For lovers of the prickly vegetable, the presence of groves of wild artichokes, as we have in the Valley of the Moon, might seem like an indication of paradise. In addition to being delicious, artichoke flowers are beautiful, fragrant, and attract bees.
However, the wild cynara carduncula is a fearsome invasive plant.
According to the California Invasive Plant Council, the thistle was probably imported from Europe in the early 19th century as a food plant. It becomes invasive when it escapes cultivation and begins to reproduce from seed. Darwin found it growing in the Argentine pampas in 1889 in an area of “hundreds of square miles.”
At its worst, the “edible thistle” forms thickets that are impenetrable by humans or animals and that shade out native plants. As they develop tap roots eight feet deep and produce seed banks that endure for five years, they are very difficult to control.
More info at this link:
UPDATE SEPTEMBER 2021-Someone, probably Caltrans, has eradicated all the cardoon along the sidewalk north of Sunnyside. They probably used Roundup. I have no doubt that the “forest” will be back this winter, because that lot is full of seeds, some of which could have been there for five years and still be viable.