Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

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

Cirsium ochrocentrum, Yellowspine Thistle

Ambrosia monogyra, Singlewhorl Burrobrush

Singlewhorl Burrobrush has both male and female flowers in the same clusters. Flowers are white or green and most flowers are males. Here are male (staminate) flowers, most buds with just a few fully opened. Ambrosia monogyraSinglewhorl Burrobrush has both male and female flowers in the same clusters. Flowers are white or green and most flowers are males. Here is a small cluster of female (pistillate) flowers recently opened. Ambrosia monogyraSinglewhorl Burrobrush is a shrub or subshrub, new plants green older plants brown or straw colored. Plants are mostly erect and densely branched somewhat broom-like in profile. Note the female flowers in the photograph. Ambrosia monogyraSinglewhorl Burrobrush is a native perennial species that grows in mostly sandy soils especially near rivers or dry river beds. This species grows up to 12 feet in elevations from 1,000 to 4,000 feet. Plants bloom from September to October. Ambrosia monogyraSinglewhorl Burrobrush has green, alternate leaves with rough hairs, threadlike or linear. Plants bloom in the fall from September to October. Plants in the genus Ambrosia are referred to as Ragweed. This species was formerly included in the genus Hymenoclea. Ambrosia monogyra

Scientific Name: Ambrosia monogyra
Common Name: Singlewhorl Burrobrush
Also Called: Burrobush, Burrobrush, Cheeseweed Burrobrush, Singlewhorl Burrobush; (Spanish: Jécota, Jejego, Romerillo).
Family: Asteraceae, Sunflower Family
Synonyms: (Hymenoclea monogyra)
Status: Native
Duration: Perennial.
Size: Up to 12 feet.
Growth Form: Shrub, subshrub; dark brown, brown or straw colored, erect, densely branched, broom-like in profile.
Leaves: Green; alternate, minute rough hairs (scabrous), threadlike (filiform) or linear.
Flower Color: White or green; numerous flowers, most flowers are male (staminate) with single female (pistillate) flowers in the same cluster; fruit a winged fusiform burr; seed is an achene.
Flowering Season: September to October.
Elevation: 1,000 to 4,000 feet.
Habitat Preferences: Mostly sandy soil.
Recorded Range: Singlewhorl Burrobrush is found in the southwest United States in AZ, CA, NM, NV and TX. In the states outside of Arizona it has erratic distribution apparently based on specific habitat requirements. It is marginal in NV. It is also native to Baja California and northwest Mexico. In Arizona it is locally common where found in the central, southern and western parts of the state.

North America & US County Distribution Map for Ambrosia monogyra (as Hymenoclea monogyra).

U.S. Weed Information: No data available.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: In North America Ambrosia monogyra has the following wetland designations: Arid West, UPL; Great Plains, FACW; Western Mountains, Valleys, and Coast, UPL.
UPL = Obligate Upland, almost never occur in wetlands
FACW = Facultative Wetland, usually occur in wetlands, but may occur in non-wetlands.
Threatened/Endangered Information: Listed in California as threatened because of trail usage and non-native plants.

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 Hymenoclea.

Comments: Singlewhorl Burrobrush is a "Burrobrush" that blooms profusely in the fall. It is closely related to Cheesebush, Ambrosia salsola which also blooms profusely but in the spring. Pollen from both species causes hay fever in susceptible individuals. A predominate species where found in Arizona however, in California it is listed as threatened because of trail usage and non-native plants. In appearance it is an unlikely member of the daisy family.

Also see in Southwest Desert Flora; Canyon Ragweed, Ambrosia ambrosioides, Triangle-leaf Bursage, Ambrosia deltoidea, White Bursage, Ambrosia dumosa Hollyleaf Bursage, Ambrosia eriocentra, and Cheesebush, Ambrosia salsola.

Seeds of Singlewhorl Burrobrush were used as a food source by Seris Indians, an indigenous group of the Mexican state of Sonora. See complete species account from Native American Ethnobotany, University of Michigan, Dearborn.

References:
Date Profile Completed: 6/17/2013; Updated, 07/25/2015, updated 01/09/2017
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database, as Hymenoclea monogyra.
Arizona Flora, Kearney, Thomas H., Peebles, Robert H., 1960, University of California Press, Berkley and Los Angeles, as Hymenoclea monogyra.
1993, The Jepson Manual, Citation: http://ucjeps.berkeley.edu/interchange/I_treat_indexes.html (accessed 06/17/2013)
John L. Strother| Family List | FNA Vol. 19, 20 and 21 | Asteraceae |1. Ambrosia monogyra (Torrey & A. Gray) Strother & B. G. Baldwin, Madroño. 49: 143. 2002. Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
Native Plant Information Network, NPIN (2013). Published on the Internet http://www.wildflower.org/plants/ [(accessed 01/09/2017.]. Lady Bird Johnson Wildflower Center at The University of Texas, Austin, TX.
http://www.wildflower.org/plants/result.php?id_plant=HYMO
Wikipedia contributors. "Seri people." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 17 Mar. 2013. Web. 17 Jun. 2013.
Wikipedia contributors. "Hymenoclea monogyra." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 9 Jun. 2013. Web. 17 Jun. 2013.
SEINet for synonyms, scientific names and recorded geographic locations, http://swbiodiversity.org/seinet/
California Native Plant Society - Rare Plant Rank: 2.2 - Rare, threatened, or endangered in California, but more common elsewhere - .2: Fairly endangered in California – http://www.rareplants.cnps.org/detail/3229.html (accessed 1)06/17/2013