Platanthera ephemerantha
white-lip rein-orchid

Distribution: Occurring west of the Cascades crest in Washington; Alaska to California.

Habitat: Moist coniferous forest at low elevations.

Flowers: May-June

Origin: Native

Conservation Status: Review Group 1 in Washington (WANHP)


Herbaceous terrestrial perennials, 10-60 cm tall, erect, glabrous; stems unbranched, not angled, not swollen toward base; roots tuberous, few.


Leaves few, prostrate to erect-spreading, ephemeral, basal; blades sessile, lanceolate to oblanceolate, 5-18 cm long and 1.1-3.5 cm broad; cauline bracts ovate to linear-lanceolate.


Inflorescence sparsely flowered raceme, somewhat secund, 10-30 cm; rachis nearly or as long as peduncle; bracts 3-10 mm; flowers white, emit faint fragrance, harsh to honeylike; sepals oblong-elliptic, 1.8-3.5 mm long and 1-1.9 mm broad; dorsal sepal extending outward or somewhat curved; lateral sepals deflexed, slightly twisted; petals typically projecting forward and converging with the others, white with faintly green midvein, unevenly lanceolate, 2-4 mm long and 1 mm broad; labellum curved downward, triangular-ovate, 2-3 mm long and 1-2.8 mm broad; spur curved, attenuate, 1.5-4 mm; viscidia widely elliptic to ovate, 0.3-0.6 mm long and 0.2-0.4 mm broad; rostellum slightly elongate.


Capsules 5-9 mm, erect, subsessile; seeds cinnamon brown.

Accepted Name:
Platanthera ephemerantha R.M. Bateman
Publication: Ann. Bot. (Oxford) n.s., 104(3): 439. 2009.

Synonyms & Misapplications:
Piperia candida Rand. Morgan & Ackerman [FNA26]
Additional Resources:

PNW Herbaria: Specimen records of Platanthera ephemerantha in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Platanthera ephemerantha checklist entry.

E-Flora BC: Platanthera ephemerantha atlas page.

CalPhotos: Platanthera ephemerantha photos.

USDA Plants: Platanthera ephemerantha information.

12 photographs:
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