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threadleaf fleabane

Erigeron oreganus

Gorge daisy, gorge fleabane, Oregon fleabane

Habit Plants perennial, 9–40 cm; taprooted, with branching caudices. Plants perennial, 5–15 cm; taprooted, caudices unbranched.
Stems

erect, moderately to densely strigose, eglandular.

decumbent to erect; hirsute with unequal hairs, sparsely glandular.

Basal leaves

persistent, linear to filiform, 20–80 × 0.5–2 mm;

margins entire;

tips rounded to acute or acuminate;

surfaces moderately to densely strigose.

persistent, obovate, 15–90 × 5–20 mm;

margins coarsely serrate to shallowly lobulate;

surfaces sparsely to moderately hirsute to strigose.

Cauline leaves

gradually reduced distally or not.

obovate to elliptic; little or not reduced distally;

surfaces sparsely to moderately hirsute.

Involucres

4–6 × 7–11 mm.

4–7 × 9–15 mm.

Ray florets

20–40, white to purple;

rays 3–9 × 0.7–1.5 mm.

30–60, pink to purple;

rays 4–5 × 0.5–1 mm.

Disc florets

corollas 2–4 mm.

corollas 3–5 mm.

Phyllaries

in 2–4 series;

surfaces moderately to densely strigose or villous, sometimes nearly glabrous distally, densely minutely glandular.

in 2–3 series, pale green with dark green medial stripe;

surfaces remotely hirsute, strongly stipitate-glandular.

Fruits

1–3 mm, sparsely strigose;

inner pappi of numerous barbellate bristles.

2–3 mm, moderately strigose;

inner pappi of several unbarbed to weakly barbellate twisted bristles.

Heads

1–5 in corymb-like arrays, radiate.

1–4, radiate.

2n

=18.

Erigeron filifolius

Erigeron oreganus

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Rocky areas, sagebrush, juniper and pine forests. Flowering Apr–Aug. 50–2200 m. BR, BW, Col, ECas, Lava, Owy. CA, ID, NV, WA; north to British Columbia, northeast to MT, southeast to UT. Native.

If subspecific taxa were recognized, Oregon specimens would correspond to the typical variety.

Shady cliffs, rocky slopes, crevices. Flowering May–Aug. 100–400 m. Casc. WA. Native.

This uncommon species is found only in the Columbia River Gorge.

Source Flora of Oregon, volume 2, page 256
James Riser, Stephen Meyers
Flora of Oregon, volume 2, page 259
James Riser, Stephen Meyers
Sibling taxa
E. acris, E. aliceae, E. annuus, E. aphanactis, E. aureus, E. bloomeri, E. cascadensis, E. cervinus, E. chrysopsidis, E. compositus, E. corymbosus, E. coulteri, E. decumbens, E. disparipilus, E. divergens, E. eatonii, E. elegantulus, E. foliosus, E. glacialis, E. glaucus, E. howellii, E. inornatus, E. karvinskianus, E. klamathensis, E. latus, E. linearis, E. lonchophyllus, E. nivalis, E. oreganus, E. peregrinus, E. petrophilus, E. philadelphicus, E. poliospermus, E. pumilus, E. simplex, E. speciosus, E. stanselliae, E. strigosus, E. tener, E. vagus
E. acris, E. aliceae, E. annuus, E. aphanactis, E. aureus, E. bloomeri, E. cascadensis, E. cervinus, E. chrysopsidis, E. compositus, E. corymbosus, E. coulteri, E. decumbens, E. disparipilus, E. divergens, E. eatonii, E. elegantulus, E. filifolius, E. foliosus, E. glacialis, E. glaucus, E. howellii, E. inornatus, E. karvinskianus, E. klamathensis, E. latus, E. linearis, E. lonchophyllus, E. nivalis, E. peregrinus, E. petrophilus, E. philadelphicus, E. poliospermus, E. pumilus, E. simplex, E. speciosus, E. stanselliae, E. strigosus, E. tener, E. vagus
Synonyms Erigeron filifolius var. filifolius, Erigeron filifolius var. robustior
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