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

Maps

Invasive Listing Sources

• Arizona Noxious Weeds
• California Invasive Plant Council
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Michigan Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• New Hampshire Invasive Plant Species Watch List
• WeedUS - Database of Plants Invading Natural Areas in the United States

References