This North American annual is a remarkably widespread, variable weed (Knapp et al. 2019; FNA 14; W). Flowering plants in Ky. range from 3 cm to 1 m or more tall. It is a native diploid (2n = 24) that is closely related to the Eurasian species, S. nigrum L. (2n = 72). These taxa have often been combined or confused in nomenclature; see keys and citations of Cr and W. Probably all previous reports of nigrum from Ky. should be transfered to emulans. S. nigrum sensu stricto is concentrated in coastal states (K, W), and differs from emulams and americanum as follows (Knapp et al. 2019; FNA 14; W): foliage with glandular trichomes; fresh plants sticky to the touch (versus glandular trichomes abset or few, plants not sticky). inflorescence subracemose, corymbose or umbellate (versus umbellate), pedicels and peduncles becoming stout (versus remaining slender); anthers mostly 1.8-2.6 mm long (versus 1.4-2 mm); berry dull (versus glossy), with sclerotic granules (concretions of stone cells) usually absent (versus usually present); seeds 1.7-2.2 mm long (versus 1.2-1.8 mm). S. americanum Miller (including S. ptycanthum) is a more southern relative on the Coastal Plain. An infamous cultivar in this complex was hybridized partly from the Mediterranean S. villosum Mill. and known as "Burbank's Wonderberry". It was widely promoted and distributed a century ago or more, but Gm just stated: "The berries are edible, if one desires to think so." Leaves of plants in this complex have also been cooked for greens or used for medicine within some cultures, but there is a danger of toxicity from solanine or other alkaloids (Jain et al. 2011). Leaves can also be eaten by generalist mamallian herbivores (pers. obs.).