Ragweeds are in the Ambrosia genus in the aster family. There are about 50 species of ragweed. Most grow in the desert areas of the American Southwest and Mexico. Some species have been spread around the world, where they are now invasive species. The common name is based on the fact that the leaves may look ragged. The genus name of Ambrosia means “food of immortality.” The two most common species are the common ragweed, Ambrosia artemisiifolia, and the giant ragweed, Ambrosia trifida. Artemisiifolia means that the leaves look like leaves of plants in the genus Artemisia, and trifida indicates the leaf often has three lobes.
Some ragweed species are annuals, some are perennials and some are shrubs. The two most common ragweeds are annuals that grow in poor soils in full sun to part shade and don’t need a lot of rain or fertilizer to grow well. They often grow where other plants don’t, such as along railroads or in gravel pits. They can be seen growing right next to each other. Common ragweed grows up to 5 feet tall, and giant ragweed can grow over 15 feet high.
