Page author: David Giblin
Epilobium densiflorum
dense-flower willowherb

Distribution: Occurring on both sides of the Cascades in Washington; Vancouver Island, British Columbia to Baja California, east to Montana, Utah, and Arizona.

Habitat: Moist to seasonally moist meadows, springs, shores, riparian zones, slopes, roadsides, and ditches.

Flowers: July-September

Origin: Native

Growth Duration: Annual

Conservation Status: Not of concern

Pollination: Flies


Annual, the stem simple or branched, 1.5-10 dm. tall, with gray, appressed hairs or soft, spreading hairs.


Leaves alternate, sessile, crowded, the lower ones lanceolate, 1.5-5 cm. long, mostly entire; floral leaves ovate to ovate-lanceolate, entire or remotely denticulate, up to 15 mm. long and 12 mm. broad.


Flowers sessile in elongate, crowded terminal and lateral spikes; calyx funnel-shaped, 1.5-2.5 mm. long, 4-lobed; petals 4, borne on the calyx, pale pink to rose, 3-8 mm. long, lobed up to half their length; ovary inferior, 4-celled; stamens 8, of two lengths.


Capsule slenderly spindle-shaped, 4-celled, 6-10 mm. long, straight and appressed to the stem, very short-beaked.

Accepted Name:
Epilobium densiflorum (Lindl.) Hoch & P.H. Raven
Publication: Phytologia 73(6): 457 [1993]. 1992.

Synonyms & Misapplications:
Boisduvalia densiflora (Lindl.) S. Watson [HC]
Boisduvalia densiflora (Lindl.) S. Watson ssp. pallescens Suskd.
Boisduvalia densiflora (Lindl.) S. Watson var. densiflora [HC]
Boisduvalia densiflora (Lindl.) S. Watson var. salicina (Rydb.) Munz
Boisduvalia densiflora (Lindl.) S. Watson var. salina (Rydb.) Munz, orthographic variant [HC]
Oenothera densiflorum Lindl.
Additional Resources:

PNW Herbaria: Specimen records of Epilobium densiflorum in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Epilobium densiflorum checklist entry.

OregonFlora: Epilobium densiflorum information.

E-Flora BC: Epilobium densiflorum atlas page.

CalPhotos: Epilobium densiflorum photos.

USDA Plants: Epilobium densiflorum information.

35 photographs:
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