Now classified under the genus Eutrochium by many botanists; we keep the older classification here for the convenience of Internet searchers.

There are two common species of Joe-Pye-Weed in our area; the easiest way to identify them is by the leaves, which in this species usually grow in whorls of four, and in E. fistulosum in whorls of six. (Of course, this distinction is not always reliable, but it works most of the time.) Both are spectacular and dignified flowers, which are finally finding their rightful place in perennial gardens as well as our roadsides and meadows. The dusty old-rose color of the flowers is unique, and the straight stems with their perfectly arranged whorls of leaves are some of nature’s most elegant constructions. This plant was one of a patch growing in a wet depression in Schenley Park, along with a larger population of E. fistulosum.

Britton describes the genus and the species:

EUPATORIUM L. Erect, perennial herbs, with opposite or verticillate, or sometimes alternate, often punctate leaves, and in our species cymose-paniculate discoid heads of white, blue or purple flowers. Involucre oblong, ovoid, campanulate, or hemispheric, the bracts imbricated in 2-severaI series. Receptacle naked. Corolla regular, its tube slender, its limb 5-lobed or 5-toothed. Anthers obtuse and entire at the base, appendiculate at the apex. Style-branches elongated, flattened, or thickened above, stigmatic at the base. Achenes 5-angled, truncate. Pappus of numerous capillary usually scabrous bristles arranged in I row. [Named for Mithridates Eupator, i.e., of a noble father.] About 475 species, mostly of warm or tropical regions.

Eupatorium purpureum L. JOE PYE or TRUMPET WEED. (I. F. f. 3615.) Glabrous or sparingly pubescent, 1-3 cm. high. Stem green or purple, usually smooth; leaves thin, verticillate in 3’s-6’s, ovate, oval, or ovate-lanceolate, petioled, acuminate, serrate, sometimes incised, 1-3 dm. long, 3-7 cm. wide; heads numerous; involucre cylindric, its bracts pink, oblong, obtuse, imbricated in 4 or 5 series, the outer shorter; flowers pink or purple, occasionally white. In moist soil. N. B. to Man., Fla. and Tex. Aug.-Sept.

A more delicate sort of sunflower. This one was growing at the edge of a hillside clearing in Scott Township.

Flower Heads. The disk is smallish and golden yellow. The matching golden rays are long and narrow; there were eight of them on each of the flower heads on this plant, but (as the specific name implies) there are more often ten on this species.

Leaves. Thin, smooth; ovate, pointed; toothed; upper leaves nearly sessile; lower on winged petioles.

Stem. Smooth and tough, green with a few red spots.

Gray describes the genus and the species:

HELIÁNTHUS L. Sunflower. Heads many-flowered; rays several or many, neutral. Involucre Imbricated, herbaceous or foliaceous. Receptacle flat or convex; the persistent chaff embracing the 4-sided and laterally compressed smooth achenes, which are neither winged nor margined. Pappus very deciduous, of 2 thin chafly scales on the principal angles, and sometimes 2 or more small intermediate scales. — Coarse and stout herbs, with solitary or corymbcd heads, and yellow rays; flowering toward autumn. (Named from helios, the sun, and anthos, a flower.)

§2. Perennials; receptacle convex or at length low-conical; lower leaves usually opposite.

Involucre looser, the bracts more acuminate or elongated or foliaceous.

Leaves all or most of them opposite, 3-nerved.

Leaves longer-petiolate, thinnish or sofl, coarsely serrate, commonly broad; bracts loose, hirsute-ciliate.

H. decapétalus L. Stem branching, 0.5-1.5 m. high, smooth below; leaves smooth or roughish, ovate, pointed, abraptly contracted into margined petioles; bracts lanceolate-linear, elongated, loosely spreading, sometimes foliaceous, the outer longer than the disk; rays about 10 (H. scrvphulariifolius Britton?) — Copses and low banks of streams, centr. Me. and w. Que. to Minn., Mo., and southw.

A tall and cheerful native flower that may be abundant in some areas and absent in others. It likes the edge of the woods, and seems to be happiest on a hillside. These plants were part of a large colony growing on a hillside, just below the edge of the woods, in Mount Lebanon, where they were blooming in late July; they were among the earliest in their patch to bloom.

Until the flowers appear, the plants closely resemble Ironweed (Vernonia spp.), and indeed another common name for them is “Yellow Ironweed.” The stems, however, are a dead giveaway: they have prominent “wings,” meaning that they are flattened out into a thin membrane along the edge.

The flower heads are also distinctive. The disk florets are unusually large, arranged pincushion-fashion. The drooping rays are irregular and rather sloppy; there may be only two of them, or up to eight, and they be be significantly different in size and shape.

However, though no one of the individual flower heads may be a florist’s showpiece, their effect en masse is quite decorative, and this is a very desirable native wildflower for those who have the space to let it run riot.

Gray describes the genus and the species:

ACTINÓMERIS Nutt. Heads many-flowered; rays neutral, few or none. Involucral bracts few, herbaceous, nearly equal, soon defiexed beneath the globular disk. Receptacle small, chaffy. Achenes flat, obovate, winged or wingless, at maturity spreading in all directions; pappus of 2-3 smooth persistent awns. —Tall branching perennials, with serrate feather-veined leaves tapering to the base and mostly decurrent on the stem. Heads corymbed ; flowers chiefly yellow. (Name from aktis, a ray, and meris, a part; alluding to the irregularity of the rays.)

A. alternifòlia (L.) DC. Stem somewhat hairy, usually winged above. 1-2 m. high ; leaves alternate or the lower opposite, oblong or ovate-lanceolate, pointed at both ends; rays 2-8, irregular. (A. squarrosa Nutt.; Verbesina alternifolia Britton.) — Rich soil, N. J. to Ont., Ia., Kan., and southw. Aug., Sept.

Once in a while, a Calliopsis or Plains Coreopsis grows with solid red flowers. Naturally, this trait has been seized on by breeders to produce reliably red varieties, and this plant may well be a descendant of one of those domesticated breeds. It was growing in a hillside meadow in Scott Township, where it was blooming in late July.

Gray describes the genus and the species:

COREOPSIS L. TICKSEED. Heads many-flowered, radiate; rays mostly 8, neutral, rarely wanting. Involucre double; each series of about 8 bracts, the outer foliaceous and somewhat spreading; the inner broader and appressed, nearly membranaceous. Receptacle flat, with membranaceous chaff deciduous with the fruit. Achenes flat, obcompressed (i.e. flattened parallel with the bracts of the involucre), often winged, not narrowed at the top, 2-toothed or 2-awned, or sometimes naked at the summit; the awns not barbed downwardly. — Herbs, generally with opposite leaves and yellow or party-colored (rarely purple) rays. Too near the last section of Bidens, but generally well distinguished as a genus. (Name from koris, a bug, and opsis, appearance; from the form of the achene.)

§1. Style-tips truncate or nearly so; outer involucre small and short; rays rosecolor or yellow, with brown base; pappus an obscure border or none.

С. tinctoria Nutt. Annual, glabrous, often 1 m. high; leaves 1-2-pinnately divided, the lobes lanceolate to linear; achenes oblong, wingless; rays yellow, with more or less of crimson-brown. — Minn, to Tex., etc.; common in cultivation; often escaping to roadsides, etc., eastw.

Also called Gray-Headed Coneflower or Pinnate Coneflower. This is a rare plant in Pennsylvania, though not farther west, and certainly not rare in this hillside clearing in Scott Township, where these flowers were blooming in late July. The flower heads are distinctive: a thimble-shaped cone, starting greenish-gray and becoming brown as the disc florets bloom, with long drooping yellow rays  that flutter in the breeze. The leaves are finely divided.

Gray places this species in the genus Lepachys. This is a curious example of the rule of priority in botanical nomenclature. The famous (and famously difficult) botanist, archaeologist, ethnographer, historian, journalist, explorer, philologist, unlocker of the secrets of the Maya, and proto-evolutionist C. S. Rafinesque described the genus Ratibida in 1818; a year later, he described the same genus in a different publication as Lepachys. Thus he has the peculiar distinction of having beaten himself to the naming of his own genus.