Spikeweed

Centromadia pungens

Asteraceae (Sunflower family)

Class C Noxious Weed

Local Control

Spikeweed is a late season annual, native to dry grasslands of central California. Introduced to southeastern Washington within the last century, it is a prolific seed producer and agricultural pest in Franklin County, invading roadsides, field edges, moist waste areas, low alkaline sites and rangeland.

Spikeweed can grow 3 feet tall or more depending on moisture availability. It is rigid with a sprawling appearance. Its leaves and flower bracts are spine-tipped. Large plants can produce more than 100 flowerheads. Rosettes bolt in spring, then produce yellow ray and disk flowers in summer. Seeds fall near the parent plant and can be dispersed by wind or maintenance equipment. 

Spikeweed competes with desirable plants and crops. Because it forms spiny, dense stands it can impede the movement of livestock and wildlife. 

There is only one known spikeweed infestation in Franklin County. If you find this species in Franklin County, please notify the weed board.