Symphyotrichum ascendens. Synonym: Aster ascendens. (Western Aster)
Asteraceae (Sunflower Family)

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, September 13, 2021.

Symphyotrichum ascendens. Synonym: Aster ascendens. (Western Aster)
Asteraceae (Sunflower Family)

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, September 13, 2021.

In the top photograph the ray flower petals appear white but they are actually a light blue/violet, closer to the photograph immediately above. Sunlight often makes light blues and pinks appear white, so if I keep the photo image a bit dark, the light colors are truer to life.

Symphyotrichum ascendens. Synonym: Aster ascendens. (Western Aster)
Asteraceae (Sunflower Family)

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, August 28, 2015 and September 13, 2021.

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, August 28, 2015.

Symphyotrichum ascendens can grow to three or four feet tall, has multiple flower heads, and often occurs in large patches because it is rhizomatous.

Welsh indicates that this species "is the most common, most widespread, most commonly collected, and most variable aster species, having been named not fewer than sixteen times". It shares characteristics with and is difficult to distinguish from several other common Symphyotrichum because it is derived from the hybridization of S. spathulatum and S. falcatum and it backcrosses with these species.

Linnaeus named the Aster genus in 1753 and John Lindley named this Aster ascendens in 1834 from a specimen collected by Thomas Drummond on the banks of the Saskatchewan.  In 1995 Guy Nesom made the case for moving many members of the Aster genus to Symphyotrichum and that new classification is now accepted by most botanists. 

Trichomes are hairs and "symphy" means "coming together".  So "Symphyotrichum" refers to hairs growing together, probably referring to the line of hairs on several members of this genus. "Ascendens" is Latin for "rising upwards", perhaps referring to the upward pointing leaves or the tall and upright stature of this Symphyotrichum species.

Symphyotrichum ascendens. Synonym: Aster ascendens. (Western Aster)
Asteraceae (Sunflower Family)

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, August 28, 2015.

One characteristic that helps separate S. ascendens from some other Symphyotrichum is the shingled phyllaries. The white arrows point to the phyllaries which overlap each other like shingles on a roof.

Another distinguishing characteristic is the rounded tips of the outer phyllaries (see the phyllary pointed to by the bottom arrow).

Ray corollas are purple to violet or pink, rarely white. Ray corollas of the very similar S. falcatum are almost always white.

Symphyotrichum ascendens. Synonym: Aster ascendens. (Western Aster)
Asteraceae (Sunflower Family)

Foothills, montane. Woodlands, openings, roadsides. Summer, fall.
East Fork Trail, August 28, 2015.

Leaves vary widely from less than a centimeter long to over 15 centimeters long and hairiness varies also, from glabrous to pubescent, but leaves are usually ciliate, i.e., fringed with hairs. Lower leaves are often larger than upper ones, are often deciduous at anthesis (flowering time), and are commonly petiolate (whereas upper leaves are often sessile).

Stems hairs and leaf hairs are strigose, i.e., short, pointed, and appressed.

Also see Symphyotrichum foliaceum & Symphyotrichum spathulatum
and
Symphyotrichum ericoides, Symphyotrichum falcatum, & Symphyotrichum lanceolatum

Range maps © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Symphyotrichum ascendens