UPDATE: An incorrect species name was given in the article title, although the correct name appeared in the article text.
Also called Bushy Goldenrod, Grass-Leaved Goldenrod, Fragrant Goldenrod, and probably any number of other names. This is one of the class of flat-topped goldenrods that most botanists now put in their own genus, Euthamia, rather than lumping them in with Solidago the way older botanists did. Identification is easy, because this is the only flat-topped goldenrod reported to grow in the Pittsburgh area. These plants were growing beside a shopping-center parking lot in Banksville, where they were blooming in the middle of August.
Flowers. Heads in irregular loose flattish cymes; individual heads small; with a sweet scent, like chrysanthemum.
Leaves. Linear, sessile, alternate; dark green above and below; with three veins, the central vein much the strongest; underside somewhat rough if rubbed toward stem.
Stem. Strong, resists bending; not quite smooth; about 3 feet high (a meter or so).
Gray puts this in the genus Solidago with the rest of the goldenrods. We turn to Britton, therefore, for a description of the genus and species:
EUTHÀMIA Nutt. Erect, paniculately branched herbs, perennial by long rootstocks, with linear or linear-lanceolate entire sessile 1-5-nerved punctate leaves, and numerous small heads of both tubular and radiate yellow flowers, clustered in the large cymose, convex or nearly flat-topped inflorescence. Bracts of the involucre obtuse, appressed, somewhat glutinous. Receptacle flattish, flmbrillate, or pilose. Ray-flowers pistillate, usually more numerous than the disk-flowers, the rays small. Disk-flowers perfect. Anthers obtuse at the base. Style-branches with lanceolate appendages. Achenes top-shaped or oblong, villous-pubescent. [Greek, referring to the clustered heads.]
Euthamia graminifòlia (L.) Nutt. BUSHY or FRAGRANT GOLDENROD. Stem glabrous, sometimes slightly rough above, 6-12 dm. high. Leaves numerous, linear-lanceolate, acuminate or acute at each end, 2-12 cm. long, 4-8 mm. wide, minutely rough-pubescent on the margins and nerves of the lower surface; resinous dots few; heads 4-6 mm. high, sessile in capitate clusters arranged in a flat-topped corymbose cyme; involucre ovoid-campanulate, its bracts oblong or oblong-lanceolate, slightly viscid; disk-flowers 8-12. In moist soil, fields and roadsides, N. B. to the N. W. Terr., Fla., Neb. and Kans. July-Sept.
In Wild Flowers Every Child Should Know, Frederic William Stack gives us this description:
BUSHY, OR FRAGRANT GOLDEN-ROD
Solidago graminifolia. Thistle Family.
This species differs so much from the true Goldenrods, Solidago, with which it is classed, that many botanists regard it as the leading type of a separate and new genus, Euthamia, a Greek word referring to its clustered heads. The crushed leaves and flowers are fragrant. This, together with its flat top has often caused it to be mistaken for Tansy. Its slender, leafy, green stalk branches widely at the top. It is occasionally rough to the touch, and grows from two to four feet high. The long and very narrow grass-like leaves taper toward either end, and their margins are entire, but very rough. They are very small, and thin-textured, grayish-green in colour, and show three or five ribs. The flowers are very small and are closely grouped in small, round clusters at the tips of the projecting, wiry branches, which are so graduated in length as to form a flat-topped, flowering head. The whole top is very free and open, and has a neat, trim appearance. The flowers are light coloured, and have from twelve to twenty very short ray flowers. This plant is found in moist soil in fields and along roadsides, from July to October. It ranges from New Brunswick to the Northwest Territory, south to Florida, Nebraska, and Missouri.