Plant of the day: field mustard

A pasture is swamped in a sea of yellow. Millions upon millions of flowers cover the hills and flatlands, and straggle over the fenceline into neighboring fields and roadside ditches. This is field mustard–Brassica rapa, also known as common mustard or rape mustard. I have no idea if it is planted deliberately, or if it appears in certain pastures as a result of fertilization, compost, or some other agricultural technique. Whatever the source, it is a striking and dramatic part of the spring landscape throughout coastal California!