Ambrosia confertiflora - DC.

Common Name

Slimleaf Bursage

Family

Asteraceae

USDA hardiness

8-11

Known Hazards

Reported traditional food use but likely unsafe.

Habitats

Found on floodplains, desert washes, roadsides, pastures, and disturbed ground.

Range

Native to southern Arizona, New Mexico, Texas, and northern Mexico.

Edibility Rating

(1 of 5)

Other Uses

(0 of 5)

Weed Potential

Yes

Medicinal Rating

(0 of 5)

Care (info)


Richard Spellenberg Creative Commons Attribution-Share Alike 3.0

Richard Spellenberg Creative Commons Attribution-Share Alike 3.0

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Summary

Ambrosia confertiflora, known as slimleaf bursage or weakleaf bur ragweed, is a desert plant with a controversial history as a food source. Though Native Americans reportedly relied on the roots in times of scarcity, the plant contains bioactive compounds that may cause harm, and its edibility remains questionable. The roots are starchy and palatable, yet their toughness and possible toxicity cast doubt on their value as food. Today, slimleaf bursage is primarily recognized as a weedy, aggressive colonizer of rangelands, not as a foraging resource. While it may once have filled an emergency role in desert diets, it is best approached with caution and not recommended as a modern edible.

Physical Characteristics

Ambrosia confertiflora is a PERENNIAL growing to 1.5 m (5ft) by 1 m (3ft 3in) at a medium rate.
See above for USDA hardiness. It is hardy to UK zone 9 and is not frost tender. The flowers are pollinated by Wind.
Suitable for: light (sandy) and medium (loamy) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.

UK Hardiness Map US Hardiness Map

Synonyms

Heterotypic Synonyms: A. caudata (Rydb.) Shinners. Franseria caudata Rydb. Franseria confertiflora Rydb. Franseria hispidissima Rydb. Franseria incana Rydb. Franseria pringlei Rydb. Franseria strigulosa Rydb. Franseria tenuifolia var. tripinnatifida A.Gray.

Plant Habitats

Edible Uses

Reports indicate that the roots of slimleaf bursage were once used as food by Native Americans, particularly the Tohono O’odham, who gathered them in bulk during autumn rains. The roots have a starchy, somewhat resinous flavor, reminiscent of potatoes and sunflower seeds with a faint cardboard-like accent. Boiling does not soften the tough inner cores, but the thin, chewable outer layers provide nourishment. Cooking water takes on the same starchy–resinous flavor and can be used for broths [2-3]. However, serious caution is advised. The plant contains compounds such as confertiflorin, reynosin, and parthenolide, which can cause contact dermatitis, mouth ulcers, and loss of taste. Very little modern research confirms the safety of consuming these roots, and their near disappearance as a food source may indicate either health risks or impracticality [2-3]..

References More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

None Known

References More on Medicinal Uses

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Other Uses

None Known

Special Uses

References More on Other Uses

Cultivation details

Ambrosia confertiflora (weakleaf / denseflower ragweed) is a coarse perennial to subshrub, commonly 0.5–1.5 m tall and in good sites up to about 2 m, often forming broad clumps 0.5–1 m across or more in dense stands. Like other ragweeds, it is a classic anemophilous (wind-pollinated): separate male heads release copious pollen into the air; the small, hidden female flowers are adapted to catch airborne pollen rather than attract insects. A perennial that grows primarily in the subtropical biome. An Annual to short-lived perennial, adapted to zones 8–11. Thrives in desert and semi-arid climates. Sun: Requires full sun. Soil: Tolerates poor, sandy, rocky, or disturbed soils. Moisture: Drought-tolerant; responds to seasonal rainfall, especially late summer–autumn rains. Growth Habit: Upright to sprawling herb/shrub, often forming dense colonies. Habitat: Native to southern Arizona, New Mexico, Texas, and northern Mexico. Found on floodplains, desert washes, roadsides, pastures, and disturbed ground. Often occurs in large stands, resulting in abundant roots that are considered usable.

References Carbon Farming Information and Carbon Sequestration Information

Temperature Converter

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Plant Propagation

Seed.

Other Names

If available other names are mentioned here

Ambrosia confertiflora (Slimleaf Bursage / Weakleaf Bur Ragweed)

Native Range

Arizona, California, Colorado, Kansas, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southwest, New Mexico, Oklahoma, Texas, Utah

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it's worth checking.

High weed potential. Slimleaf bursage is a native species but behaves aggressively, forming vast colonies that dominate disturbed or overgrazed landscapes. Considered a weedy native and often undesirable in rangelands.

Conservation Status

IUCN Red List of Threatened Plants Status : Not available

Related Plants

Latin Name	Common Name	Habit	Height	Hardiness	Growth	Soil	Shade	Moisture	Edible	Medicinal	Other
Ambrosia artemesiifolia	Roman Wormwood, Bitterweed, Blackweed, Carrot Weed, Hay Fever Weed, Stickeweed, Tassel Weed, Wild Ta	Annual	0.9	4-8	M	LMH	SN	M	2	3	1
Ambrosia trifida	Giant Ragweed, Great ragweed, Texan great ragweed, Bitterweed, Bloodweed, Buffalo Weed, Horse Cane	Annual	2.0	1-11	M	LMH	SN	M	1	3	1

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

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