Perennial herbs with corm-like scaly rootstocks. Stems erect, simple. Leaves alternate, mostly basal, narrow or sometimes rather broad, continuous with the ocreae. Ocreae elongated, oblique at the top, persistent. Flower-clusters contiguous, dense. Raceme oblong or cylindric, solitary, sometimes with bulblets replacing the lower flower-clusters. Calyx white or pale. Sepals 5, slightly enlarged but otherwise unchanged at maturity. Stamens 5-8, exserted; filaments very slender. Styles 3, slender, exserted, nearly straight; stigmas capitate. Achenes 3-angled, loosely included in the calyx. [Latin, double-twisted, referring to the shape of the rootstock.]

About 8 species, natives of boreal regions. Besides the following, two or more others occur in western North America. Type species: Polygonum Bistorta L.

1. Bistorta Vivipara (L.) S.F.Gray. Alpine Bistort. Serpent-Grass

Fig. 1645

Polygonum viviparum L. Sp. PI. 360. 1753.

Bistorta vivipara S. F. Gray, Nat. Arr. Brit. PI. 2: 268. 1821.

Perennial, mostly glabrous and somewhat glaucous; stems solitary or clustered, erect, simple, slender, 2-10' tall. Basal leaves oblong or lanceolate, 1'-8' long, rather acute at the apex, cordate or subcordate at the base, long-petioled; stem leaves narrowly lanceolate or linear, l'-3' long, the lower petioled, the upper sessile, their margins often revo-lute: ocreae long, clasping below, open above; raceme solitary, terminal, narrow, rather dense, bearing a number of dark colored bulblets about its base; calyx 5-parted, pale rose-color or white; stamens 8, exserted; style 3-parted, it's branches exserted; achene oblong, 3-angled.

Greenland and Labrador to Alaska, south to the high summits of the mountains of New England, in the Rocky Mountains to Colorado and to Washington. Also in arctic and alpine Europe and Asia. June-Aug.

1 Bistorta Vivipara L S F Gray Alpine Bistort Serp 1645