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threadleaf fleabane

Philadelphia fleabane

Habit Plants perennial, 9–40 cm; taprooted, with branching caudices. Plants annual, biennial, or short-lived perennial, 10–80 cm; roots fibrous, caudices usually simple.
Stems

erect, moderately to densely strigose, eglandular.

erect, sparsely to moderately hirsute to lanate, minutely 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.

withering by flowering, oblanceolate to nearly spatulate, 20–170 × 5–35 mm;

margins nearly entire, coarsely serrate, lobulate, or shallowly dentate;

surfaces slightly to moderately strigose or hirsute, eglandular.

Cauline leaves

gradually reduced distally or not.

oblanceolate to lanceolate to elliptic or oblong, 5–130 × 3–25 mm, distally reduced, bases clasping;

surfaces eglandular.

Involucres

4–6 × 7–11 mm.

3–6 × 6–15 mm.

Ray florets

20–40, white to purple;

rays 3–9 × 0.7–1.5 mm.

150–250, white to pink;

rays 2–7 × 0.2–0.5 mm.

Disc florets

corollas 2–4 mm.

corollas 2–3 mm.

Phyllaries

in 2–4 series;

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

in 2–3 series;

surfaces sparsely to moderately hirsute, minutely glandular.

Fruits

1–3 mm, sparsely strigose;

inner pappi of numerous barbellate bristles.

1–1.5 mm, sparsely to moderately strigose;

inner pappi of numerous barbellate bristles.

Heads

1–5 in corymb-like arrays, radiate.

(1)3–many in corymb-like arrays, radiate.

2n

=18.

=18.

Erigeron filifolius

Erigeron philadelphicus

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.

Disturbed areas, streambanks, fields, meadows, forest openings. Flowering Apr–Sep. 0–1900 m. All ecoregions. CA, ID, NV, WA; nearly worldwide. Native.

Source Flora of Oregon, volume 2, page 256
James Riser, Stephen Meyers
Flora of Oregon, volume 2, page 260
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. oreganus, E. peregrinus, E. petrophilus, 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 philadelphicus var. philadelphicus
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