Yellow Starthistle
Centaurea solstitialis
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Yellow starthistle is native to the Mediterranean region, but since its introduction to North America in the mid-nineteenth century it has become a large-scale noxious weed. It is extremely invasive and has now dominated over 18 million acres in the United States alone.
Yellow starthistle is a thorny winter annual in the knapweed genus. It is a grayish-green plant with multiple rigid stems that extend in all directions from the base, forming a bushy-looking cluster that can reach two meters in height and more than that in diameter. It produces bright yellow flowers ringed with long, sharp spines. The plant grows quickly and is very competitive. It bears a taproot that can reach a meter deep into the soil, allowing it to thrive during dry, hot summers. It is versatile in its growth patterns, and can adapt to drought or low soil moisture content by producing smaller plants with fewer seeds during dry years. (From Wikipedia)
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Yellow Starthistle rosette
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