This is widespread in southeastern states, and extends north locally to the southern Great Lakes region; it remains virtually unknown in the Ohio Rv. watershed upstream of the Falls. S. clandestinus can be confused with compositus and drummondii, but it is generally considered a distinct species (FNA 25). S. clandestinus tends to occur on drier sites in rocky glades, and is infrequent to absent in old fields or regular roadsides on deeper soils. Compared to compositus and drummondii, the fruits of clandestinus are usually larger (1.5-3.5 mm versus 1-2 mm); pericarps are dry and tight (versus gelatinous and loose when wet); lemmas are usually scabrid to puberulent and opaque (versus glabrous and hyaline). Also, its inflorescences tend to be smaller (4-11 cm x 0.4-3 mm versus 5-30 cm x 4-16 mm) but usually become largely exserted from the sheath (versus remaining largely included).