Bladder Senna

Colutea arborescens

Bladder Senna

Family: Fabaceae

Weed class: monitor list
Native to: North Africa and Europe

Why Is It a Noxious Weed?

This plant is on the monitor list - it is not a listed noxious weed in Washington. Please contact its sponsor Marty Hudson at to report locations or for more information.

How would I identify it?

General Description

Bladder senna is a deciduous shrub that grows up to ~13 feet (4 meters) tall.

Flower Description

Flowers are in clusters (racemes) up to 5 inches long and are generally comprised of 6-8 flowers. Flowers are yellow to deep yellow and up to 3/4 inch (2 cm) long.

Leaf description

Deciduous leaves are alternately arranged and compound, up to 6 inches long and sparsely hairy. Leaflets range from 7-13 and are oval to broadly oval and have smooth margrins.

Fruit Seed Description

Flowers develop greatly inflated seed pods that are typically up to 3 inches (5-8 cm) in length.

May Be Confused With

Colutea x media, which is a hybrid between Colutea arborescens and Colutea orientalis, produces orange-brown flowers to 3/4 inch, somtimes flushed yellow in the center. Colutea orientalis produces copper-red flowers 1/2 inch long with yellow markings.

Where does it grow?

So far in Washington, bladder senna is known only to occur in 3 counties: Klickitat, Okanogan and Spokane. Bladder senna is also noted to be invasive in some upper Midwest states in the U.S. It can be found growing in woodlands, disturbed areas, grasslands and roadsides.

For More Information

Additional information at the UW Burke Herbarium's image collection page on bladder senna.

Invasive Plant Atlas information on bladder senna.

Additional Photos