Ontario Wildflowers website

Asters (Aster)

Summary of Key Identification Points of Asters

This page covers only the most common Asters in Ontario. The key identification features are listed for each Aster species. You may find this page helpful when used in conjunction with the Newcombe & Peterson field guides, as well as the Owen Sound Field Naturalists book, Asters, Fleabanes & Goldenrods of the Grey-Bruce.
PLEASE NOTE: common names for Asters vary considerably, and when cross-referencing, you should always use the scientific name.
Please also see: Learning the Asters.

You may print a PDF version of this page for your own use: CLICK HERE.

New England Aster (Symphyotrichum novae-angliae)

  • flowers: many rays
  • flowers: long, narrow rays
  • flowers: rays dark purple; occasionally white-rayed flowers are found
  • leaves: clasping
  • habitat: fields
  • common
  • similar to: Smooth Aster, Purple-stemmed Aster, Amethyst Aster

Purple-stemmed Aster (Symphyotrichum puniceum)

  • flowers: disc flowers yellow becoming purple
  • flowers: rays light purplish-blue
  • leaves: clasping
  • leaves: may be hairy on upper surface
  • stem: smooth to densely hairy
  • stem: usually reddish-purple
  • habitat: wet places
  • common
  • similar to: New England Aster, Purple-stemmed Aster

Smooth Aster (Symphyotrichum laeve)

  • flowers: rays light purplish-blue
  • leaves: smooth, waxy, almost rubbery
  • stems: smooth
  • common
  • similar to: Purple-stemmed Aster, New England Aster

Amethyst Aster (Symphyotrichum x amethystinum)

  • hybrid between New England Aster & Heath Aster
  • characteristics are midway between these two species
  • leaves: size and form like Heath Aster
  • leaves: clasping like New England Aster
  • habitat: fields
  • uncommon
  • similar to: New England Aster, Heath Aster

Heath Aster (Symphyotrichum ericoides)

  • flowers: many, small, crowded, overlapping
  • flowers: rays very short
  • flowers: discs stay yellow longer
  • leaves: often loses lower leaves
  • stems: upper stems crowded with incurved hairs
  • habitat: fields
  • grows in patches (spreads vegetatively)
  • common
  • similar to: Calico Aster

Calico Aster (Symphyotrichum lateriflorum)

  • flowers: discs turn maroon quicker than others
  • flowers: individual corollas more deeply lobed than in other small-flowered white asters.
  • branches lateral, widely spreading
  • branches relatively long
  • habitat: slightly shady places
  • common
  • similar to: Heath Aster

Azure Aster (Symphyotrichum oolentangiense)

  • flowers: sparse rays
  • flowers: rays wide
  • flowers: rays light purplish-blue
  • leaves: don't have the lobing of Heart-leaved Aster
  • leaves: teeth few and obscure
  • leaves: feel like fine sandpaper
  • looser and more open than Heart-leaved Aster
  • less common
  • similar to: Heart-leaved Aster, Arrow-leaved Aster, Fringed Blue Aster

Fringed Blue Aster (Symphyotrichum ciliolatum)

  • flowers: inflorescence an open panicle
  • flowers: inflorescence many-branched; many tiny linear bracts
  • leaves: basal/lower: heart-shaped with little or no notch
  • stems: upper are pubescent; lower are smooth
  • habitat: open woods & meadows
  • les common
  • similar to: Heart-leaved Aster, Arrow-leaved Aster, Azure Aster

Arrow-leaved Aster (Symphyotrichum urophyllum)

  • flowers: white rays
  • flowers: discs yellow, turn maroon
  • flowers: inflorescence narrow, upward ascending branches; "very up"
  • leaves: largest leaves at bottom of stem
  • leaves: "arrow"-shaped (more like a diamond shape)
  • leaves: few; petiole winged
  • leaves: teeth few & inconspicuous
  • habitat: fields
  • common
  • similar to: Heart-leaved Aster

Heart-leaved Aster (Symphyotrichum cordifolium)

  • flowers: rays light purplish-blue
  • flowers: inflorescence scattered, not flat-topped
  • leaves: largest leaves at bottom of stem
  • leaves: teeth usually coarse
  • leaves: distinctive leaf base, widely notched, lobes often overlapping
  • habitat: edges of woods
  • common
  • similar to: Large-leaved Aster, Arrow-leaved Aster

Large-leaved Aster (Eurybia macrophylla)

  • flowers: early in season; earlier than Heart-leaved
  • flowers: inflorescence: more or less flat-topped
  • leaves: many non-flowering clusters of plants: just leaves
  • habitat: in the woods
  • common
  • similar to: Heart-leaved Aster

Flat-topped White Aster (Doellingeria umbellata)

  • flowers: rays white
  • flowers: discs yellow becoming brown
  • flowers: inflorescence flat-topped
  • leaves: upper surface - hairs pointing in one direction - easy to run finger along in one direction only
  • leaves: densely packed along upper stem
  • leaves: prominent veins
  • stem: smooth to densely hairy
  • habitat: moist areas
  • common

Panicled Aster (Symphyotrichum lanceolatum)

  • flowers: white rays, yellow discs
  • leaves: narrow
  • leaves: lower ones turn brown or are gone by flowering time - dead ones are spiralled
  • leaves: largest leaves are well up the stem
  • habitat: fields
  • common

Rush Aster (Symphyotrichum boreale)

  • flowers: sparse
  • leaves: long and very narrow
  • leaves: edges inrolled (slightly rolled under)
  • habitat: bogs
  • less common
  • similar to: Panicled Aster, Upland White Aster

Upland White Aster (Solidago ptarmicoides)

  • flowers: flat-topped cluster
  • flowers: white rays
  • flowers: few heads per plant, 1-2 per branch
  • leaves: narrow
  • leaves: basal leaves present at flowering time
  • leaves: smaller at top of stem
  • habitat: dry areas
  • common in certain areas
  • similar to: Rush Aster

Frost Aster (Symphyotrichum pilosum)

  • flowers: more disc flowers than any other white-rayed Aster
  • flowers: discs yellow, stay yellow
  • leaves: shaped like Panicled Aster
  • leaves: fuzzy
  • stem: dense hairs stick straight out; very fuzzy (but there's also a smooth-stemmed variety)
  • open, spreading form
  • habitat: fields
  • common