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128. Tripogon Roemer & Schultes, Syst. Veg. 2: 34. 1817.
草沙蚕属 cao sha can shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Perennials, often small. Culms densely tufted, slender, unbranched. Leaf blades mainly basal, filiform to setaceous, usually involute; ligule a narrow membrane fringed with hairs. Inflorescence a solitary unilateral terminal raceme. Spikelets subsessile, biseriate, broadside to rachis, linear to elliptic, laterally compressed, florets 2 to several, rachilla disarticulating above glumes and between florets; glumes narrow, shorter than lemmas or upper glume exceeding lowest lemma, unequal, membranous, 1-veined or upper glume sometimes 3-veined, keeled, acute to emarginate and mucronate, lower glume often with a lobe or tooth on one side; lemmas lanceolate to ovate, membranous, 3-veined, glabrous, lightly keeled or rounded, 2-dentate, midvein produced into an awn, teeth usually also mucronate or awned; palea keels scabrid or ciliolate, often winged. Floret callus bearded. Stamens 1–3. Caryopsis narrow, trigonous to subterete.
About 30 species: Old World tropics, one species in tropical America; 11 species (five endemic) in China.
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| 1 |
Central awn much shorter than lemma; anthers 3 |
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(2) |
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Central awn slightly shorter to distinctly longer than lemma; anthers 1–3 |
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(4) |
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| 2 (1) |
Lemma midvein extended into 0.2–0.5 mm mucro; lateral veins not extended. |
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1 T. purpurascens |
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Lemma midvein extended into 0.5–2 mm awn; lateral veins extended into 0.2–0.7 mm mucros |
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(3) |
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| 3 (2) |
Culms 5–8 cm; racemes 2–4 cm, purple-brown. |
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2 T. humilis |
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Culms 10–30 cm; racemes 6–15 cm, gray-green. |
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3 T. chinensis |
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| 4 (1) |
Anthers 3 (rarely 2) |
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(5) |
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Anther 1 |
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(8) |
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| 5 (4) |
Central awn 1.8–3.3 mm; lower glume without lateral lobe |
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(6) |
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Central awn 5–11 mm; lower glume lobed on one side |
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(7) |
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| 6 (5) |
Racemes erect or slightly curved; upper glume 3.5–4.3 mm, apex subacute, mucronate; awn 1.8–3.3 mm. |
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4 T. sichuanicus |
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Racemes drooping; upper glume 4–5 mm, apex 2-denticulate; awn 3–4 mm. |
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5 T. debilis |
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| 7 (5) |
Plant robust, up to 50 cm; lemmas with lateral awns arising from tips of teeth; anthers 1.4–1.7 mm. |
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6 T. trifidus |
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Plant slender, up to 35 cm; lemmas with apical teeth between awns; anthers 0.5–0.9 mm. |
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7 T. rupestris |
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| 8 (4) |
Central awn distinctly longer than its lemma, flexuose or reflexed; lateral awns 1–2 mm |
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(9) |
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Central awn slightly shorter to slightly longer than its lemma; lateral awns 0–1 mm |
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(10) |
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| 9 (8) |
Raceme with closely imbricate spikelets; central awn flexuose, at most gently reflexed. |
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8 T. filiformis |
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Raceme with spaced spikelets; central awns all strongly and stiffly reflexed. |
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9 T. longearistatus |
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| 10 (8) |
Spikelets their own length apart or slightly imbricate; lemmas 3.3–4.5 mm; central awn 2.5–4 mm. |
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10 T. yunnanensis |
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Spikelets closely imbricate; lemmas 2.2–2.6 mm; central awn 1.8–2.8 mm. |
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11 T. liouae |
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List of lower taxa
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