1	Perianth bristles usually 6, 3–9 mm in fruit, usually antrorsely barbed; spikelets 3–10 mm in fruit.		11 Eriophorum crinigerum
+	Perianth bristles usually 10–25, 10+ mm in fruit, smooth; spikelets 10+ mm in fruit.		(2)
2 (1)	Spikelets solitary, erect, without blade-bearing involucral bracts; distal leaves on culms bladeless or with blades not more than 1 cm; proximal scales of spikelets usually empty.		(3)
+	Spikelets usually 2 or more, spreading or nodding, subumbellate or capitate, subtended by 1 or more blade-bearing involucral bracts, sometimes reduced to sheaths; distal leaves on culms with blades at least 1 cm; proximal scales of spikelets usually subtending flowers.		(7)
3 (2)	Culms usually solitary; empty proximal scales usually not more than 7.		(4)
+	Culms densely tufted; empty proximal scales usually 10 or more.		(5)
4 (3)	Anthers not longer than 1.5 mm; perianth bristles bright white; spikelets broadly obovoid to subglobose in fruit; fertile scales with hyaline margins not more than 1 mm wide.		6 Eriophorum scheuchzeri
+	Anthers 1 mm or longer; perianth bristles red-brown to white; spikelets globose in fruit; fertile scales with hyaline margins at least 1 mm wide.		7 Eriophorum chamissonis
5 (3)	Proximal scales spreading or reflexed in fruit, with white-hyaline margins to 1 mm wide; perianth bristles pure white in fruit; distal sheaths on culms inflated.		8 Eriophorum vaginatum
+	Proximal scales appressed to ascending, without conspicuous whitish margins; perianth bristles white or brownish; distal sheaths on culms inflated or not.		(6)
6 (5)	Culms to 70 cm, smooth; sheaths evenly distributed along culms, distal not inflated, bladeless; proximal scales with broad ribless margins; perianth bristles creamy white to pale brown; anthers to 2 mm .		10 Eriophorum brachyantherum
+	Culms not more than 25(–50) cm, rough distally; sheaths mostly confined to proximal 1/2 of culm, often with short blade; proximal scales with ribs ± to margins; perianth bristles white to pale brown; anthers to 1 mm.		9 Eriophorum callitrix
7 (2)	Inflorescences with single blade-bearing bract; leaf blades channeled in cross section for entire length, not more than 1.5(–3) mm wide.		(8)
+	Inflorescences with (1–)2–5 blade-bearing bracts; leaf blades flat at least in proximal 1/2, 1.5–6+ mm wide.		(10)
8 (7)	Anthers 2–5 mm; longer scales 5–10 mm, proximal scales without lateral ribs.		3 Eriophorum angustifolium
+	Anthers 1–2(–2.5) mm; longer scales 3–4.5 mm, proximal (2–)3–9-ribbed, lateral ribs usually thinner and shorter than central.		(9)
9 (8)	Distal leaf blades 30–250 mm, longer than sheath; culms scabrous distally; scales with at least some red-brown.		4 Eriophorum tenellum
+	Distal leaf blades 10–40 mm, shorter than sheath; culms distally smooth; scales black or dark gray.		5 Eriophorum gracile
10 (7)	Scales brown often with green center, ribs obscure or several equally prominent; perianth bristles usually brown, at least proximally, rarely entirely white.		1 Eriophorum virginicum
+	Scales greenish gray to black with pale tip, midrib prominent; perianth bristles white or pale brown.		(11)
11 (10)	Scales with midrib prominent and enlarged towards tip, sometimes excurrent; anthers 0.8–2 mm; peduncles scabrous.		2 Eriophorum viridicarinatum
+	Scales with midrib fading toward tip; anthers (2–)2.5–5 mm; peduncles smooth or scabrous.		3 Eriophorum angustifolium