Buffalo Bur (Kansas Thistle)
Taprooted annual with stems completely covered with sharp bristles. Flowers single from upper leaf axils, bright yellow, about 1 inch across with 5 united petals, forming a 5-pointed star with 5 anthers protruding; the lowermost anther is elongated like a beak. The calyx is almost concealed by bristles. Blooms May–October. Leaves alternate on spiny stems, deeply lobed almost to midrib, the main lobes further lobed. Fruit a globe-shaped berry entirely covered by bristles that adhere to animals.
Similar species: There are 13 species in the genus Solanum recorded for Missouri. One is the common garden tomato, S. lycopersicum.