Key to Eriophorum
1. Spikes 2 or more, subtended by one or more leaflike involucral bracts.
2. Leaves narrow, elongate, folded or triangular in cross-section; involucral bracts solitary, shorter than the inflorescence...........................................E. gracile
2. Leaves mostly flattened, except at the tips; involucral bracts 2 or more with the longest equalling or surpassing the inflorescence.
3. Spikes crowded, the scales with several conspicuous ribs; perianth bristles orange-brown or coppery...........................................E. virginicum
3. Spikes loosely aggregated, the scales with single ribs; perianth bristles creamy-white to tawny.
4. Midribs of scales extending to the tips, sheaths green...............E. viridcarinatum
4. Midribs of scales not extending to the tips; sheaths blackish..........E. angustifolium
1. Spikes solitary, not subtended by leaflike involucral bracts.
5. Plants rhizomatous or stoloniferous, usually with solitary stems...............E. scheuchzeri
5. Plants without stolons or rhizomes, densely tufted.
6. Scales with broad, pale margins, the basal ones reflexed................E. vaginatum
6. Scales without pale margins, the basal ones not reflexed.
7. Perianth bristles pure white with silky sheen; plants 6-25 cm tall..............E. callitrix
7. Perianth bristles cream-coloured or yellow-tinged; plants 30-60 cm tall..............E. brachyantherum
Source: Illustrated Flora of British Columbia
