This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Herbs resembling Limnorchis in habit, but with short rounded tubers. Leaves mainly near the base of the stem, early withering.- Spike strict. Flowers white, greenish, purplish or yellowish. Sepals i-nerved, the lateral ones adnate to the claw of the lip. Petals 1-nerved. Lip with a median ridge, truncate or hastate at the base. Anther-sacs opening laterally. [Dedicated to Professor C. V. Piper, of Washington.]
P. unalaschensis Rydb. Bull. Torr. Club 28: 270. 1901.
Stem strict, 1°-2° tall; lower leaves oblanceolate, 4'-6' long, obtuse or acutish; upper leaves lanceolate to linear-lanceolate, alternate; spike 4'-12' long; bracts lanceolate or ovate-lanceolate, shorter than the flowers; flowers greenish; lateral sepals oblong-lanceolate; petals lanceolate, nearly as long as the lateral sepals; lip oblong-lanceolate, somewhat has-tately dilated at the base.