then plants cultivated |
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(3) |
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Spikelets laterally compressed; spike with rachis not disarticulating |
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(4) |
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| 3 (2) |
Spikelets all sessile and similar in groups of 2 or 3 in regular, longitudinal rows; spike with rachis disarticulating |
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99 Psathyrostachys |
| + |
Spikelets in groups of 3 in regular rows: 2 lateral spikelets usually shortly pedicellate, 1 central spikelet sessile, or if 3 spikelets all sessile then spike with rachis not disarticulating. |
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100 Hordeum |
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| 4 (2) |
Glumes 1-veined, or at least distal glume 3- or more veined, usually broad, with lateral veins ± riblike. |
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102 Elymus |
| + |
Glumes 1–3(–5)-veined, narrow with indistinct lateral vein, setiform, or reduced |
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(5) |
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| 5 (4) |
Leaf blade stiff, harsh; glumes well developed, 1–3(–5)-veined, frequently keeled. |
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98 Leymus |
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Leaf blade flexible, herbaceous; glumes usually weakly developed or sometimes absent, subulate or linear-setiform, usually not keeled. |
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101 Hystrix |
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| 6 (1) |
Glumes 5–13-veined, veins parallel or divergent |
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(7) |
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Glumes 1–9(–11)-veined, veins converging toward apex |
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(8) |
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| 7 (6) |
Glumes 1- or 2-keeled, with 5–11 veins, lateral ones diverging into teeth, apex obtuse or bidentate. |
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109 Triticum |
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Glumes rounded abaxially, with 7–13 parallel or divergent veins, apex truncate, dentate or with 1–5 awns. |
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110 Aegilops |
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| 8 (6) |
Rachis fragile or falling entire; plants usually annual; lemma keeled or sharply so, keel pectinate spinulose or not |
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(9) |
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Rachis tough; plants perennial; lemma rounded abaxially or keeled only at apex with keel not pectinate spinulose |
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(10) |
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| 9 (8) |
Spike oblong to orbicular; spikelets with 3–10 florets; lemma keeled, keel not pectinate spinulose. |
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107 Eremopyrum |
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Spike linear to oblong; spikelets with 2 florets; lemma sharply keeled, keel pectinate spinulose. |
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108 Secale |
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| 10 (8) |
Spike broadly linear to narrowly oblong, with crowded spikelets, pectinately arranged on a tough rachis; glumes 1–5-veined, usually 1-keeled to base, or if not keeled then midvein prominent |
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(11) |
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Spike linear, usually with lax spikelets divergently arranged on a tough rachis; glumes 3–9(–11)-veined, veins parallel or convergent and often keeled only in distal half |
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(12) |
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| 11 (10) |
Apical spikelet usually sterile; glumes 1-keeled to base. |
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106 Agropyron |
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Apical spikelet usually well developed; glumes not keeled or keeled only at apex, rarely keeled throughout length. |
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105 Kengyilia |
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| 12 (10) |
Plants usually with long rhizomes; spikelets usually disarticulating below glumes; lemma usually without distinct callus at base. |
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104 Elytrigia |
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Plants tufted or with short rhizomes; spikelets usually disarticulating above glumes; lemma with distinct or obscure callus at base |
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(13) |
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| 13 (12) |
Lemma usually with distinct callus at base. |
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102 Elymus |
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Lemma usually with obscure callus at base. |
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103 Pseudoroegneria |
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List of lower taxa
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