OregonFlora: Erigeron tweedyi vs. Erigeron

	Erigeron tweedyi	Erigeron
		daisy, fleabane
Habit		Herbs, rarely subshrubs or small shrubs annual, biennial, or perennial.
Stems		usually erect to ascending, occasionally decumbent, glabrous to densely hirsute, glandular or eglandular.
Leaves		basal and/or cauline; basal sometimes withering by flowering, alternate, broadly obovate to oblanceolate to narrowly spatulate to linear; margins entire, lobed, or toothed; surfaces glabrous to densely hirsute, glandular or eglandular; cauline well developed or ± reduced distally, sessile or petiolate.
Inflorescences		heads solitary on scapes or scape-like stems or few to many in corymb-, raceme-, or panicle-like arrays.
Involucres		turbinate or campanulate to hemispheric.
Receptacles		flat to conic, pitted; paleae 0.
Ray florets		0 or in 1(2) series, pistillate; rays usually strap-shaped, sometimes filiform, sometimes very short or lacking, white, pink, lavender, purple, blue, yellow, or cream-colored.
Disc florets		usually bisexual; corollas short, yellow.
Phyllaries		usually in 2–3 series, numerous, often with a darkened medial or apical area; surfaces glabrous to densely hirsute, glandular or eglandular.
Fruits		± oblong, flattened to ± cylindric, 2–7-veined, pappi of 2 series, outer of crowns; scales, or short bristles, inner of usually antrorsely barbellate, often accrescent; bristles, sometimes lacking.
Heads		radiate, disciform, or discoid.

	Erigeron tweedyi	Erigeron
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion		Temperate areas nearly worldwide. ~390 species; 40 species treated in Flora. Erigeron needs a modern generic revision. There is little consistency in the amount of variation warranting specific status. often, there is greater morphological variation within species (particularly among varieties) than between species. Many species are defined by morphological minutia and/or a single character (e.g., direction of stem hairs). Heads with both peripheral pistillate (ray) florets (in one or two series) and central disc florets (radiate heads) are most common. Heads lacking obvious ray florets may have inconspicuous or missing pistillate rays (disciform heads: E. aphanactis, E. chrysopsidis var. austiniae) or the pistillate flowers may actually be absent (discoid heads: E. bloomeri, E. inornatus, E. petrophilus). Pistillate flowers lacking conspicuous rays may be obscured by the involucres or adjacent disc floret pappi. Close inspection under magnification is needed before determining that the pistillate flowers are truly missing. Some individuals, especially if sterile, depauperate, or of poor quality, are not identifiable without direct comparison with reference material, if at all. The rays of pistillate flowers may change color upon drying; it is important to record flower color at time of collection. Due to shrinkage and curling of the pistillate flower rays on dried specimens, care must be taken when assessing whether rays are strap-shaped (usually greater than 0.5 mm wide) or filiform (less than 0.5 mm wide).
Source		Flora of Oregon, volume 1
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. 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
Subordinate 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. 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
Web links	Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: CA, OR, WA 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

Erigeron tweedyi

Erigeron

daisy, fleabane

Habit

Herbs, rarely subshrubs or small shrubs annual, biennial, or perennial.

Stems

usually erect to ascending, occasionally decumbent, glabrous to densely hirsute, glandular or eglandular.

Leaves

basal and/or cauline;

basal sometimes withering by flowering, alternate, broadly obovate to oblanceolate to narrowly spatulate to linear;

margins entire, lobed, or toothed;

surfaces glabrous to densely hirsute, glandular or eglandular;

cauline well developed or ± reduced distally, sessile or petiolate.

Inflorescences

heads solitary on scapes or scape-like stems or few to many in corymb-, raceme-, or panicle-like arrays.

Involucres

turbinate or campanulate to hemispheric.

Receptacles

flat to conic, pitted;

paleae 0.

Ray florets

0 or in 1(2) series, pistillate;

rays usually strap-shaped, sometimes filiform, sometimes very short or lacking, white, pink, lavender, purple, blue, yellow, or cream-colored.

Disc florets

usually bisexual;

corollas short, yellow.

Phyllaries

usually in 2–3 series, numerous, often with a darkened medial or apical area;

surfaces glabrous to densely hirsute, glandular or eglandular.

Fruits

± oblong, flattened to ± cylindric, 2–7-veined, pappi of 2 series, outer of crowns; scales, or short bristles, inner of usually antrorsely barbellate, often accrescent; bristles, sometimes lacking.

Heads

radiate, disciform, or discoid.

Erigeron tweedyi

Erigeron

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Temperate areas nearly worldwide. ~390 species; 40 species treated in Flora.

Erigeron needs a modern generic revision. There is little consistency in the amount of variation warranting specific status. often, there is greater morphological variation within species (particularly among varieties) than between species. Many species are defined by morphological minutia and/or a single character (e.g., direction of stem hairs). Heads with both peripheral pistillate (ray) florets (in one or two series) and central disc florets (radiate heads) are most common. Heads lacking obvious ray florets may have inconspicuous or missing pistillate rays (disciform heads: E. aphanactis, E. chrysopsidis var. austiniae) or the pistillate flowers may actually be absent (discoid heads: E. bloomeri, E. inornatus, E. petrophilus). Pistillate flowers lacking conspicuous rays may be obscured by the involucres or adjacent disc floret pappi. Close inspection under magnification is needed before determining that the pistillate flowers are truly missing. Some individuals, especially if sterile, depauperate, or of poor quality, are not identifiable without direct comparison with reference material, if at all. The rays of pistillate flowers may change color upon drying; it is important to record flower color at time of collection. Due to shrinkage and curling of the pistillate flower rays on dried specimens, care must be taken when assessing whether rays are strap-shaped (usually greater than 0.5 mm wide) or filiform (less than 0.5 mm wide).

Source

Flora of Oregon, volume 1

Sibling taxa