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Each heath aster flowerhead is 1/3-1/2" across with 8-20 ray florets (usually 12) and 6-12 disk florets. The ray florets are sterile; the disk florets are perfect and fertile. The phyllaries occur in 3-4 series on the back of the flowerhead; they are blunt-tipped, often recurved away from the flowerhead, with a distinct apical spine. Also note the spines at the tips of the numerous needle-like bracts on the flower stems. (Note: hairy aster (S. pilosum) also has such apical spines but has larger flowers, rolled, needle-like phyllaries with a smaller spine, and spreading hairs on the stems.)

Symphyotrichum

Symphyotrichum ericoides

heath aster [Blooms: Sep – Nov]

Panicled aster's central stem gives rise to an 8" long panicle (4" wide) of flowerheads; panicles may also arise form lateral stems and the axils of upper leaves. The panicle branches tend to be hairier and more often grooved than the stems; there are bracts (1.5" long, 8 mm wide) at the base of the panicle branches and the base of the flowerhead stalks. Individual flowerheads are 1/2-3/4" across with 1.5" long flower stalks (peduncles). Flowerheads have 20-40 white (less often blue or violet), pistillate (no stamens) ray florets, and an equal number of perfect (pistils and stamens) disc florets that are initially yellow, turning red orange with age. Phyllaries (bracts) cover the back of the flowerhead in 3-6 overlapping layers; the phyllaries are narrow, green with paler bases, appressed or slightly spreading, with the outer layer shorter than the inner. The fruit is a 1.5-2 mm long gray seed with a tuft of dull white or yellowish hairs. It's easy to confuse panicled aster with other asters that have small, white flowerheads. Look for: (1) leaves with wedge-shaped (not rounded or heart-shaped) bases, (2) mature leaves hairless on both sides, (3) stems with lines of white hairs, and (4) flowerheads with at least 20 ray florets. (Count the "petals.")

Symphyotrichum

Symphyotrichum lanceolatum

panicled aster [Blooms: Aug – Oct]

Panicles of flowerheads up to 10" long and 6" across arise from the upper stems (and some side stems) of calico asters. Individual flowerheads are about 1/3" (8 mm) across, typically consisting of 8-15 white ray florets and 8-16 cream or light-yellow disc florets turning brown or reddish purple with age. The flowerheads sit on a 1/3" long, hairy flower stalk (peduncle) with a few leaf-like bracts along the peduncle. The base of the flowerhead is covered by phyllaries (bracts) in 3-4 overlapping layers; the phyllaries are sparsely hairy, appressed or slightly spreading, with a darker green lance- or diamond-shaped tip. The fruits are fuzzy dry seeds with a tuft of white hairs. Calico asters are distinguished from other small, white asters by: (1) very small flowerhead (<1/2"), (2) relatively few (9-16) ray florets/petals, (3) creamy white or pale (not bright) yellow disk florets, (4) lance-elliptic leaves with hairs only on the midvein, (5) stems with lines of soft, white hairs. Other asters (e.g., panicled aster) will have one or more of these characters, but not the full suite.

Symphyotrichum

Symphyotrichum lateriflorum

calico aster [Blooms: Sep – ?]

The upper stems of hairy aster give rise to 2 foot long, 1.25 foot wide panicles with a central rachis that produces spreading or ascending primary branches and smaller secondary branches that bear the flowerheads. Each flowerhead is 1/2-3/4" across with 15-35 white ray florets and 20-40 yellow disk florets that turn reddish purple or brown with age. The bracts (phyllaries) that surround the base of the flowerhead are present in 4-5 layers; they are 3 mm long and light green with a long, darker green tip. The edges of the phyllaries are often rolled under and thus may appear needle-like. The phyllaries and the bracts attached to the panicle branches both have a tiny spine at their tip. (Note: heath aster (S. ericoides) also has such spines but has smaller flowerheads, broad, blunt phyllaries with a larger spine, and the hairs on the stems are either appressed to the stem or are ascending.) The fruits are 1-1.15 mm long, tan colored, dry seeds with 3-4 longitudinal ribs and a tuft of white hairs. After blooming is completed, rosettes of 3" long, 1" wide, spoon-shaped basal leaves develop and persist through the winter into the spring, but wither away before blooming begins again.

Symphyotrichum

Symphyotrichum pilosum

hairy aster [Blooms: Aug – Nov]

The upper stems and branches (some arising from upper leaf axils) of white arrowleaf aster terminate in 6-18" long panicles of flowerheads; the panicles are 2-3 times longer than wide. Each flowerhead is 1/2-3/4" across with 8-15 pistillate, white (rarely pale lavender) ray florets and 10-15 perfect (both stamens and styles present) disk florets. The disc florets are initially yellow but turn pink or light purple with age such that the flowerheads with yellow disk florets are often in the minority on the plant. The individual disk florets strike me as being larger than on many asters. The phyllaries (bracts) covering the base of the flowerhead are narrowly lance-shaped, usually hairless, dark green in the middle tapering to narrow, stiff, green to purplish tips. The fruits are 2 mm long, purplish-brown dry seeds with longitudinal ribs and a tuft of hairs at one end. White arrowleaf aster is similar to Drummond's aster (Symphyotrichum drummondii) but is less hairy and has distinctly different phyllaries. Among asters with white flowerheads, only white arrowleaf aster has heart-shaped leaves. (Other asters with heart-shaped leaves typically have blue to violet flowers.)

Symphyotrichum

Symphyotrichum urophyllum

white arrowleaf aster [Blooms: Aug/Sep – ?]