Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Ambrosia ambrosioides, Canyon Ragweed

Canyon Ragweed or Big Bursage is a native perennial that may grow up to 6 feet or more in a season. In the southwest it grows at elevations up to 4,500 feet. Ambrosia ambrosioides Canyon Ragweed is a tall subshrub or shrub with multiple stems with bristly white hairs and reddish-brown stems. Stem scars are quite typical. Ambrosia ambrosioides Canyon Ragweed has alternate, lanceolate or narrowly triangular dark green leaves. Leaves are dramatic looking, up to 8 inches or more long, hairy and sticky with sharply toothed margins. Ambrosia ambrosioides Canyon Ragweed has dull yellow or yellowish-green inconspicuous male and female flowers on the same plants. Here male flowers grow terminally on branches, each with its own small stem (peduncle). Ambrosia ambrosioidesCanyon Ragweed has dull yellow or yellowish-green inconspicuous male and female flowers on the same plants. Female flowers grow in clusters on lateral axils just below the male flowers. Here is the developing fruit, a young green bur, from a female flower. Ambrosia ambrosioides

Scientific Name: Ambrosia ambrosioides
Common Name: Canyon Ragweed
Also Called: Ambrosia Bursage, Ambrosia Leaf Bur (or Burr) Ragweed and Big Bursage (Spanish: Chicura).
Family: Asteraceae, Sunflower Family
Synonyms: (Franseria ambrosioides)
Status: Native
Duration: Perennial.
Size: Up to 6 feet.
Growth Form: Subshrub, shrub; tall, erect to sprawling, multiple stems, bristly white hairs, stems reddish-brown, stem scars typical.
Leaves: Dark green, dull; up to 8 inch, petiolate, mostly alternate, lanceolate or narrowly triangular; margins sharply toothed, hairy and sticky.
Flower Color: Dull yellow or yellowish-green; inconspicuous, male and female flowers; inflorescence a spike on terminal or lateral flower heads, fruit is a small fusiform burr with spines and hooks.
Flowering Season: March to May.
Elevation: Up to 4,500 feet.

Habitat Preferences: Riparian areas, dry arid areas, sandy and gravelly river bottoms.

Recorded Range: Canyon Ragweed is relatively rare in the United States occurring in California but mostly in Arizona. It is also native to southern Baja California and Mexico. In Arizona, Canyon Ragweed is found in central, southern and western parts of the state.

North America & US County Distribution Map for Ambrosia ambrosioides.

U.S. Weed Information: No data available.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: No data available.
Threatened/Endangered Information: No data available.

Genus Information: 25 species in Ambrosia throughout the United States and Canada. 15 species in Arizona which now includes members of the former genus Hymenoclea. Plants in the genus Ambrosia are referred to by the common name Ragweed. This species was formerly included in the genus Franseria.

Comments: Canyon Ragweed is limited in distribution in the United States to Arizona and California. It is common throughout much of Arizona but is limited to San Diego County in California. Canyon Ragweed is one of several Ragweed species whose pollen causes hay fever and allergies in some people.

Also see in Southwest Desert Flora Triangle-leaf Bursage, Ambrosia deltoidea, White Bursage, Ambrosia dumosa, Hollyleaf Bursage, Ambrosia eriocentra, Burrobush, Ambrosia monogyra and Cheesebush, Ambrosia salsola.

Ambrosia ambrosioides has been used as an analgesic for respiratory problems by Western American indigenous peoples.
Pima Drug, Analgesic; Decoction of crushed roots taken by women for pains and menstrual hemorrhage.
Pima Drug, Cough Medicine; Poultice of warmed leaves applied to the chest to loosen a cough.
See ethno-botanical uses at Native American Ethnobotany, University of Michigan, Dearborn.

Date Profile Completed: 8/8/2012; Updated, 07/25/2015, updated 01/04/2017, updated format 10/08/2017
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database
Arizona Flora, Kearney, Thomas H., Peebles, Robert H., 1960, University of California Press, Berkley and Los Angeles, as Franseria ambrosioides
The Jepson Manual, Citation: Wed Aug 8 13:17:05 2012
John L. Strother, FNA | Family List | FNA Vol. 21 | Asteraceae | Ambrosia, Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
SEINet for synonyms, scientific names and recorded geographic locations,