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The leafy stems of Drummond's aster end in a panicle 1/2-2 feet long and half as wide bearing white flowerheads with yellow or maroon centers. Individual flowerheads are 1/2-3/4" across; they have 10-15 ray florets and 13-15 disk florets. The ray florets have bright blue, purple, or white tubular corollas and white rays (petals); the disk florets have cream to yellow tubular corollas, turning deep purple or reddish purple with age. Both disk florets and ray florets are perfect with bright yellow anthers on the stamens and white, bifurcated styles, but the ray florets are sterile. The base of the flowerhead is covered with 4-5 series of overlapping, light green phyllaries (bracts). Each phyllary is 4-6 mm long, light green, with a diamond-shaped patch of dark green near their tip. The fruit is a dry seed with a tuft of attached brown to white hairs. Note that the leaf petioles are winged and the leaves are broad and toothed. The upper surface of the leaf is rough (unlike Short's aster, the most common species in Jackson Park that you might confuse with Drummond's aster). The even pubescence (down-like hairs) on the underside of the leaves and along the stems distinguishes Drummonds aster from the other look-alike aster in Jackson Park, white arrowleaf aster (Symphyotrichum urophyllum). The phyllary pigmentation is also distinctive.

Symphyotrichum

Symphyotrichum drummondii

Drummond's aster [Blooms: Sep – ?]

Skyblue aster's central stem terminates in a 6-18" long panicle of flowerheads; the panicle is twice as long as wide. The panicle has a central stalk (rachis), several primary branches and numerous secondary (off the primary) and tertiary (off the secondary) branches that end in flowerheads. The branches have scale-like, 3/4" long leafy bracts spaced along their lengths. Individual flowerheads are 1/2-3/4" across with 10-25 lavender or pale blue ray florets and 20-25 disk florets. The disk florets are initially yellow, turning reddish-purple with age; they seem to me to be unusually large for an aster. The phyllaries (bracts) surrounding the base of the flowerhead are small (2 mm) and tightly appressed, each with a diamond-shaped green tip and often with a spot of blue-purple at the very tip. The fruits are bullet-shaped, 1.5-2mm long dry seeds, purplish brown, with a tuft of hairs. Skyblue aster is similar to smooth blue aster (S. laeve), but that species has sessile leaves; sky blue aster has petioles on the lower and middle leaves, only the upper leaves are sessile. Skyblue aster is also similar to Short's aster (Symphyotrichum shortii), but the latter has upper leaves with a heart-shaped base rather than smoothly tapering to a sessile attachment as in skyblue aster. Generally, skyblue aster is most easily identified by the long, narrow, arrowhead-shaped lower leaves that feel like fine sandpaper on both surfaces.

Symphyotrichum

Symphyotrichum oolentangiense

skyblue aster [Blooms: Sep – Oct]