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Medusahead rye (Taeniatherum canput-medusae)
ODA rating: B
USDA Symbol: TACA8
Oregon medusahead rye distribution
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Photo by Jed Colquhoun, Oregon Department of Agriculture
Photo by Bonnie Rasmussen, Oregon Department of Agriculture

Photo by Bonnie Rasmussen, Oregon Department of Agriculture
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Annual; blooms May to June. Grows six to 18 inches tall. Slender annual grass with spikelets in a densely crowded bristly spike one  to four inches long. Leaf blades somewhat rolled, 1/16” wide. Usually found in clayey soils.
Found in virtually every county in the state, medusahead rye demonstrates its negative qualities best on the east side of Oregon where it out-competes other grasses by extracting the majority of moisture well before perennial grasses have begun to grow. Medusahead is rich in silica and becomes unpalatable in late spring as forage for cattle or sheep. Once land is invaded by this grass, it becomes almost worthless, supporting neither native animals, birds or livestock. The stiff awns and hard florets can injure eyes and mouths of grazing animals.  Meduahead rye changes the temperature and moisture dynamics of the soil, greatly reducing seed germination of other species, and creating fuel for wildfires.
Native to Mediterranean region of Eurasia and introduced in the United States in the late 1800s. It is predominant on millions of acres of semi-arid rangeland in the Pacific Northwest.
Distribution in Oregon
The first record of medusahead rye in Oregon was in 1887 in Douglas County.

Biological control
No approved biological control agents are currently available, although two smut diseases that eliminate seed production are being researched.