Brassica nigra (L.) W.D.J. Koch

Black Mustard

Herb

Annual

Vascular

Black Mustard is an introduced annual in the Mustard family (Brassicaceae). It is believed to be native to southern Europe and Asia. It has been cultivated for thousands of years for its seed which are used as a spice. In Alabama, it has been found as a sporadic weed on roadsides, in fields, and along railroads. It is an annual with a tap root. Stems are 2-8 feet tall and may be branched above the middle. The stems are pubescent, especially towards the base. Leaves are basal and cauline. The basal leaves are petiolate, obovate in outline, pinnately lobed, and larger than the cauline leaves. The cauline leaves are petiolate or sessile, the base not auriculate or amplexicaul (clasping or wrapping around the stem). The cauline leaves are ovate to elliptic in outline, and less deeply divided than the basal leaves. The leaves are pubescent with stiff hairs, especially on the upper surface. Flowers are produced in racemes. Each flower has four dark yellow petals. The fruit is a silique (a dry dehiscent fruit which is more than 3 times as long as broad. The outer walls of the fruit (valves) split off leaving the seed exposed on a papery septum.) The siliques are erect and more or less appressed to the rachis. Each fruit has 4-12 dark brown or black seed. The seed coat is coarsely reticulate.--A. Diamond

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Not Native GNR (Global Rank)

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