We wrote a post a few weeks ago about the hills “yellowing up” with wild mustard. Indeed they are, but there has been some confusion about distinguishing wild mustard from Bermuda buttercup (Buttercup oxalis), another invasive exotic wildflower that blooms at the same time, in similar locations, and has about the same bright yellow color.

Bermuda Buttercup

Bermuda buttercup is found throughout California up to elevations of about 8,200 feet. Like wild mustard, it’s typically found around agricultural land and other disturbed areas as a common weed. The flowers grow up to 20 in a cluster, with each flower comprised of five yellow petals. Their shamrock-like leaves are made up of three perfectly heart-shaped leaflets connected at their points. It is often called sour grass because of the sour-tasting stem. Like all oxalis species, this plant contains oxalic acid, which can be toxic if eaten in large quantities. Therefore, we recommend only very light munching on oxalis for a trail snack.

Finally, just to add more complexity to the issue of identification, despite being called Bermuda buttercup, it is not even in the buttercup family (Ranunculaceae).

Wild Mustard

Wild mustard (Brassica juncea) also has vibrant yellow flowers that grow in clusters. The key to correct identification is in the petals. Mustard flowers only have four flower petals. These edible beauties do not contain toxic compounds and have been an important part of the human diet since the Bronze Age. Several common dinner vegetables, including cabbage, broccoli, cauliflower, Brussels sprouts, and collard greens, are all cultivars of this single species.

Don’t let a field of yellow flowers fool you. Take a closer look at these wildflowers and test your knowledge.

Invitation to Submit Photos

If you have photos of wildflowers that you would like to share with us, please email them to julia@mobileranger.com and we will try to include them in our upcoming wildflower post.