Swamp Goldenrod (Solidago patula) is 2½-6 feet tall and usually unbranched, except where the inflorescence occurs. The central stem is light green to purplish green, sharply angled and sometimes narrowly winged, and hairless or nearly so; sparse short pubescence may be present above. Alternate leaves occur along the entire length of the stem, becoming smaller as they ascend upward. The basal and lower cauline leaves are 4-12 inches long and 1½-4 inches across; they are more or less obovate in shape and serrated along their margins, tapering to long winged petioles. The middle to upper cauline leaves are 2-4 inches long and ½-1 inch across; they are elliptic to oblanceolate in shape and slightly serrated to smooth along their margins. The middle to upper cauline leaves are either sessile or they have short winged petioles. The upper surface of the leaves is medium green and either hairless or covered with stiff minute hairs; the lower surface of the leaves is hairless and smooth. Sometimes the basal and lower cauline leaves become greenish yellow or wither away by the time the inflorescence appears. The blooming period occurs from late summer into the fall for about 1-1½ months. The florets are replaced by small bullet-shaped achenes with tufts of hair. The achenes are sparsely hairy; they are distributed by the wind. The root system is fibrous and rhizomatous. Sometimes a small caudex will form on an older plant. Clonal offsets often develop from the rhizomes.
Habitats include typical swamps, sandy swamps, shrubby fens, shaded seeps, sandy pannes and inter-dunal wetlands near Lake Michigan, and bogs. Swamp Goldenrod prefers shaded wetlands where the soil is either sandy or non-sandy; it is usually found in higher quality natural areas.
The preference is partial sun to light shade, wet to consistently moist soil that consists of loam or sandy loam with organic matter. Some plants may lean over to the side if they lack adequate support from adjacent vegetation. A low area that is protected from the wind is desirable.