Not the brightest star
BY THE BLAINE BUG CREW
As you can see, yellow star-thistle is not the kind of star that you want to wish upon. This invasive weed will grow in any uninhabited space. It will also overtake pastures and riverside areas.
This plant likes to grow in large groups so that it can take over more space faster. It reproduces extremely fast, as well. This, as you well know, makes it almost uncontrollable! Plus, the plant is not even pretty to look at. Its poky thorns that extend from under its flower head can make your skin crawl with pain!
Here are some more facts about yellow star-thistle:
Yellow Star-thistle is an herbaceous annual reproducing entirely by seed. A large plant is capable of producing up to 100,000 seeds, which can remain viable in the soil for up to 10 years. In the Pacific Northwest, its flowers bloom from July through October, with seed disseminating by late August.
The bracts of yellow star-thistle are spiny, often exceeding 2 cm in length. The plant produces two types of seeds, both of which are shiny and 0.3 cm long. Plumed seeds are mottled tan and brown in color and occur in the center of the flower head. Non-plumed seeds are black in color and occur around the periphery of the flower head. Stems are winged and typically grow between 60-120 cm tall. Basal leaves are lobed while upper leaves are linear and attach to the stem with wings.
Yellow star-thistle is common in rangelands, along roadsides, and in other disturbed habitats such as hayfields, orchards, vineyards, and abandoned areas. Six insects and one rust have been released as biological control agents for this plant in the Western U.S. that have had varying levels of impact.
If you have yellow star-thistle in an area where there is no grazing, cultivation, mowing or spraying, please call the local Blaine County Bug Crew at (208) 316-0355. Thank you for helping us control Blaine County’s noxious weeds!