Stems solitary from the upturned end of a mostly short and simple horizontal rhizome, erect, to 10 dm; lower lvs with 1-27 lfls 1-4 cm, the middle and upper smaller; fls crowded in a typically elongate and somewhat thyrsiform infl; cor 10-16 mm, fully as wide, the lobes longer than the tube; stamens about equaling or a little shorter than the cor; style conspicuously surpassing the stamens. Arbor-vitae bogs in n. Minn.; widespread in the w. cordillera. July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.