Sisyrinchium birameum Piper; S. idahoense var. birameum (Piper) J. K. Henry; S. oreophilum E. P. Bicknell

Stems 2–2.5 mm wide, margins denticulate. Spathes: keels denticulate; outer less than 2 times inner, basally connate 3.8–7 mm; inner 20–30 mm. Outer tepals 13–17(–20) mm; filaments bluish violet. 2n = 64, 96.

Flowering late spring--summer. Moist meadows, stream banks; 0--2200 m; B.C.; Calif., Idaho, Mont., Oreg., Wash., Wyo.

The few dodecaploid populations of var. idahoense in eastern Oregon are morphologically indistinguishable from the far more common octoploid plants.