Flower:

Flowers are in an open branching cluster (panicle) at the top of the plant. Individual flowers are about 1 to 1½ inches across with 12 to 25 pale blue ray flowers (petals) and yellow center disc flowers that turn red with age.

The bracts (phyllaries) surrounding the base of the flower are narrow, flattened, and a bit irregular, sometimes tinged purple at the tips. The flower stalks are of varying lengths, with a few narrow leaf-like bracts along a stalk. A plant typically has fewer than 50 flowers.

Leaves and stem:

Leaves are thin, generally heart-shaped, to 5 inches long and 2 inches wide with a sharply pointed tip and “winged” leaf stalk. Edges are toothed with fine hairs all around the edge and smooth to sparsely hairy on the underside, more densely so along the midvein. Basal and lowest stem leaves have long stalks with narrower wings, becoming shorter stalked with wider wings as they ascend the stem. Leaves nearest the flowers may have no stalk. Basal and lower leaves usually wither away by flowering time. Stems may be green or reddish and are smooth to sparsely hairy, especially near the flowers. 1 to 3 stems arise from the base; stems are erect to ascending to nodding.

Fruit:

Fruit is a dry seed with a tuft of white hairs to carry them off in the wind.

Notes:

Lindley's Aster is one of the more common blue asters in Minnesota, found in most counties from the Metro north, and seen along roadsides and woodland edges in late summer. Asters can be difficult to ID. Lindley's Aster is distinguished by a combination of traits: smooth to sparsely hairy, thin, heart-shaped leaves with toothed edges and broadly winged stalks, 1-inch blue to lavender flowers with 12 to 25 rays, and a panicle with up to 50 flowers. Of the other blue/violet asters with heart-shaped leaves, Blue Wood Aster (Symphyotrichum cordifolium), Drummond's Aster (S. drummondii), and Short's Aster (S. shortii) all have hairier leaves and stems, especially on the underside, and the latter two species are found south of the Metro. Big-leaf Aster (Eurybia macrophylla) has significantly larger, more deeply heart-shaped leaves near the base, and more or less flat flower clusters. Arrowleaf Aster (S. urophyllum) also has heart-shaped leaves and winged stalks but has smaller white flowers.