龙葵（学名：Solanum nigrum），又称乌籽菜、天茄子、牛酸浆、乌甜菜，是茄科茄属植物。

一年生草本植物，全草高30-120厘米；茎直立，多分枝；卵形或长椭圆型叶子互生，近全缘；夏季开白色小花，4－10朵成聚伞花序；球形浆果，成熟后为黑紫色。浆果和叶子均可食用，但叶子含有大量生物碱。龙葵碱经煮仍具毒性。

European black nightshade (Solanum nigrum) or locally just black nightshade, duscle, garden nightshade, garden huckleberry, hound's berry, petty morel, wonder berry, small-fruited black nightshade, or popolo) is a species in the Solanum genus, native to Eurasia and introduced in the Americas, Australasia, and South Africa. Parts of this plant can be toxic to livestock and humans, and it is considered a weed. Nonetheless, ripe berries and cooked leaves of edible strains are used as food in some locales, and plant parts are used as a traditional medicine. A tendency exists in literature to incorrectly refer to many of the other "black nightshade" species as "Solanum nigrum".