One-flower kelseya or spiraea, alpine laurel

Eriogynia uniflora S. Watson, Proc. Amer. Acad. Arts 25: 130. 1890

Shrubs 3–6 dm diam. Leaves light green to grayish green, becoming brownish, marcescent, hardened. Flowers: sepals persistent, inflating radially with fruit maturity. Follicles brown, coriaceous, opening first along adaxial suture, later on abaxial suture. 2n = 18.

Flowering Apr–Aug. Cracks of limestone rock outcrops; 1800–3500 m; Idaho, Mont., Wyo.

Kelseya uniflora can form dense carpets or mats that may cover areas of cliff faces. The solitary flower is unique in Spiraeeae. This species is of interest as an unusual rock-garden plant; it is difficult to cultivate.