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Wisconsin Plant of the Week

Aster umbellatus Miller

Asteraceae (Aster or Sunflower Family)

Common Name:

flat-top aster


Flat-top aster is distinctive among Wisconsin asters in its flat-top floral arrangement and that itís one of the first asters to bloom beginning in late July.  In northern Wisconsin itís common in many habitats --  birch/hemlock woods, tamarack swamps, sedge meadows and also in sandy uplands. Further south itís restricted to wet habitats like sedge meadows and low open woods over peaty soils.

Individual flower heads are 1 to 2 cm across with fewer than 15 white ray flowers that tend to bend back and downward. The clusters may be up to 30 cm across.

The plants soread by creeping rhizomes and grow to 2 m tall on erect, smooth stems. Leaves are alternate with smooth edges, lance-shape, up to 15 cm long, and tapered at both ends. Some plants may have leaves with fine hairs.

Flat-top aster attracts nymphalid butterflies, especially the Harris checkerspot (Chlosyne harrisii) as a larval food source and an adult nectary. The Harris lays a mass of eggs on the leaves that are initially yellow and then turn red.

  • Origin of the name: Aster, L., aster, a star; umbellatus, L. umbella, diminutive of umbra, a shadow, and by extension a sunshade or umbrella, whose spokes resemble the flower arrangement.
  • Range:  E. N. Amer., Nfld. to Alberta, s. to MN, KY and the mountains further south
  • WI Range:  Statewide
  • Common associates: Poison sumac, royal fern, joe-pye weed
  • Wetland Indicator Status: FACW
  • Coefficient of Conservatism: C = 9 (S&W), C = 5 (MI)
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