The Genus Ambrosia
Asteraceae: Daisy Family
Collectively called “ragweeds” or “bursages” these species are distributed in the tropical and subtropical regions of the Americas, especially North America, where the origin and center of diversity of the genus are in the southwestern United States and northwestern Mexico. Though ragweeds are wind pollinated, they have been unfairly demonized as a huge contributor of airborne pollinated. Yes, they are wind pollinated, but they are also pioneer plants that settle down soil, keeping it from being kicked up into the air during windy, allergenic seasons—that dirt that gets kicked up is a mix of many allergens, including ancient pollen. Ironically, ragweeds are also effective against allergies taken as a medicinal tea. So they can help both by keeping the soil stabilized, as well as by being used as a tea for one’s allergies. There are 53 accepted species of Ambrosia.
Butterfly larval hosts for:
Crocale Bordered Patch (Chlosyne lacinia ssp. crocale)
Canyon Ragweed
Ambrosia ambrosioides
Herbaceous shrub up to about 5x5’, though more often about 3-4’ tall and wide. During the growing season these plants have a distinctive, sweet smell. Male and female flowers separate but on the same spike, pretty when viewed closeup. Flowers are followed by small burrs. Plants may go dormant with cold or drought, but are often evergreen.
Full sun to bright shade (best with SOME sun), moderate water, hardy to the teens °F.
Important in the Sonoran Desert as a nurse plant and soil stabilizer. Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae). Larval host for ambrosia beetles, Trypodendron spp, Gnathotrichus spp, Xyleborus spp, and Platypus spp. Seeds eaten by some birds and mammals.
The Akimel O'odham use as an analgesic for menstrual pains and use as a poultice applied to the chest to loosen a cough. The Seri people smoke its dried leaves, and use the roots to make medicinal teas and pigments. As mentioned above, this is used as a medicinal tea for allergies and this species is the favored species for this use.
Ambrosia is Greek for food of the gods, while ambrosioides means like ambrosia.
Found along washes and in canyons from 500-4,000 ft. across the Sonoran Desert and south to Durango, along with south into Baja California and into Chihuahua.
Ambrosia bryantii
Baja Bursage
This plant almost looks like a small cholla from the distance. Small, spiny shrub usually less than a foot tall and spreading a few feed wide. The spines come from the fruits. When the plant dies and breaks apart the seed spreads about and comes into contact with the soil. Few plants have spiny fruits but those that do shed the fruits to attach to an animal or something for dispersal. This is the only spiny fruited plant that retains the fruit indefinitely. Short lived perennial.
Full sun, low water when established, hardy to about 25°F. This winter-growing species is from Baja California (they get their precipitation in the winter) so that is when you water it, though be careful of over-watering it. In the summer when it is dormant, splash the plant and soil just a tad once a month or less.
Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae).
Ambrosia is Greek for food of the gods, while the species, bryantii, is named after Marvin P. Bryant, who pioneered studies on syntrophic methanogenic associations.
This unusual bursage is found in the Sonoran Desert in Baja California on rocky, usually volcanic soil.
Sonoran Bursage
Ambrosia cordifolia
Medium shrub with silvery new growth and leave undersides, growing typically 3-4’ tall and as much as 5. Yellowish green flowers in late winter through spring followed by velcro-like burrs. Plants send up new stems after blooming, and are mostly semi-deciduous, but sometimes appear evergreen in cultivation. Drought deciduous.
Full to part sun, moderate to low water when established, hardy to about 15°F.
Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae). As with many bursage species, this plant is important in stabilizing soils and providing as nurse plants for cacti and other plants.
Ambrosia is Greek for food of the gods, while cordifolia means heart-shaped leaves, which is vaguely the overall shape of the leaf, though the margins are ragged.
Found in canyons, arroyos, and on rocky slopes from 1,500-3,500 ft. in southern Arizona, south into Sonora and Sinaloa, Mexico.
Triangleleaf Bursage
Ambrosia deltoidea
Small shrub, 2x2’, separate female and male flowers appear on the same spike (male flowers on top, bur-like female flowers below). Small burs follow flowers. Plants are mostly evergreen.
Full sun, moderate to low water, hardy to about 20°F.
Important pioneer of xeric soils, nurse plant for many other species growing in the low desert. Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae). This plant is not palatable to mammals and it is not grazed by livestock. Seeds are sometimes eaten by birds and mammals.
Ambrosia is Greek for food of the gods, while deltoidea means triangular, like the fourth letter of the Greek alphabet, delta.
Found in sandy washes, on alluvial plains, on gravelly or rocky slopes from 1,000-3,000 ft. abundantly in Arizona and northwestern Sonora, but also in California and Baja California.
Ambrosia dumosa
White Burrobush
Small shrub to about 2x2’, foliage is gray when older. New growth or well-watered plants are more greenish. Can flower almost any time of year with greenish/yellowish blooms followed by small burs. Mostly evergreen.
Full sun, moderate to low water, hardy to 10-15°F.
Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae). Pioneer plant for disturbed sites. White burrobush is an important browse species in the Sonoran Desert, particularly during drought conditions when other more palatable species are not available. Many desert rodents, including kangaroo rats, black-tailed jackrabbits and sheep are known to feed on burrobush seeds, as well as granivorous birds.
Ambrosia is Greek for food of the gods, while dumosa means bushy or shrubby.
Found on dry, fine soils of alluvial plains and slopes below 3,000 ft. in southern UT; south to southeastern California and south into northwestern Mexico.
Ambrosia monogyra
Burrobush
Broomy shrub growing about 5x5’. Drought deciduous. Fall produces small greenish-white flowers. Papery, winged capsules follow. Can colonize in sandy washes. This plant is also known as Hymenoclea monogyra.
Full to part sun, moderate to low water, hardy to about 15°F.
Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae).
Seeds of Burrobrush are used as a food source, and as a remedy for abdominal pains by the Seris.
Ambrosia is Greek for food of the gods; monogyra is from mono-, one and gyra, circle or revolution, referring to the single ring of bracts on the fruit.
Found on floodplains and along arroyos and washes from 1,000-4,000 ft. in Arizona, New Mexico, southwestern Texas; south to central Mexico.
Ambrosia salsola
Cheesebush
Broomlike shrub, 3x3’. Spring blooming with white flowers followed by papery winged fruits. This plant is also known as Hymenoclea salsola.
Full to part sun, moderate to low water, hardy to about 15°F.
Pioneer plant on disturbed soils. Larval host plant for the bird dropping moth (Ponometia erastrioides), and some geometer moths (family Geometridae).
The Seri use cheesebush twigs and stems in several remedies. The twigs or leaves are mixed with all-thorn (Koeberlinia spinosa) twigs, boiled, and the tea taken to treat skin rashes. Seri also drink the tea to relieve pain in the lungs and trachea, and to reduce swelling. Additionally, they use this species as a remedy for rheumatism.
Ambrosia is Greek for food of the gods; salsola comes from the Latin salsus for salty.
Found along sandy washes and on rocky slopes, rarely in saline soil below 4,000 ft. in southern Utah, Arizona, and southern California; south into northwestern Mexico.