Medusa Head


Noxious winter annual to 0.6 m tall. Medusahead typically invades rangeland communities. Dense stands often develop, displacing desirable vegetation and wildlife, and lowering the livestock carrying capacity. Relative to other forage species, medusahead contains much silica, making it harsh and unpalatable to livestock except during the early growth stages. The stiff awns and hard florets can injure eyes and mouths of grazing animals. Seed-eating birds usually avoid feeding on the seeds. Senesced plants form a dense layer of litter that decomposes slowly, changing the temperature and moisture dynamics of the soil, greatly reducing seed germination of other species, and creating more fuel for wildfires. Medusahead matures 2-4 weeks later in the season than most other annual grasses. The yellowish-green sheen of dense stands is highly visible after other annual grasses turn brown. Introduced from Europe. The western U.S. endemic crown rot fungus (Fusarium culmorum) is a potential biocontrol agent adapted to dry soils.

Depending on timing, intensity, and other factors, controlled burns may reduce or enhance infestations. Slow hot burns initiated when other vegetation has dried and medusahead seeds have not matured (~ 30% moisture content), can reduce infestations significantly. Discing or plowing before seed-set can greatly reduce stands.