OregonFlora: Erigeron elegantulus vs. Erigeron davisii

	Erigeron elegantulus	Erigeron disparipilus (synonym of Erigeron davisii)
	dwarf blue fleabane, volcanic fleabane	Snake River daisy, white cushion fleabane
Habit	Plants perennial, 4–10 cm; taprooted, with branching caudices.	Plants perennial, 8–22 cm; taprooted, with branching caudices.
Stems	erect to basally ascending, sparsely to moderately strigose, eglandular.	erect, sparsely to moderately hirsute to strigose, eglandular.
Basal leaves	persistent, linear to filiform, 20–50 × 0.5–1 mm, white, bases sheathing; margins entire; tips round to acute or acuminate; surfaces sparsely to moderately 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	abruptly reduced and usually restricted to basal ? of stem, bases sheathing.	few, linear, 10–40 × 1–3 mm, reduced distally.
Involucres	3–5 × 8–11 mm.	3.5–8 × 12–18 mm.
Ray florets	15–30, lavender to purple; rays 3–8 × 0.7–1.3 mm.	25–50, white or cream, occasionally fading to pink; rays 4–8 × 1–3 mm.
Disc florets	corollas 2.5–3.5 mm.	corollas 3–4 mm.
Phyllaries	in 3–4 unequal series; surfaces sparsely strigose, eglandular.	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	1–2 mm, nearly glabrous to sparsely strigose; inner pappi of numerous barbellate bristles.	1.5–3 mm, sparsely to moderately strigose; inner pappi of numerous barbellate bristles.
Heads	1, radiate.	usually 1, radiate.
2n	=27.

	Erigeron elegantulus	Erigeron disparipilus
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Rocky areas, sagebrush, coniferous forests. Flowering Jun–Aug. 700–2500 m. BR, BW, Casc, Owy. CA. Native.	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. 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	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. philadelphicus, E. poliospermus, E. pumilus, E. simplex, E. speciosus, E. stanselliae, E. strigosus, E. tener, E. vagus
Synonyms		Erigeron davisii, Erigeron engelmannii, Erigeron engelmannii ssp. davisii, Erigeron engelmannii var. davisii
Web links	Local floras: CA, OR Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Erigeron disparipilus

(synonym of Erigeron davisii)

dwarf blue fleabane, volcanic fleabane

Snake River daisy, white cushion fleabane

Habit

Plants perennial, 4–10 cm; taprooted, with branching caudices.

Plants perennial, 8–22 cm; taprooted, with branching caudices.

Stems

erect to basally ascending, sparsely to moderately strigose, eglandular.

erect, sparsely to moderately hirsute to strigose, eglandular.

Basal leaves

persistent, linear to filiform, 20–50 × 0.5–1 mm, white, bases sheathing;

margins entire;

tips round to acute or acuminate;

surfaces sparsely to moderately 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

abruptly reduced and usually restricted to basal ? of stem, bases sheathing.

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

Involucres

3–5 × 8–11 mm.

3.5–8 × 12–18 mm.

Ray florets

15–30, lavender to purple;

rays 3–8 × 0.7–1.3 mm.

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

rays 4–8 × 1–3 mm.

Disc florets

corollas 2.5–3.5 mm.

corollas 3–4 mm.

Phyllaries

in 3–4 unequal series;

surfaces sparsely strigose, eglandular.

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

1–2 mm, nearly glabrous to sparsely strigose;

inner pappi of numerous barbellate bristles.

1.5–3 mm, sparsely to moderately strigose;

inner pappi of numerous barbellate bristles.

Heads

1, radiate.

usually 1, radiate.

=27.

Erigeron disparipilus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Rocky areas, sagebrush, coniferous forests. Flowering Jun–Aug. 700–2500 m. BR, BW, Casc, Owy. CA. Native.

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