These are the tiny and slightly sloppy-looking aster flowers that peek out from hedges and pop up in cracks of sidewalks in September and October. The buds of the disk florets are bright yellow, but they turn deep brownish purple as they open. Both colors are usually present at the same time, giving the plant its calico pattern.

From Gray’s Manual: A. lateriflorus (L.) Britton. More or less pubescent, much branched ; leaves lanceolate or oblong-lanceolate, tapering or pointed at each end, sharply serrate in the middle; bracts of the involucre linear, acute or rather obtuse, imbricated in 3-4 rows. (A. diffusus Ait.) Thickets, fields, etc., very common from N. S. to Ont., and southw. Aug.-Oct. Extensively variable ; leaves larger than in either of the two preceding ; the involucre intermediate between them, as to the form of the bracts. Rays mostly short, white or pale bluish-purple.

Also known as Beggar-Ticks or Sticktight. It looks like a big single marigold from which someone has plucked off all the rays. As with Spanish Needles, the hooked seeds stick to animal fur or clothing. The species is variable, and Gray notes that it hybridizes even across genera. This plant grew at the edge of an alley in the South Side flats.

From Gray’s Manual: B. Frondosa, L. (COMMON BEGGAR-TICKS, STICK-TIGHT.) Smooth or rather hairy, tall (2-6° high), branching; leaves 3-5 divided; leaflets mostly stalked, lanceolate, pointed, coarsely toothed; outer involucre much longer than the head, ciliate below; achenes wedge-shaped, 2-awned, ciliate (the bristles ascending except near the summit). —Moist waste places; a coarse troublesome weed, the achenes, as in the other species, adhering to clothing, etc., by their retrorsely barbed awns. Hybrids occur with Coreopsis aristosa and other species. July-Oct.

UPDATED: An earler version of this post included a picture that was probably not Aster puniceus. Identifying asters is a fool’s game. Torrey & Gray’s Flora of North America lists 131 species of Aster, and the chances are good that the particular aster you’ve found by the roadside won’t exactly fit the description of any one of them. But this picture shows a plant that actually looks pretty much like what Aster puniceus is supposed to look like.

Now Symphyotrichum puniceum, but the generic name Symphyotrichum is still so little known that most people looking for this plant will still know it as Aster. These common blue asters like slopes above streams and squishy wet ground. They are quite variable: Britton & Brown say that “races differ in pubescence, leaf-form, and leaf-serration,” meaning that anything you say about the shape of the leaves or how rough or hairy they are has to be followed by the words “or not.” The leaves of these plants were rough and sandpapery, and the stem quite hairy. These grew on the bank of a brook near Wexford.

From Gray’s Manual of Botany: A puniceus, L.  Stem tall and stout 3-7° high, rough-hairy all over or in lines, usually purple below, panicled above; leaves oblong-lanceolate, not narrowed or but slightly so to the auricled base, rough above, nearly smooth beneath, pointed; heads 4-6″ high, subsessile; scales narrowly linear, acute, loose, equal, in about 2 rows; rays long and showy (lilac-blue, paler in shade). —Low thickets and swamps, very common.