Flower:

Branching cluster of stalked flowers on the upper stem, the branches mostly erect to ascending. Flowers are 1 to 1½ inches across with 20 to 40 slender petals (ray flowers) and a yellow center disk that turns reddish purple with age. Ray color is violet to pale blue to nearly white.

The bracts (phyllaries) surrounding the base of the flower head are in 4 or 5 layers, very narrow, hairless to sparsely hairy along the edges, pale green with a lance-linear green tip that is usually spreading. Flower stalks are up to ~1 inch long, hairless to variously hairy, with a few narrow, leaf-like bracts below the flower.

Leaves and stems:

Leaves are alternate, 2 to 6 inches (to 15 cm) long, 3/8 to ~1 inch (1 to 3 cm) wide, tapering to a sharp point at the tip, and have a prominent center vein. Surfaces are hairless, the upper surface often light green and glossy; edges are toothless or with a few fine, widely spaced teeth.

Leaf bases are stalkless and typically have a pair of small lobes that clasp the stem. Basal leaves are lance to spatula-shaped with winged, sheathing stalks and wither away by flowering time along with lower stem leaves. Stems are single, mostly erect, and are hairless or hairy in lines. Loose to dense colonies may form from long rhizomes.

Fruit:

Fruit is a dry seed with a tuft of dull white to yellowish hair to carry it off in the wind.

Notes:

Shining Aster is a species of moist to wet places, found in scattered locations across Minnesota. It is recognized by the long, narrow, hairless, clasping leaves, stems that are hairless or hairy in lines, and panicle of erect to ascending branches with pale violet to nearly white flowers.

Shining Aster is sometimes lumped into Purple-stemmed Aster (Symphyotrichum puniceum) but is considered a separate species in Minnesota. While the two are very similar, particularly in leaf shape, S. puniceum leaves are rough, hairy along the midvein, tend to be less crowded on the stem, stems are more evenly hairy across the surface (not in lines), flowers tend to be a deeper color, and the panicle branches are mostly spreading to ascending, giving a more open appearance.