Other Common Names: blueweed, yerba parada
Weed class: A
Year Listed: 1988
Native to: Grasslands of south-central and southwestern US and Northern Mexico
Is this Weed Toxic?:
not known to be
Why Is It a Noxious Weed?
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.
How would I identify it?
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.
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.
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.
Stems grow upright to spreading along the ground with upright tips. Generally blue-green in color, stems are hairless and may have a whitish, waxy coating (glaucous).
Fruit Seed Description
Seeds are smooth and hairless, 0.12 to 0.14 inches (3 to 3.5 mm) long.
Where does it grow?
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.
How Does it Reproduce?
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.
How Do I Control It?
General Control Strategy
The best strategy to control Texas blueweed may be to deplete the plant's energy reserves by constantly pulling and digging it, in combination with the use of herbicides and the planting of native perennial grasses.
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.
In its native habitat, Texas blueweed grows among other grassland species and does not aggressively outcompete the other plants. The planting of perennial grasses around a Texas blueweed infestation may provide competition for the weed.
None are currently used. Texas blueweed is resistant to the sunflower beetle and the carrot beetle.
For More Information
See our Written Findings for more information about Texas blueweed (Helianthus ciliaris).