Brassica tournefortii is in the Mustard family. It is native to the desert areas of the Mediterranean region of Europe. It has expanded its distribution in the sandy soils of Los Osos, most probably spread during the sewer project, and can rapidly overtake other plants and form a monoculture.
We are featuring this plant as it is one of two plants being targeted for control by Celebrate Los Osos (CLO), a local non-profit. The other plant is devil’s thorn (Emex spinosa). CLO is sending a postcard showing both plants to every household in the town, with instructions on how to remove the pests. One mustard plant can produce 16,000 seeds. The seeds will mature in the seed pods even if the plant has been pulled, and so control also requires the plants be placed in the trash. We recommend pulling it as soon as flowers appear, which can be as soon as January, and not letting any fruits have a chance to develop. We also recommend using gloves, as the hairs on the leaves could cause some minor skin reaction in some individuals.
Saharan mustard (Brassica tournefortii) is an annual that grows to 2 feet high, branched from base. Leaves in basal rosette, pinnately lobed, serrate-dentate, stiff and hairy. Four flower petals, 4-7 mm long, pale yellow. Fruit spreading to ascending 3-7 cm long, narrowed between seeds.
Leaves image credit: By Mike – Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=3500735
Bloom image credit: By Stickpen – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6229699