Buffalobur (Solanum rostratum)

Flowering annual plants 6 to 12 inches tall as seen in June to August.  Leaves 2 to 5 inches long, alternate, midribs, petioles, and stems very prickly.  Flowers yellow, 5 lobes, 1 to 1 1/2 inches wide.  Fruit in a rough-spiny bar.