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
• New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture,  Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
• WeedUS - Database of Plants Invading Natural Areas in the United States