1. Euthamia graminifolia (L.) Nutt. (common flat-topped goldenrod)

Solidago graminifolia (L.) Salisb.

S. graminifolia var. nuttallii (Greene) Fernald

E. graminifolia var. nuttallii (Greene) W. Stone

Pl. 234 g–i; Map 979

Stems 40–120 cm long, sparsely pubescent with minute, spreading hairs, at least toward the tip. Leaf blades 1–12 cm long, 1–10 mm wide, relatively thick, the margins moderately roughened with minute, stout, ascending, stiff hairs, the surfaces glabrous or sparsely pubescent with minute, spreading hairs, moderately resinous with impressed or pustular glandular dots, the smaller leaves with 1 midvein, the larger leaves with 3 or occasionally 5 main veins. Involucre 3–5 mm long, relatively resinous, the bracts variously rounded to sharply pointed at the tip. Ray florets 15–25(–35), the corollas 1–2 mm long, the short ligule ascending. Disc florets 4–10(–13), the corolla 1.5–2.0 mm long, the lobes 0.3–0.7 mm long. 2n=18. August–October.

Uncommon, mostly in counties bordering the Missouri River (northern U.S. south to Wyoming, Oklahoma, and Georgia; Canada; introduced in Europe, Asia). Loess hill prairies, savannas, and bottomland forests; also roadsides.

The present treatment differs markedly from that of Steyermark (1963). Steyermark treated E. graminifolia (as Solidago) with two varieties, basing his treatment on earlier taxonomic studies summarized in Fernald (1950). He excluded the glabrous var. graminifolia from the Missouri flora but accepted a larger-headed variant with somewhat hairy leaves and stems as S. graminifolia var. nuttallii and a smaller-headed variant with leaves only minutely roughened along the margins as S. graminifolia var. media (Greene) S.K. Harris. He reported populations of var. nuttallii as occurring uncommonly in a few counties along the Missouri River, with var. media widespread in the state. Since that time, Missouri botanists have had great difficulty in using this treatment to distinguish the latter variety from E. gymnospermoides, as it turns out with just cause. Croat (1970) studied a number of morphological characters throughout the range of the two taxa and observed widespread intergradation between S. graminifolia and S. gymnospermoides var. media. Subsequently, Sieren (1970, 1981) studied plants of the complex in the field and herbarium from Illinois and Wisconsin west into the Great Plains. His research confirmed that plants previously treated as S. graminifolia var. media were better included within E. gymnospermoides and also that there was too much intergradation between different morphotypes within that species to allow formal recognition of varieties within that species.

Within E. graminifolia, Sieren (1970, 1981) accepted three strongly intergrading varieties, with the hairy, robust var. nuttallii perhaps the most distinctive element in the species. Missouri specimens are less hairy than those from the main portion of the range, and some authors (Cronquist, 1991) have questioned whether the variety is consistently distinguishable. The glabrous taxa var. graminifolia and var. major (Michx.) Moldenke supposedly differ from one another primarily in the length-to-width ratio of the larger leaves, and both occur mainly to the north of Missouri. Because these variants overlap considerably and do not seem to have much ecological or geographic separation, there seems little point in recognizing them.