Introduced during early settlement, this virtually ineradicable annual has become a pervasive weed across North America on damp rich soil in woods and fields. In the central Bluegrass, Short (1828-9) noted: "In this locality it prefers rich woods or cultivated places, frequently covering patches of considerable extent." S. media is tetraploid with reported 2n = 40, 42 and 44: a "very polymorphic species, varying in size, habit, pubescence, petal length, stamen number, and seed size and surface detail" (FNA 5). Some Ky. plants in cool damp fertile urban settings are unusually robust, with largely sessile leaves and short petals. Colls. filed under media also need to be rechecked for pallida and neglecta; see notes under those names. Those two species are closely related diploids (2n = 22) that are easily overlooked (Salisbury 1974, FNA 5, Y, W and cited literature). There is no evidence of interbreeding among these three species.