A widespread, rapidly growing summer annual weed with opposite leaves and many small, flowers per plant. Many branched plant reaches 2 ft. in height. Flowers appear from summer through frost. Each flower has 4 to 5 toothed white petals surrounding a disk of tiny yellow flowers. Stems and leaves are covered with coarse, dense hairs. Leaves are coarsely toothed, egg to triangular shaped. Re-seeds prolifically. Seeds germinate from early spring through summer, with seedlings emerging starting in late spring and maturing quickly so that several generations occur in a season. Shallow roots make it easy to pull. Native to Central to South America.