Flower profile

Purple bush-bean

Macroptilium atropurpureum

Purple bush-bean (Macroptilium atropurpureum) is a vine in the Fabaceae family, native in the lower 48 states, blooming mostly April–December across the U.S.

Not native to Hawaii

Purple bush-bean is a wildflower that USDA PLANTS lists as native in the lower 48 states.

4states where USDA records it

497HI sightings*

727U.S. sightings*

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

On our lists for: Hawaii

Quick look

Macroptilium atropurpureum, commonly referred to as purple bush-bean, or siratro is a perennial legume recognized by its climbing, dense, green vines and deep purple flowers. The plant is indigenous to the tropical and subtropical regions of North, Central, and South America, as far north as Texas in the US and as far south as Peru and Brazil.
From Wikipedia's article Macroptilium atropurpureum, CC BY-SA 4.0.

It belongs to the Fabaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) / a vine with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 4 states. ^{USDA PLANTS}
NatureServe lists it as not native to Hawaii. ^NatureServe
USDA PLANTS lists its flower color as purple. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as indeterminate. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 4 ft. ^{USDA PLANTS}
iNaturalist has 497 research-grade sightings of it in Hawaii, ranking #100 among the 118 flowers on our Hawaii list. ^iNaturalist

When does it bloom?

Flowering records by month in Hawaii (iNaturalist research-grade observations marked “Flowering”) (31 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
Hawaii: Not listed Not on Hawaii threatened and endangered plants (HAR 13-107; the state list follows the federal list), DLNR Division of Forestry and Wildlife. NatureServe: SNA, not applicable (usually because it isn't native there) in Hawaii. ^{HAR 13-107}
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 peopleNot well documented

None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

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 purple bush-bean in 4 states.

AKMEVTNHWAIDMTNDMNILWIMINYRIMAORNVWYSDIAINOHPANJCTCAUTCONEMOKYWVVAMDDEAZNMKSARTNNCSCDCOKLAMSALGAHITXFL

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, Florida, Hawaii, Texas.

Hawaii counties with USDA records: Hawaii, Honolulu, Maui.

Growing conditions

USDA PLANTS gives Purple bush-bean a medium shade tolerance, medium drought tolerance and low moisture use. It is rated for soil pH 5.0 to 8.0 and winter lows down to 23 °F.

Shade tolerance: Medium
Drought tolerance: Medium
Moisture use: Low
Soil textures it is adapted to: coarse, medium, fine
Soil pH range: 5.0 to 8.0
Minimum temperature tolerated: 23 °F
Frost-free days needed (minimum): 365
Annual precipitation range: 15 to 111 inches
Minimum root depth: 24 inches
Salinity tolerance: Medium
Fertility requirement: Medium
Growth rate: Rapid
Lifespan: Short
Active growth period: Spring and Summer
Fruit or seed: Brown · Year Round to Year Round
Can be propagated by: container, cuttings
Commercial availability: Routinely Available

From the USDA PLANTS characteristics data for MAAT80. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Native status by region (USDA PLANTS): Hawaii: Introduced; Lower 48 states: Native; Puerto Rico: Native.

Other scientific names (synonyms in USDA PLANTS): Phaseolus atropurpureus.

County records: USDA PLANTS lists it in 15 counties across 4 states; the most are in Florida (7), Texas (4), Hawaii (3).

Other Macroptilium on Bloomipedia (1): Phasey bean.

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.

More Hawaii flowers

Sensitive plant

Mimosa pudica

Introduced

🌼 Blooms in HI: February–December

Sensitive pea

Chamaecrista nictitans

Introduced

🌼 Blooms in HI: January–December

Māmane

Sophora chrysophylla

Native

🌼 Blooms in HI: January–December

Sources

USDA, NRCS. PLANTS Database, profile MAAT80.
iNaturalist, Macroptilium atropurpureum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Macroptilium atropurpureum (lead quoted under CC BY-SA 4.0).
Hawaii: Hawaii threatened and endangered plants (HAR 13-107; the state list follows the federal list), DLNR Division of Forestry and Wildlife.
Hawaii: Hawaii noxious weed list (HAR 4-68).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Macroptilium atropurpureum (global and state ranks).
Edibility and toxicity: no source found (marked "not well documented").
Photo: Shaun Case via iNaturalist · CC BY 4.0 · resized.