''Ambrosia deltoidea'' is a

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n species of flowering plant in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

known by the common names triangle bur ragweed, triangle bursage, and triangleleaf bursage.

Distribution and habitat

The plant is native to the

Sonoran Desert The Sonoran Desert () is a hot desert and ecoregion in North America that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the Southwestern United States (in Arizona and California). It ...

region of

, where it can be found in

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

Baja California Sur Baja California Sur, officially the Free and Sovereign State of Baja California Sur, is a state in Mexico. It is the 31st and last state to be admitted, in 1974. It is also the second least populated Mexican state and the ninth-largest state by ...

, and

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, with its distribution extending north into

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

.Marshall, K. Anna. 1994
''Ambrosia deltoidea''.
In: Fire Effects Information System, nline U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. This shrub grows in

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

habitat, such as desert

grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes such as clover, and other herbs. Grasslands occur ...

and

shrublands Spring Park is a small area in London, England. It is within the London Borough of Bromley and the London Borough of Croydon, straddling the traditional Kent-Surrey border along The Beck. Spring Park is located north of Addington, London, Adding ...

. It is a dominant or codominant species, and one of the most abundant plants,Bowers, J. E. (2002)
Regeneration of triangle-leaf bursage (''Ambrosia deltoidea'': Asteraceae): Germination behavior and persistent seed bank.
''The Southwestern Naturalist'' 47(3) 449-53. in the Arizona Upland Subdivision of the

. It may occur in upper and lower bajadas, but it is most often found in the

ecotone An ecotone is a transitional area between two plant communities, where these meet and integrate. Examples include areas between grassland and forest, estuaries and lagoon, freshwater and sea water etc. An ecotone may be narrow or wide, and it ma ...

between them. It can be found in open areas. It grows on steep, rocky slopes alongside cacti such as the

saguaro The saguaro ( , ; ''Carnegiea gigantea'') is a tree-like cactus species in the monotypic genus ''Carnegiea'' that can grow to be over tall. It is native to the Sonoran Desert in Arizona, the Mexican state of Sonora, and the Whipple Mountains ...

and paloverde such as the yellow paloverde. Other plants in the habitat include

condalia ''Condalia'' is a genus of Thorns, spines, and prickles, spiny shrubs in the Tribe (biology), tribe Rhamneae of the buckthorn family, Rhamnaceae. It was named for Antonio Condal, an 18th century Spain, Spanish physician. Members of the genus are ...

ocotillo ''Fouquieria splendens'', commonly known as ocotillo, is a plant indigenous to the Mojave, Sonoran, Chihuahuan and Colorado deserts in the Southwestern United States (southern California, southern Nevada, Arizona, New Mexico, Texas), and nor ...

jatropha ''Jatropha'' is a genus of flowering plants in the spurge family, Euphorbiaceae. The name is derived from the Greek words ἰατρός (''iatros''), meaning "physician", and τροφή (''trophe''), meaning "nutrition", hence the common name ph ...

, and prickly pears. The bursage easily invades grassland that has been

overgrazed Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature r ...

. Areas protected from grazing have less bursage.Payne, Willard William 1964. Journal of the Arnold Arboretum 45(4): plate IV (4), figures 30-34
line drawings of ''Ambrosia deltoidea''
figure captions on page 429
/ref>

Description

''Ambrosia deltoidea'' is a

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

growing from a

taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot ...

with many lateral and

adventitious root Important structures in plant development are buds, Shoot (botany), shoots, roots, leaf, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. ...

s. The plant produces many thin branches growing up to about half a meter tall. It generally has many dead branches tangled in the living crown. It is drought-deciduous. The leaves are no more than 2 centimeters long. The branches and new leaves are coated thinly in woolly fibers; the leaves become hairless with age. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a spike of several

staminate The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

flower heads A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

. There are often some

pistillate Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...

heads just below these, with some pistillate heads borne on lateral branches. The fruit is an achene covered in spines. The achenes are usually dispersed when they stick to animals. The plant has been observed to have a lifespan of about 50 years.

Uses

This plant acts as a

nurse plant A nurse plant is one that serves the Ecological facilitation, ecological role of helping seedlings establish themselves, and of protecting young plants from harsh conditions. This effect is particularly well studied among plant communities in xeri ...

for other species, providing shade and increased soil nitrogen for young growing plants. It also protects seedlings from

herbivory A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

. It is the main nurse plant for saguaro in Organ Pipe National Monument. It also serves as nurse plant for yellow paloverde, ocotillo, and some prickly pear species. Most bursage plants are associated with a perennial plant. This plant is not palatable to mammals and it is not grazed by livestock. Airborne

allergen An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response. In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivi ...

s from this plant can cause

contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes ...

in humans.Schumacher, M. J. and N. G. Silvis. (2003)
Airborne contact dermatitis from ''Ambrosia deltoidea'' (triangle-leaf bursage).
''Contact Dermatitis'' 48(4) 212-16.

References

External links

Arizona-Sonora Desert Museum''Ambrosia deltoidea'' — Calphotos Photo Gallery, University of California
*[https://web.archive.org/web/20150911220440/http://www.dendro.cnre.vt.edu/dendrology/syllabus2/factsheet.cfm?ID=762 Virginia Tech vTree Fact Sheet, triangleleaf bursage Asteraceae ''Ambrosia deltoidea'' (Torr.) Payne]
Pollen Library, IMS Health, Triangle Burr-Ragweed (''Ambrosia deltoidea'')
{{Taxonbar, from=Q4741891 deltoidea Flora of the Sonoran Deserts Flora of Arizona Flora of Baja California Flora of Sonora Plants described in 1853 Taxa named by John Torrey