Scientific Name: Ambrosia artemisiifolia
Common Name (s): Common Ragweed

Photos by Kayla Sayre, Bella Vista POA Fisheries & Water Quality Sr. Technician

Identification:

Common ragweed is in the Asteraceae family, the second-largest family of flowering plants. It is in the genus Ambrosia, composed solely of ragweed species. Ragweed species originated in the United States, where this genus holds the largest diversity. Species in this genus are monecious, meaning they can only reproduce by pollination and cannot self-pollinate like some other flowering plants. They have inflorescences, or flower clusters, that are spiked in shape with smaller flower spikes around the base. Another common species in this Genus is Giant Ragweed (A. trifida).

Common ragweed reaches heights up to three feet tall. It has extensively branched stems that come from the central stem in an opposite formation. The hairy branching stems are green, and the central stem is green with purple splotches. The leaves are six inches long and four inches across at the base. The leaves have a broad base, tapering toward the tip, and deep lobes throughout. Newer leaves have hair, while older leaves are without hair. The upper stems of the plant terminate into cylindrical, yellow-green, spiked flowers that are under an inch in length. Additionally, they have smaller spiked flowers that cluster around the base of the terminal flower.

Range:

Common ragweed is native to the continental United States and most of Canada.

Ecology:

The flowers on common ragweed do not have petals but spiked, cylindrical clusters. Ragweed flowers bloom between July and October. Male ragweed plants produce abundant, fine pollen, which quickly spreads by wind. Common ragweed produces numerous seeds that remain viable for five or more years in the soil.

Common ragweed has a prolific distribution in low-nutrient habitats. It often prefers sterile soils such as gravel, clay, or sand because of reduced competition with other plants. It prefers direct sun and is drought resistant. It does well in disturbed habitats with newly uncovered dirt. Common ragweed can be found in upland prairies, margins of developed land, roadsides, fences, railroad tracks, weedy meadows, abandoned fields, croplands, vacant construction lots, and waste areas. Along with its survival in rough habitats, common ragweed has allelopathic properties and inhibits the growth of nearby plants, which is problematic in the agriculture industry. Some cohorts of common ragweed have developed glyphosate resistance in the United States.

Common ragweed pollen and seeds have ecological value as a food source for insects, birds, and some mammals. The pollen is dense and fine, so many insect pollinator species enjoy this plant. It is also a host plant to the brown ambrosia aphid (Uroleucon ambrosiae), ragweed plume moth (Adaina ambrosia), and buffalo treehopper (Stictocephalla bisonia). The numerous seeds of common ragweed are rich in oils and are a prominent food source for upland game birds and songbirds. Since the elevated seedheads can remain above the snowline, these seeds are also a viable winter food source. Some voles and ground squirrels eat the seeds. Most herbivorous mammals avoid common ragweed due to its sour taste, but elk and domestic goats are known to eat it when food resources are scarce.

Special Notes:

Common ragweed is everywhere in Bella Vista and is most prominent along roadsides, construction lots, and other low-nutrient, disturbed habitats with direct sunlight. Interestingly, like other members of the Asteraceae family, common ragweed can be used in the phytoremediation of soil contaminated with lead and other heavy metals.