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Achillea
See list of 5 species in this genus-
1a. Rays yellow; stems glandular-punctate
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2a. Stems villous; ultimate segments of leaf blades 1.5–8 mm wide; involucral bracts sparsely to moderately pubescent (i.e., the surface not concealed by hairs)
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2b. Stems villous-tomentose; ultimate segments of leaf blades usually narrower than 1 mm; involucral bracts moderately to densely pubescent abaxially (i.e., the surface largely concealed by hairs)
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1b. Rays white to pink; stems not glandular-punctate
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3a. Leaf blades subentire to serrate with short teeth; rays numbering (5–) 8–10 (–15) per capitulum, 3–5 mm long
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3b. Leaf blades pinnately dissected into narrow segments; rays numbering (4–) 5 (–6) per capitulum, 1–3 (–4) mm long
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4a. Leaves near the middle of the stem usually with 15 or more primary divisions, the blades lanceolate to linear, the divisions usually not plane
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4b. Leaves near the middle of the stem with 10 or fewer lobes, the blades elliptic to ovate, with plane lobes
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Each photo represents one species in this genus.