About Streptanthus flavescens Hook.
Streptanthus flavescens, which has the synonym Guillenia flavescens, is a mustard plant species that belongs to the Brassicaceae family. It is counted among several species that share the common name yellow mustard, though the species most widely recognized as yellow mustard is likely Sinapis alba. S. flavescens is an annual herb with a thin stem. It produces large, lobed or toothed leaves that grow up to 22 centimeters long around its base, while smaller leaves with less pronounced toothing grow along its stem, which ranges in color from gray-pink to brown. Cream, yellowish, or very pale purple flowers grow at intervals along the upper stem. Each flower is roughly cuboid in shape and around one centimeter long. The petal tips around the flower mouth are curled, flared, or claw-like. The plant's fruit is a thin silique that can reach up to 9 centimeters in length. This species is endemic to California, where it grows in the valleys and mountains surrounding the San Francisco Bay Area.
