Often forms dense stands, with stems up to 2 m tall; very conspicuous along roadsides and railroads; often in forests, especially clearings, openings, edges, and old roads; fields, fencerows, and thickets; shores and swamp borders; often thrives after some disturbance. Perhaps more frequent in drier open habitats, especially northwards, than S. lanceolata.

The width of the free part of the staminodium is variable, but usually broader than in S. marilandica (in which it seldom exceeds 1 mm). Both species bear a large number of flowers over a long blooming season (some flowers open while others have formed mature fruit). Hence, it may be difficult to determine that S. lanceolata is an earlier-blooming plant, the first flowers appearing in May or June, while in S. marilandica they usually appear in July or August (though at least one collection, from Lenawee Co., bloomed the last week of June).