butterfly bush

Buddleja davidii

   

Family: Buddlejaceae

Other common names: summer lilac, orange eye; genus also spelled Buddleia

Weed Class: B

Year Listed: 2005

Native to: China

Toxic: not known to be

additional photos

 

   

Why is it a noxious weed?

It forms dense thickets, especially along river banks and gravel bars, which crowd out native plants and may alter soil nutrient concentrations. This shrub is difficult to control, can produce seeds during its first year and seeds are viable 3 to 5 years.

How would I identify it?

General Description: Butterfly bush is a deciduous shrub with arching branches that can reach 15 feet in height. The showy flower spikes are often purple, and the leaves and stems are typically hairy.

Flower Description: Flowers have 4 petals, and are commonly purple with an orange center, but cultivars can be pink, orange, and white. Flower spikes are upright or nodding, reaching a length between 4 to 10 inches. They are fragrant and blooming begins in mid-summer.

Leaf Description: Leaves are opposite, lance-shaped, or egg-shaped. They are up to 10 inches long and 1 to 3 inches wide. They are green to blue-gray above and whitish below due to fuzzy hairs. Leaf have either short stalks are attached directly to the stem (sessile).

Stem Description: Young stems are green. Mature stems develop scraggly, gray-brown bark that peels off.

Fruit/Seed Description: Seeds are held in brown capsules and are small and winged. Plants produce copious amounts of lightweight seed that are wind dispersed. One cultivar produces an estimated 40,000 seeds per flower head.

May be confused with:

How does it reproduce?

Plants reproduce by seed. The germination rate of several cultivars is greater than 80%, with one cultivar producing 92% viable seed. Butterfly bush can also reproduce vegetatively, as cut stems can sprout roots and grow into new plants.
 

Where does it grow?

While often planted in yards and gardens as an ornamental, butterfly bush can colonize disturbed areas including roadsides, abandoned railroad tracks, pastures, riverbanks, and recently logged forests. Please click here to see a county level distribution map of butterflybush in Washington.
 

How do I control it?

General Control Strategy

Flower heads should be cut off before seeds form. Carefully dispose of cut branches, since they can sprout basal roots. There are many suitable alternatives for butterfly bush, please see our latest publication of Garden Wise for more information.

Mechanical Control

Seedlings can be hand-picked and adult plants can be dug up. However, butterfly bush thrives in recently disturbed areas, so be aware that these methods of removing plants may actually promote the growth of new seedlings. Deadhead flower spikes before they produce seed to prevent further spread.

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 butterflybush (Buddleja davidii).
See our postcard for early detection information about butterfly bush.

Additional Photos


 
 

Butterfly bush flowers

Butterfly bush infestation

seedling

butterfly bush in bloom

inflorescences

opposite leaves, undersides whitish with fuzzy hairs

developing seed

developing fruit and old flowers

developing seed capsules

    

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