S. altissima has a series of involucral bracts that are usually 3 or 4 mm tall and is hairy all over the underside of the leaves, which sets them apart from S. canadensis, which has shorter involucral bracts and is only hairy on the veins under the leaf. S. altissima also has pubescent stems and no bloom below its flowers, which distinguishes it from S. gigantea, having the opposite features (Native Plant Trust, 2023).
S. arvensis has a flower head over 3 cm wide, which is different from the similar plants S. oleraceus and S. asper, because they have smaller flower heads. Both of these are also annual and from a taproot, which is unlike S. arvensis, since it is perennial from a deep-seated rhizome (Native Plant Trust, 2023).
S. cordifolium is distinguished from S. ciliolatum by its bracteate peduncles, 4 to 8 mm long rays, and anthocyanin-obscured involucral bract tips. S. cordifolium also has its middle and upper stem leaves away from the stem instead of clasping it, and the base of its middle and upper leaves narrow, unlike the similar S. undulatum (Native Plant Trust, 2023).
S. novae-angliae has a mostly green stem, dark blue-purple rays, and leaves that do not clasp the stem, unlike S. puniceum, which has a purple stem, light blue-purple rays, and leaves that can clasp on its stem. S. novae-angliae can also have a capitulum up to 5 cm wide, which is different from both S. puniceum and S. cordifolium, which both usually have a capitulum of less than 4 cm (Native Plant Trust, 2023).
D. tenuifolia is different from D. muralis, because of its fruit being on a stipe and on a 3 cm long pedicel. It also has a firm stem at the bottom. D. muralis has no stipe under its fruit, a 10 to 13 mm pedicel, and a less firm stem base (Native Plant Trust, 2023).
C. rapunculoides can be differentiated from C. latifolia and C. trachelium by its secund raceme and its non-erect calyx lobes (Native Plant Trust, 2023).