Broad-lipped Twayblade

(Listera convallarioides)

 

   

 

Color Photograph: Western wetland flora: Field office guide to plant species. U.S.D.A. Soil Conservation Service, West National Technical Center.

Line Drawing: Britton, N.L., and A. Brown. 1913. An Illustrated Flora of the Northern United States and Canada, Second Edition.

 

Broad-lipped Twayblade (Listera convallarioides [Sw.] Nutt. ex Ell.)

Identification: Flowers small, yellow-green. Lower petal elongate, wedge-shaped, with a deeply notched apex. Surrounding "petals" (actually sepals) tinged with purple. Flowers arranged in a loose spike at the top of the plant. Plant with two leaves, opposite, ovate, and located just below the flowering spike. Plant 4 to 10 inches in height.

Distribution: Across Canada from Newfoundland to Alaska. Southward into California and most of the Rocky Mountain States. In the east found southward to New England, and Michigan.

Habitat: Broad-lipped Twayblade is found in swamps and woodlands.

Flowering period: June to August.

Similar Species: The single pair of opposite, ovate leaves just below the flowering spike is distinctive. The related species, Heartleaf Twayblade, is similar, but the flowers are purplish, not yellow-green. The lower petal of Heartleaf Twayblade is deeply forked, not just indented.

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