The goldenrod is a flowering plant in the Family Asteraceae. About 100 species make up the genus Solidago, most being found in North America, and a few from Europe. Many species are difficult to distinguish. Probably due to their bright yellow flower heads blooming around the same time as ragweed, the goldenrod is often unfairly blamed for causing hay fever in humans. In reality, goldenrod pollen is too heavy to be blown far from the flowers.