Indigobush

Amorpha fruticosa

Indigobush

Family: Fabaceae

Other Common Names: False indigo, ibush, lead plant
Weed class: B
Year Listed: 1988
Native to: Eastern and Central United States
Is this Weed Toxic?:

humans, livestock


Legal listings:

WA Quarantine list, WAC 16-750

Why Is It a Noxious Weed?

Although native to the Eastern United States, in some Western states it is considered invasive and has naturalized. It escapes planted areas and grows along streams and rivers and prairie draws forming dense thickets and outcompetes native species.

How would I identify it?

General Description

Indigobush is a thornless, deciduous, multiple stem shrub that can grow to over 12 feet tall and can form thickets.

Flower Description

Flowers are in dense, upright clusters, in the upper branches. They are blue-violet to dark purple and have 10 stamens.

Leaf description

Leaves are made up of 13 - 25 leaflets which are one to two inches long.  They are gland dotted and hairy with smooth margins.

Stem description

Older stems are woody and younger stems are green and hairy.

Fruit Seed Description

Seed pods are small, curved, dark brown, about 1/4 inch in size and are dotted with glands. Each pod contains 1 or 2 seeds.

Where does it grow?

Indigobush grows in prairies, hillsides, sandy roadsides, along streams and rivers. Please click hereto see a county level distribution map of indigobush in Washington.

How Does it Reproduce?

Indigobush reproduces by seed.

How Do I Control It?

Mechanical Control

Cutting plants may result in re-sprouting stems. Repeated cutting may be used to control seed production each year.

Herbicide Control

Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator.

For More Information

See our Written Findings for more information about indigobush (Amorpha fruticosa).

See this detailed profile for more in depth information about indigobush (Amorpha fruticosa).

Report on Indigo bush from the book "Weed Control in Natural Areas in the Western United States"

Additional Photos