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..
[Epipactis (Hall.) Zinn, Cat. PI. Hort. Goett. 85. 1757.] Tall stout herbs with fibrous roots and simple leafy stems. Leaves ovate or lanceolate, plicate, clasping. Flowers leafy-bracted, in terminal racemes. Sepals and petals all separate. Spur none. Lip free, sessile, broad, concave below, constricted near the middle, the upper portion dilated and petal-like. Column short, erect. Anther operculate, borne on the margin of the clinandrium, erect, ovate or semiglobose, its sacs contiguous. Pollinia 2-parted, granulose, becoming attached to the glandular beak of the stigma. Capsule oblong, beakless. [Named for Serapis, an Egyptian deity.]
Serapias Helleborine L. Sp. PI. 949. 1753.
Serapias viridiflora Hoffm. Deutsch. Fl. 2: 182. 1804.
Epipactis latifolia var. viridiflora Irm. Linnaea 16: 451.
1842. Epipactis viridiflora Reichb. Fl. Exc. 134. 1830.
Stem 1°-2° high, glabrous below, pubescent above. Leaves ovate or lanceolate, obtuse or acute, 1 1/2'-3' long, 9'-1 1/2' wide; flowers greenish yellow to purple; pedicels 2"-3" long; sepals 4"-5" long, lanceolate; petals narrower; lip expanded into a slightly undulate apex, tapering to a point; bracts lanceolate, longer than the flowers.
Quebec and Ontario to Massachusetts and Pennsylvania. Local; probably introduced. Widely distributed in Europe. July-Aug.