Canadanthus modestus (Modest Aster)

Plant Info
Also known as: Great Northern Aster, Giant Mountain Aster, Northwestern Sticky Aster
Family:Asteraceae (Aster)
Life cycle:perennial
Habitat:part shade, sun; cold, moist to wet; alder thickets, swamps, moist woods, boreal forest, along shores
Bloom season:August - October
Plant height:1 to 3 feet
Wetland Indicator Status:GP: FAC MW: FAC NCNE: FAC
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 7+petals Cluster type: panicle

[photo of flowers] Branching clusters of a few to many stalked flowers at the top of the stem and arising from upper leaf axils, with flowers sometimes single at branch tips. Flowers are 1 to 2 inches across with 20 to 40 petals (ray flowers) and a creamy white to pale yellow center disk that turns purplish with age. Ray color is light to dark purple, sometimes rosy purple.

[photo of bracts (phyllaries)] The bracts (phyllaries) surrounding the base of the flower are in 3 to 5 layers, mostly all about the same length, lance to narrowly triangular, pointed at the tip, green to purplish or purplish just at the tip, and densely covered in glandular hairs. Flower stalks are green to purple tinged and densely covered in glandular hairs with a few leaf-like bracts below the flowers that are glandular-hairy along the midvein.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of leaves] Leaves are mostly lance-elliptic, 2 to 5 inches long, 1/3 to 1¼ inches wide, tapering to a pointed tip, stalkless with a pair of small lobes (auricles) at the base that somewhat clasp the stem. Edges are toothless or with a few small, widely-spaced teeth. The lowest stem leaves are smaller and more scale-like and wither away by flowering time.

[photo of mid stem and leaf hairs] The upper leaf surface is sparsely covered in long hairs, the lower more densely so but may become hairless, except for long hairs along the midvein. Stems are ascending to erect, usually single, often purplish. The lower stem is hairless or nearly so, becoming densely covered in spreading hairs mid-stem, with appressed hairs on the flowering branches and glandular hairs on flower stalks.

Fruit: Fruit type: seed with plume

Fruit is a dry, hairy seed with a tuft of cinnamon colored hair to carry it off in the wind.


Modest Aster is a boreal species and Minnesota is at the southern tip of its range, it is subsequently restricted to the cold, north woods and wetlands of the Arrowhead region. It is easily distinguished from the Symphyotrichum group of asters by the dense covering of glandular hairs on phyllaries, bracts and flower stalks. The flowers otherwise resemble New England Aster (S. novae-angliae), which have more rays (40 to 100+) and a golden yellow disk.

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More photos

Photos courtesy Peter M. Dziuk taken in Lake County.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Jim Cramton - bemidji
on: 2023-09-01 00:52:53

Found on a roadside north of Karl's appliance on Minnkota Ave NW in full bloom.

Posted by: K Chayka
on: 2023-09-01 08:31:58

Jim, if you check the distribution map and habitat info, you'll see it is pretty unlikely you saw this on a Bimedji roadside. There are other blue or purple-flowered asters that are more likely.

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