Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

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

Cirsium ochrocentrum, Yellowspine Thistle

Ambrosia deltoidea, Triangle-leaf Bursage

Triangle-leaf Bursage has greenish-yellow, dull inconspicuous male and female flowers on the same plants (monoecious). Here male flowers grow terminally on branches, each with its own small stem (peduncle). Ambrosia deltoideaTriangle-leaf Bursage has greenish-yellow, dull inconspicuous male and female flowers on the same plants (monoecious). Photograph shows female flowers (fruits) growing in clusters on lateral axils just below the male flowers. Ambrosia deltoideaTriangle-leaf Bursage has greenish-gray leaves above and whitish below (tomentosa). New leaves have very small whitish hairs; leaf margins are toothed. This species drops its leaves in extreme heat (drought deciduous).Ambrosia deltoideaTriangle-leaf Bursage is a native perennial shrub or subshrub that grows to 2 feet or larger. The plants are greenish-gray (leaves), gangly with slender, often reddish, brittle branches. Ambrosia deltoideaTriangle-leaf Bursage, in the United States, is known only from Arizona but in Arizona it is often a dominant or co-dominant species. This species grows at elevations between 1,000 and 3,000 feet. Ambrosia deltoidea

Scientific Name: Ambrosia deltoidea
Common Name: Triangle-leaf Bursage
Also Called: Triangle Bur Ragweed, Triangle Bursage (Spanish: Chicurilla, Ambrosia, Estafiate, Chamizo Forrajero).
Family: Asteraceae, Sunflower Family
Synonyms: (Franseria deltoidea)
Status: Native
Duration: Perennial.
Size: About 2 feet or larger.
Growth Form: Shrub or subshrub; erect, gangly, somewhat rounded bush with slender brittle branches, new branches with tiny white hairs tomentose, reddish-brown, older branches grayish, dried or dead throughout.
Leaves: Greenish-gray above, grayish-white below; alternate, petiolate shape triangular, new leaves with very small whitish hairs tomentose about an inch long, margins toothed, drops leaves in extreme heat (drought-deciduous).
Flower Color: Greenish-yellow; dull, inconspicuous, flowers borne on a spike-type stalk (inflorescence) both male (staminate) and female (pistillate) flowers (monecious); (inflorescence), male flowers on top with the female flowers below, fruit is a rounded (globose) spiny bur, seed an achene.
Flowering Season: December to April.
Elevation: 1,000 to 3,000 feet.
Habitat Preferences: Rocky hillsides, plains, mesas and sandy washes.
Recorded Range: In the United States, Triangle-leaf Bursage is relatively rare where it is found only in Arizona. It is also native to Baja California and northwestern Mexico. In Arizona it grows in the central, southern and southwest parts of the state.

North America & US County Distribution Map for Ambrosia deltoidea.

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: Triangle-leaf Bursage is one of the most common plants in the lower Sonoran Desert. It is a dominate or co-dominant plant in desert scrub communities especially with Creosote Bush or Palo Verde or alone in a single stand. The type species was collected by Fremont on the Gila River, Arizona.

Triangle leaf Bursage is often used as a nurse plant by the Saguaro cactus. It is reported to have little or no value to livestock and normally lives about 50 years. As is the case for many members of this genus, pollen from the male flowers of Triangle-leaf Bursage causes hay fever in many people.

Also see in Southwest Desert Flora Canyon Ragweed, Ambrosia ambrosioides, White Bursage, Ambrosia dumosa, Hollyleaf Bursage, Ambrosia eriocentra, Burrobush, Ambrosia monogyra and Cheesebush, Ambrosia salsola.

Date Profile Completed: 6/20/2013; Updated, 07/25/2015, updated 01/04/2017
References:
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 deltoidea
1993, The Jepson Manual, Citation: http://ucjeps.berkeley.edu/interchange/I_treat_indexes.html (accessed 06/20/2013)
John L. Strother, FNA | Family List | FNA Vol. 21 |9. Ambrosia deltoidea (Torrey) W. W. Payne, J. Arnold Arbor. 45: 421. 1964.; 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
USDA Forest Service Fire Effects Information System (FEIS). (accessed 06/20/2013) -
http://www.fs.fed.us/database/feis/plants/shrub/ambdel/all.html
SEINet for synonyms, scientific names and recorded geographic locations, http://swbiodiversity.org/seinet/