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threadleaf fleabane

Erigeron disparipilus

Snake River daisy, white cushion fleabane

Habit Plants perennial, 9–40 cm; taprooted, with branching caudices. Plants perennial, 8–22 cm; taprooted, with branching caudices.
Stems

erect, moderately to densely strigose, eglandular.

erect, sparsely to moderately hirsute to strigose, eglandular.

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, narrowly spatulate to narrowly oblanceolate-elliptic, 30–80 × 3–5 mm;

margins entire, with 1 prominent vein;

surfaces moderately to densely strigose, eglandular.

Cauline leaves

gradually reduced distally or not.

few, linear, 10–40 × 1–3 mm, reduced distally.

Involucres

4–6 × 7–11 mm.

3.5–8 × 12–18 mm.

Ray florets

20–40, white to purple;

rays 3–9 × 0.7–1.5 mm.

25–50, white or cream, occasionally fading to pink;

rays 4–8 × 1–3 mm.

Disc florets

corollas 2–4 mm.

corollas 3–4 mm.

Phyllaries

in 2–4 series;

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

in 2–3 series, usually with dark green medial area with or without orange stripe;

surfaces moderately to densely hirsute or strigose, moderately to densely glandular.

Fruits

1–3 mm, sparsely strigose;

inner pappi of numerous barbellate bristles.

1.5–3 mm, sparsely to moderately strigose;

inner pappi of numerous barbellate bristles.

Heads

1–5 in corymb-like arrays, radiate.

usually 1, radiate.

2n

=18.

Erigeron filifolius

Erigeron disparipilus

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.

Open rocky areas, ridges. Flowering Jun–Jul. 1100–1800 m. BW. ID, WA. Native.

Some floras recognize plants with stem hairs in the same orientation (versus mixed) as E. davisii. The ranges and habitat of these taxa are, however, sympatric. Until further evidence shows otherwise, there is no compelling reason to recognize E. davisii as distinct from E. disparipilus.

Source Flora of Oregon, volume 2, page 256
James Riser, Stephen Meyers
Flora of Oregon, volume 2, page 255
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. 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. oreganus, 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 Erigeron davisii, Erigeron engelmannii, Erigeron engelmannii ssp. davisii, Erigeron engelmannii var. davisii
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