Flower profile

Whitethorn acacia

Vachellia constricta

Whitethorn acacia (Vachellia constricta) is a shrub or small tree in the Fabaceae family, native in the lower 48 states, blooming mostly May–August across the U.S.

Native to Arizona

Whitethorn acacia is a flowering plant that USDA PLANTS lists as native in the lower 48 states. In Arizona it's most often seen in bloom in May–August.

5states where USDA records it

1,509AZ sightings*

2,147U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Arizona

Quick look

Vachellia constricta, also known commonly as the whitethorn acacia, is a shrub native to Mexico and the Southwestern United States.
From Wikipedia's article Vachellia constricta, CC BY-SA 4.0.

It belongs to the Fabaceae family. ^iNaturalist
USDA PLANTS describes it as a shrub / a tree with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 5 states. ^{USDA PLANTS}
NatureServe lists it as native to Arizona. ^NatureServe
In Arizona, most iNaturalist sightings of it in flower come in May–August. ^iNaturalist
USDA PLANTS lists its flower color as yellow. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as late spring. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 9 ft. ^{USDA PLANTS}
iNaturalist has 1,509 research-grade sightings of it in Arizona, ranking #61 among the 132 flowers on our Arizona list. ^iNaturalist

When does it bloom?

In Arizona, most flowering sightings come in May–August.

Flowering records by month in Arizona (iNaturalist research-grade observations marked “Flowering”) (79 records)

Conservation status

Federal (U.S. ESA): Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. ^{USFWS ECOS}
NatureServe global: G5 Secure worldwide. ^NatureServe
Arizona: Not listed Not on Arizona Native Plant Law protected plants (Ariz. Admin. Code R3-3 Art. 11, App. A, eff. Feb. 2, 2025). NatureServe: SNR, not yet ranked in Arizona. ^{AAC R3-3 App. A}
Rare elsewhere: No other U.S. state ranks it S1, S2, SH or SX.

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleToxic (slight, per USDA)

USDA PLANTS rates its toxicity as “slight.” (USDA's rating covers people and livestock and doesn't say which parts.) NC State Extension has no page for it. ^{USDA PLANTS}

For petsNot well documented

It isn't on the ASPCA plant list.

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records whitethorn acacia in 5 states.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, Maryland, New Mexico, Texas, Virginia.

Arizona counties with USDA records: Cochise, Coconino, Gila, Graham, Greenlee, La Paz, Maricopa, Pima, Pinal, Santa Cruz, Yavapai, Yuma.

Growing conditions

USDA PLANTS gives Whitethorn acacia a high shade tolerance, high drought tolerance and low moisture use. It is rated for soil pH 7.0 to 8.5 and winter lows down to -13 °F.

Shade tolerance: High
Drought tolerance: High
Moisture use: Low
Soil textures it is adapted to: coarse, medium
Soil pH range: 7.0 to 8.5
Minimum temperature tolerated: -13 °F
Frost-free days needed (minimum): 250
Annual precipitation range: 4 to 20 inches
Minimum root depth: 12 inches
Salinity tolerance: Medium
Fertility requirement: Low
Growth rate: Slow
Lifespan: Moderate
Active growth period: Spring and Summer
Fruit or seed: Brown · Summer to Fall
Can be propagated by: bare root, container, seed
Commercial availability: Field Collections Only

From the USDA PLANTS characteristics data for VACO9. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Other scientific names (synonyms in USDA PLANTS): Acacia constricta.

County records: USDA PLANTS lists it in 37 counties across 3 states; the most are in Texas (17), Arizona (12), New Mexico (8).

Other Vachellia on Bloomipedia (1): Sweet acacia.

More from the Fabaceae family (114 on Bloomipedia; most observed first): Lupines, White clover, Red clover, Eastern redbud, Purple crownvetch, Bird's-foot trefoil, Partridge pea, White sweetclover.

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Sources

USDA, NRCS. PLANTS Database, profile VACO9.
iNaturalist, Vachellia constricta: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Vachellia constricta (lead quoted under CC BY-SA 4.0).
Arizona: Arizona Native Plant Law protected plants (Ariz. Admin. Code R3-3 Art. 11, App. A, eff. Feb. 2, 2025).
Arizona: Arizona prohibited noxious weeds (Ariz. Admin. Code R3-4-245).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Vachellia constricta (global and state ranks).
Edibility and toxicity: USDA PLANTS.
Photo: Luke via iNaturalist · CC BY 4.0 · resized.