Buffalobur

About

A very spiny annual nightshade with bright yellow star flowers and berries sealed inside spiny burs. Native to the western plains, it has become an aggressive weed across much of the country, and its foliage and green berries poison livestock.

Also called buffalo-bur, buffalobur nightshade, spiny nightshade, Colorado bur

How to identify it

Look for

Bushy plants 1/2-3 feet tall are covered almost everywhere with straight yellow spines up to about 1/2 inch long. Leaves are 2-6 inches and deeply cut into 5-7 rounded lobes, prickly on the veins. Yellow flowers about 1 inch across grow in clusters, and each berry is wrapped tightly in a spiny husk.

Look-alikes

Horsenettle is also prickly but has white to violet flowers, shallower lobes and smooth, uncovered yellow berries. Buffalobur seedlings have a clear central vein under the seed leaves and deeply round-lobed young leaves.

Where it grows

Overgrazed pastures, barnyards, fencerows, yards, gardens, roadsides and waste areas, especially in sandy, dry soil.

When

Grows through the warm season and blooms all summer, with spiny burs forming as the flowers fade.

How it spreads

By seed from the spiny burs, which also catch in wool and fur.

Most common in

Where it is regulated

Washington lists buffalobur as a Class C noxious weed and Oregon as a Class B noxious weed; Idaho prohibits it as a noxious weed seed.

What to do, gentlest first

Protect yourself first. Weed killers are a last step; always read and follow the label.

1. Mow before it blooms Prevent

   Mowing close and often, before flowers open, stops seed production and works very well.

2. Hoe or pull before flowering By hand

   Hoeing or rototilling young plants eliminates them. Pull or hoe out plants before the first flowers appear.

   Wear thick gloves.

3. Treat seedlings before bloom Conventional spray

   Glyphosate works in landscape beds and bare ground, and a 2,4-D, MCPP and dicamba mix works in lawns; spray young plants before they flower.

   Read and follow the label. Many lawn weed killers also kill vegetables and flowers, and glyphosate harms any plant it touches.

Uses, wildlife and pets

Pets

Nightshades (Solanum species) are listed by the ASPCA as toxic to dogs, cats and horses; signs include drooling, severe stomach upset, diarrhea, drowsiness, weakness, dilated pupils and a slow heart rate. Sheep, goats, calves, pigs, chickens and ducks can be poisoned, mostly while green berries are on the plant, and the burs lower the value of wool.