Spiranthes diluvialis
diluvial ladies'-tresses

Distribution: Occurring east of the Cascades crest in Washington; Washington to Idaho, Montana, Wyoming, and Colorado.

Habitat: Moist to wet meadows, marshes, and riparian areas.

Flowers: July-September

Origin: Native

Conservation Status: Endangered in Washington (WANHP)


Herbaceous terrestrial perennials, 20-62 cm tall; stems with foliaceous sheaths; roots fasciculate, slender tuberoids, fleshy, diameter to 1 cm.


Leaves persisting through flowering period, typically clustered near base of stem ascending; blades ascending, linear-lanceolate, up to 28 cm long and 1.5 cm wide.


Inflorescence a tightly-spiraled spike with 3 flowers per spiral, or less commonly loosely spiraled with more than 4 flowers per cycle; rachis usually sparsely pubescent or rarely densely pubescent, some trichomes capitate with obviously-stalked glands; flowers whitish, ascending; sepals distinct or connate at base, 7.5-15 mm; lateral sepals spreading to slightly curved inward, commonly raised above rest of flower or appressed; petals linear, apex acuminate; labellum often yellow in center, ovate or lanceolate or oblong, median constriction variably evident, sometimes nearly pandurate, 7-12 mm long and 2.5-6.8 mm broad, margins crisped or entire or apically dentate; basal calli prominent; veins not many, wide-spreading or parallel branching; spur mentum or absent; column short and cylindric; anther heart-shaped with acute or obtuse apex; pollinia club-shaped with slender viscidium; viscidia linear to linear-lanceolate; ovary sessile, cylindric, usually 4-10 mm.

Fruits :


Accepted Name:
Spiranthes diluvialis Sheviak
Publication: Brittonia. 36: 11, figs. 1C, D, 2A–C, F. 1984.

Synonyms & Misapplications:
Spiranthes romanzoffiana Cham. var. diluvialis (Sheviak) S.L. Welsh
Additional Resources:

PNW Herbaria: Specimen records of Spiranthes diluvialis in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Spiranthes diluvialis checklist entry.

E-Flora BC: Spiranthes diluvialis atlas page.

CalPhotos: Spiranthes diluvialis photos.

USDA Plants: Spiranthes diluvialis information.

6 photographs:
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