LARAMIE, Wyo., April 21 -- The University of Wyoming issued the following news release:

Palmer amaranth and other weedy species in the amaranth family pose a growing threat to agricultural operations across the West, with a new invader -- waterhemp -- first documented in Wyoming last summer.

Seven amaranth species, including both native and nonnative species, have been observed in Wyoming so far. As agricultural weeds, redroot pigweed, Palmer amaranth and waterhemp are the most concerning, a recently updated University of Wyoming Extension bulletin reports.

Weedy amaranth species thrive in agricultural settings, roadsides and other disturbed areas. Their aggressive spread is aided by prolific seed production, which allows them to outcom...