Convoluted


Leaf of Milk thistle (Silybum marianum).


 


Milk thistle (Silybum marianum) is an aggressive invasive species not native to California. In Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch) it seems to be increasingly abundant, particularly in the aftermath of the Topanga Fire. Last year, in some areas of Upper Las Virgenes Canyon, it grew thick as corn and more than head high.