The American nightshade (Solanum americanum) belongs to Solanaceae (the Nightshade family). It is an annual herb that is native to North America, and introduced into Japan after World War 2. This herb grows in forest edges and fields, much-branched and can reach 20-30 cm in height. From July to September, it blooms pale purple or white flowers with a diameter of 2 to 5 mm. There are 1 to 4 flowers, and they gather at one point. This herb looks like black nightshade, but varies according to slender stem, narrower leaf and glossy fruit.