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Muhlenbergia
See list of 12 species in this genusSee Peterson et al. (2010) for rationale for an expanded Muhlenbergia (i.e., one that includes Lycurus and other genera). Reference: Peterson (2003b).
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1a. Panicle dense and spike-like, the branches virtually absent; lower glume with 2 (–3) awns
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1b. Panicle open and diffuse to slender and contracted, but the branches discernable; lower glume with a single awn
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2a. Panicle open and diffuse, (2.5–) 3–30 (–41) cm wide; spikelets on long, thin pedicels (0.2–) 3–40 (–50) mm long
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3a. Lemmas without an awn; leaf blades 0.8–2 mm wide; pedicels (0.2–) 3–7 mm long; callus of the lemma glabrous
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3b. Lemmas usually with an awn 2–13 (–18) mm long; leaf blades 2–4 mm wide; pedicels 10–40 (–50) mm long; callus of lemma shortly pubescent
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2b. Panicle slender and contracted, 0.1–3 cm wide; spikelets subsessile or on short pedicels to 5 mm long
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4a. Callus of the lemma glabrous; leaves 0.5–2 mm wide, involute; plants cespitose or mat-forming
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4b. Callus of the lemma pubescent; leaves 1–7 mm wide, normally flat; plants with stems distributed along rhizomes or the stems sprawling, neither cespitose nor mat-forming
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5a. Glumes (3–) 4–8 mm long including the awns, 1.3–2 times as long as the lemmas
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6a. Internodes of the stem pubescent and dull, terete in cross-section, not keeled; anthers 0.8–1.5 mm long; ligules 0.2–0.6 mm long; mature caryopsis 1.0–1.6 mm long; margin of the lemma pubescent
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6b. Internodes of the stem glabrous, except sometimes immediately below the node, lustrous, elliptic in cross-section and keeled; anthers 0.4–0.8 mm long; ligules 0.6–1.5 (–1.7) mm long; mature caryopsis (1.2–) 1.4–2.3 mm long; margin of the lemma glabrous
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5b. Glumes 0.1–3.7 (–4) mm long including the awns, shorter than to equaling (up 1.2 times as long as) the lemmas
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7a. Glumes minute and veinless, the larger (i.e., upper) only 0.1–0.3 mm long; plants with sprawling stems that root at the lower nodes [Fig. 243], without rhizomes
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7b. Glumes 1–3.7 (–4) mm long, 1- or 3-veined; plants not rooting at the nodes, with rhizomes [Fig. 244]
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8a. Internodes of the stem glabrous and lustrous [Fig. 241]
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9a. Glumes 1–2.5 mm long, broad and overlapping at base, narrowing above to a slender, acuminate apex (i.e., the margins sigmoid curved); plants usually few-branched above the base, axillary panicles, if present, generally well exserted from the leaf sheaths; panicles 2–5 (–8) mm wide; ligules 0.3–1 mm long
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9b. Glumes 2–4 mm long, narrow and only slightly overlapping at base and gradually tapering throughout the length to a slender apex (i.e., the margins ± straight); plants usually much branched above the base with numerous axillary panicles that are partly included in the leaf sheaths; panicles (3–) 4–15 (–20) mm wide; ligules 0.7–1.7 mm long
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8b. Internodes of the stem pubescent and dull [Fig. 242]
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10a. Glumes definitely shorter than the lemmas, broad and overlapping at base, narrowing above to a slender, acuminate apex (i.e., the margins sigmoid curved) [Fig. 245]; anthers 1.1–2.2 mm long; caryopsis 2–2.3 mm long
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10b. Glumes nearly as long as or slightly longer than the lemmas, narrow and only slightly overlapping at base and gradually tapering throughout the length to a slender apex (i.e., the margins ± straight); anthers 0.3–0.8 mm long; caryopsis 1.1–2 mm long
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11a. Ligule 1–2.5 mm long; panicle loose, with pedicels 0.8–3.5 mm long; spikelets usually without anthocyanic pigments; anthers 0.4–0.8 mm long
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11b. Ligule 0.4–1 mm long; panicle dense, with pedicels up to 2 mm long; spikelets often tinged with anthocyanin; anthers 0.3–0.5 mm long
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Each photo represents one species in this genus.