Combating Invasive Plants in SoCal
As a part of this year's Plant-a-Thon in late April, Vera Society joined Arroyos & Foothills Conservancy at their monthly habitat restoration day in Cottonwood Canyon. My two daughters joined me at this event to help weed two particular invasive plants: European grasses and black mustard plants. The black mustard plants in particular caught my interest since it has quite pretty little yellow flowers and is easy to spot.
Black mustard plant at Arroyos & Foothills Conservancy habitat restoration day
Over the next couple of weeks it seemed to be everywhere I looked: driving in the Hollywood Hills, near my daughter's school, and generally in undeveloped areas. While out on a run in Hahamonga Watershed Park, I took a picture of a veritable field of it:
Field of black mustard at Hahamonga Watershed Park in May 2025
While native to northern Africa, western and central Asia, and parts of Europe, Brassica nigra (commonly known as black mustard) is considered invasive to Southern California. Black mustard grows profusely in the winter before native plants have taken hold and crowd out them out with their tall stalks, deep system of roots, and production of allelopathic chemicals that prevent germination. The weed dries up by mid-summer and can increase the frequency of fires by acting as kindling.
Case in point, here is a picture from Hahamonga Park in June as the black mustard is beginning to dry out:
Dry black mustard at Hahamonga Park one month later in June 2025
What to do now that it seems to be here to stay in Southern California? Well, one option is to break out the fork and knife! The organization Tree People has a great article discussing the delicacy options of this weed here: https://treepeople.org/2024/06/11/black-mustard/
