Sahara mustard

Annuals; densely hirsute proximally, glabrescent distally. Stems usually branched basally, (widely) branched distally, (1-) 3-7(-10) dm. Basal leaves: (rosettes persistent); petiole (broad) 2-10 cm; blade lyrate to pinnatisect, 2-30 cm × 10-50 (-100) mm, (margins serrate-dentate), 4-10 lobes each side. Cauline leaves sessile; blade (reduced in size distally, distalmost bractlike), base tapered, not auriculate or amplexicaul. Racemes not paniculately branched. Fruiting pedicels widely spreading, 8-15 mm. Flowers: sepals 5-4.5 × 1-1.5 mm; petals pale yellow, fading or, sometimes, white, oblanceolate, 4-7 × 1.5-2(-2.5) mm, claw 1-3 mm, apex rounded; filaments 2.5-4 mm; anthers 1-1.3 mm; gynophore to 1 mm. Fruits (shortly stipitate); widely spreading to ascending (not appressed to rachis), torulose, cylindric, 3-7 cm × 2-4(-5) mm; valvular segment with 6-12(-15) seeds per locule, 2.2-5 cm, terminal segment 1(-3)-seeded, (cylindric, stout), 10-20 mm. Seeds light reddish brown or black, 1-1.2 mm diam.; seed coat prominently reticulate, mucilaginous when wetted. 2n = 20.

Flowering Feb-Apr. Roadsides, waste places, old fields, washes, open desert areas intermixed with desert shrubs; 0-800 m; introduced; Ariz., Calif., Nev., Tex., Utah; Europe; Asia; Africa; introduced also in nw Mexico, Australia.

Brassica tournefortii was first reported from California (Imperial, Riverside, and western San Bernardino counties) by W. L. Jepson ([1923-1925]), with the first collections appearing from southern California in 1941 (R. C. Rollins and I. A. Al-Shehbaz 1986), Arizona in 1959 (T. H. Kearney and R. H. Peebles 1960), Nevada in 1977, and Texas in 1978 (D. E. Lemke and R. D. Worthington 1991).