Platanthera obtusata Lindley 1835

5. P. obtusata (Pursh) Lindley,

op. cit. 284 (1835).

Roots cord-like, fleshy but scarcely tuberous. Plant 6-20 cm. Foliage- leaf solitary, basal, 4-6 x 1 -5-2 cm, elliptical, tapered to a sheath­ ing base which is largely enclosed in a hyaline sheath representing a second basal leaf; a third leaf, small and bract-like, is present on upper part of stem. Spike short, rather dense; flowers 3-6, greenish-white. Perianth-segments2-3 mm. Labellum 3-3-5 mm, rhombic-lanceolate, horizontal or somewhat deflexed. Spur 2-5-3 mm, curved, half as long as ovary. 2n= 126.

1 By D. A. Webb.

Calcareous

mountain heaths.

Arctic Fennoscandia. No Su. (E. & E. C. Asia, North America.)

The European plant belongs to subsp.oligantha (Turcz.) Hultén, Lunds Univ. Ârsskr. nov. ser., 39(1): 481 (1943) (P.oligantha Turcz., Lysiella oligantha (Turcz.) Nevski), which is also found in E. Siberia. Subsp.obtusata, which is confined to America, has an obovate leaf, a laxer spike, a longer, narrower labellum and a longer spur. Plants from E. North America are very distinct from those from Europe and Asia, but intermediates are found in Alaska.