Plants c. 50–140 cm tall, densely caespitose; rhizome stout, horizontal. Stems in dense rows or tufts, rigid, stout, c. 2–4 mm in diam., terete, faintly striate to smooth; ridges inconspicuous, usually 40–70; pith continuous, dense. Cataphylls few; upper cataphylls usually 10–12 (–20) cm long, tight, with margins thickened distally and overlapping to the top, mostly asymmetrical and subtruncate to emarginate below the apical awn-like blade; abaxial side usually dull chocolate-brown to castaneous-brown distally, deep brown to deep castaneous-brown at base, dull and scabridulous, adaxially glossy stramineous. Lower bract much exceeding inflorescence. Inflorescence wide, with usually fastigiate branches, 3–8 cm long, many-flowered. Tepals subequal, 2–3 mm long, narrowly lanceolate, especially the outer ones conspicuously subulate, pale castaneous with green central band; margins broad, membranous. Stamens 3 (4–6); anthers 0.7–1.0 mm long; filaments c. 0.6 mm long; style 0.1–0.2 mm long; stigmas reddish, c. 1 mm long. Capsule triseptate, oblong-ovoid to ellipsoid, 2–2.5 mm long, conspicuously trigonous especially above, obtuse to subacute, shorter than perianth, pale to dark castaneous-brown. Seeds narrowly ovoid, 0.4–0.5 × c. 0.2–0.3 mm, apiculate, reticulate; appendages absent.
Western coastal N America from Baja California, California, Oregon, Washington, British Colombia to SE Alaska. Reports from two places in Idaho probably also refer to this subspecies. 70: ASK. 71: BRC. 73: IDA, ORE, WAS. 76: CAL.
71. BRITISH COLOMBIA: New Westminster, 27 Aug 1911, M.O.Malte (LD); Vancouver Is., Sidney, N of Cole Bay, A.S.Harrison 12.2 (PRA); Vancouver Is., Roche Cove, J.A.Calder & MacKay 31530 (WS). 73. OREGON: Douglas Co., Umpqua R. valley, W.C.Cusick 4335 (OSC, WS). WASHINGTON: Seattle, King Co., 6 Jun 1931, W.J.Eyerdam (LD); Olympia, 1896, T.C.D.Kincaid (LD).