Achnatherum diegoense |
Eriocoma nelsonii(synonym of Achnatherum nelsonii) |
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Nelson's needlegrass |
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Habit | Plants 40–175 cm tall; cespitose. | |
Culms | 0.7–2.4 mm thick, glabrous, sometimes slightly pubescent below the lower nodes. |
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Leaves | basal sheaths glabrous to sparsely or densely pubescent; margins sometimes ciliate; collars glabrous or somewhat pubescent, lacking tufts of hairs, ligules of basal leaves 0.2–0.7 mm, those of upper leaves 1–1.5 mm; blades flat in life but folded or rolled when dry, those of vegetative shoots 1.2–2.5 mm wide; culm leaves to 5 mm wide; outer surface glabrous but with scabrous margins; inner surface scabrous to pubescent, rarely glabrous. |
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Inflorescences | 9–36 × 0.8–2 cm; branches appressed; straight. |
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Glumes | 6–12.5 × 0.7–1.1 mm. |
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Florets | 4.5–7 × 0.6– 0.9 mm, usually round in cross section when mature. |
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Calluses | 0.2–1 mm; blunt to sharp; the dorsal side with a straight to acute boundary between the glabrous tip and the hairy portion. |
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Lemmas | evenly pubescent; hairs at mid-length 0.5–1 mm; tips with hairs to 2 mm and erect or ascending, with flexible, membranous lobes 0.1–0.4 mm; lemma awns 19–45 mm, persistent; bent twice; the first 2 segments scabrous or hairs shorter than 0.5 mm; terminal segment glabrous; straight. |
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Paleas | 33–67% as long as the lemmas, pubescent; hairs usually not exceeding the tips. |
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Anthers | 2–3.5 mm, lacking hairs at the tip. |
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2n | =36, 44. |
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Achnatherum diegoense |
Eriocoma nelsonii |
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Distribution | ||
Discussion | [Originally published in Flora of Oregon as Achnatherum nelsonii.] 2 subspecies. Achnatherum nelsonii is often confused with its close relatives. Achnatherum lemmonii differs from A. nelsonii in having narrower leaves and relatively longer paleas. In addition, A. lemmonii has thick, stiff lemma lobes. Achnatherum nevadense and A. occidentale differ from A. nelsonii in having spreading hairs on the lower two awn segments, but some A. occidentale individuals have short awn hairs and can be hard to distinguish from A. nelsonii var. nelsonii. Individuals intermediate between A. nelsonii and A. occidentale are occasionally encountered. |
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Source | Flora of Oregon, volume 1 | |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Achnatherum nelsonii, Stipa columbiana, Stipa nelsonii | |
Web links |
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