Invasive Plant Guide: Perennial Pepperweed
Perennial Pepperweed Flower
- Flower color: white, in dense clusters near the ends of branches
- Flowers: June to August
- Plant height: one to six feet
- Leaves: lanceolate, bright green to gray green, smooth to toothed margin; basal leaves larger than upper leaves
- Fruit: two-seeded capsule
- Seeds: reddish-brown, round, flat, slightly hairy, and about 1/16 inch long
- Growth habit: perennial
- Grows in waste areas, wet areas, ditches, roadsides, croplands, along waterways, and dry habitats such as road cuts and fills.
Robust, deep-seated spreading roots and numerous seeds make this plant very difficult to control. Outcompetes native vegetation and crops. Attempts at mechanical removal spreads the plant by distributing seeds and dividing the rhizomes. An effective method of control is early detection and manual removal. To treat established populations, apply thick mulch mats and manually remove juvenile plants.
Plant is spreading downriver and has been seen with heavy infestations in Seiad Valley, and smaller patches have been noted in Happy Camp. Now is the time to prevent this weed from staking its claim downriver.
- California Department of Food & Agriculture