black mustard

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

Description from Invasive.org

Appearance

Brassica nigra is an annual plant that can grow 2-8 ft. (0.6-2.5 m) tall, branching occasionally.

Foliage

The leaves are alternate up to 10 in. (25 cm) long and 3 in. (7.6 cm) across, becoming smaller as they ascend the stems. The lower leaves are pinnate and obovate. The upper surface of a lower leaf is often has scattered hairs that are stiff, short, and white.

Flowers

Flowers are in clusters that are 0.5-2 ft. (0.15-0.61 m) long when fully mature. Each flower can be 0.3 in. (7.6 mm) across, consisting of 4 yellow petals. The petals are rounded toward their tips. Flowers are in bloom during the summer.

Fruit

Fruit is about 0.67 in. (17 mm) long and tapering to a conical beak. The seeds are dark brown to black in color with a pungent taste.

Ecological Threat

Brassica nigra prefers disturbed areas including meadows, thickets, areas along railroads and roadsides. It is native to Eurasia.

Selected Images from Invasive.org

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Plant(s) In asphalt crack
John M. Randall, The Nature Conservancy, Bugwood.org
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Flower(s)
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
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Fruit(s)
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
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Seed(s) Seeds in various positions, most with hilar region showing. Note course reticulations (thick veins).
D. Walters and C. Southwick, USDA, Bugwood.org
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Seed(s) Looking down at the hilar region of four seeds. The dark area underneath the whitish funicular remnant is sometimes clearly circular (as in the second seed from the left) and sometimes not.
D. Walters and C. Southwick, USDA, Bugwood.org
Additional Resolutions & Image Usage