Spikeweed
Centromadia pungens
Washington State Classification
Class C — Widespread, County-Selected Control
Spikeweed is an agricultural pest in the Columbia Basin (southeastern Washington), forming dense stands.
Quick Reference
Identification
Growth Habit
Spikeweed is an annual that grows 3.9 inches to 47.2 inches (10 to 120 centimeters) tall. It has rigid branches and leaves with spreading to stiff hairs. Leaves and flowerhead bracts are spine-tipped.
Leaves
Lower leaves are divided into narrow, linear lobes or 2 times divided. The upper leaves are linear and spine-tipped. Upper leaves may be bearing axillary leaf bunches. Leaf margins are sometimes hairy and midribs are sometimes bristly.
Flowers
Numerous small flower heads of yellow ray and disk flowers. Bracts at the base of the flower head (the involucre) partially covered by upper leaves. Bracts are spine-tipped and have short stiff hairs.
Fruit & Seeds
Achenes (seeds) are around 0.08 inches (2 mm) long
Impact
Spikeweed is an agricultural pest in the Columbia Basin (southeastern Washington), forming dense stands. It is also avoided by livestock.
Ecology & Spread
Habitat
It grows on roadsides, disturbed areas, open +/- alkaline flats, depressions, seasonal wetlands, grasslands, saltbush scrub and cultivated fields. Please click here to see a county level distribution map of spikeweed in Washington.
Spread Mechanisms
Reproduction
Spikeweed is an annual and reproduces from seed.
"
Control Methods
Mechanical
- Hand pulling spikeweed may be effective for small populations. Pulling plants in the spring is best while the plant is still relatively soft but gloves should still be worn.