Texas Blueweed

Helianthus ciliaris

WA A Asteraceae
Data Maturity Baseline

Washington State Classification

Class A — Eradication Required Statewide

Texas blueweed quickly establishes and spreads in disturbed areas and in cultivated fields.

Quick Reference

Type
perennial herb
Origin
Grasslands of south-central and southwestern US and Northern Mexico

Identification

Growth Habit

Texas blueweed is a perennial plant with creeping roots, or rhizomes, which can form extensive patches. The stems and leaves are often blue-green or gray-green in color and grow 1.3 to 2.3 feet (40 to 70 cm) tall.

Leaves

Leave are generally opposite (sometimes alternate) and are attached directly to the stems (sessile). Leaf shape ranges from narrow to very narrow with a tapering base. Leaf margins are wavy, may be toothed and have stiff hairs.

Flowers

Each flowerhead is composed of two types of flowers. The outer ray flowers are yellow and less than 0.5 inches long. The inner disk flowers are reddish to purple brown. Bracts at the base of flowerheads in a few rows, generally with hair on the margins.

Fruit & Seeds

Seeds are smooth and hairless, 0.12 to 0.14 inches (3 to 3.5 mm) long.

Impact

Texas blueweed quickly establishes and spreads in disturbed areas and in cultivated fields. It is unpalatable to livestock and can reduce the grazing quality of invaded fields. It also can significantly reduce crop yields.

Ecology & Spread

Habitat

It grows in cultivated fields, drainage areas, dry lakes and roadsides. Please click here to see a county level distribution map of Texas blueweed in Washington.

Spread Mechanisms

seed vegetative fragments

Reproduction

It primarily reproduces by sending out rhizomes. Rhizome fragments can also sprout new plants. Plants can produce up to 7,500 seeds, but only about 1% germinates. This small number of viable seeds can still help the plant to colonize distant areas.

Regional Notes — Puget Sound

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Control Methods

Mechanical

  • Digging out the plant, making sure to get all of the roots, can be effective at controlling Texas blueweed. Any root fragment left in the soil can sprout into a new plant. It is important to periodically check the controlled area for new plants--growing from either root fragments or from seed. Small populations may also be controlled by covering with a tarp or weed control fabric that blocks out sunlight.

Biological Control

  • None are currently used. Texas blueweed is resistant to the sunflower beetle and the carrot beetle.