Coefficient of Conservatism:
Coefficient of Wetness:
R. W. Smith
Fields, prairie remnants, roadsides, fencerows, thickets; meadows, marshy ground, fens, moist shores, moist savannas; borders of rivers, forests, and swamps.
Involucre length has to be measured carefully on mature heads to be sure of the distinction from the small-headed S. canadensis. Measure several involucres to get a majority opinion if necessary; S. gigantea has involucres of similar size (or sometimes a trifle smaller), but the stem is glabrous beneath the inflorescence and the leaves are often glabrous beneath. In S. altissima the stem is pubescent to below the middle, usually to the base, but loss or abrasion of the hairs often makes it difficult to discern pubescence toward the base of the plant. The leaves generally are ± pubescent all across the lower surface, as in S. canadensis var. hargeri, and some of the main leaves are more often entire or nearly so than in the distinctly serrate-toothed S. canadensis.