Elymus crinitus
| Taeniatherum caput-medusae | |
|---|---|
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Poales |
| Family: | Poaceae |
| Genus: | Taeniatherum |
| Species: | T. caput-medusae |
| Binomial name | |
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Taeniatherum caput-medusae (L.) Nevski |
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Taeniatherum caput-medusae is a species of grass known by the common name medusahead. This aggressive winter annual grass is changing the ecology of western rangelands in North America. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature preserves, and other wildlands. These lands are essential for agriculture and for protecting the integrity of ecological systems. Natural areas contain many nonnative plant species that occur as self-sustaining populations in the lower 48 of the United States, including medusahead. As of 2005, medusahead infested approximately 972,700 acres (3,936 km2) in the 17 western states (from North Dakota south to Texas and west to the Pacific coast), and spreads at an average rate of 12% per year. As medusahead spreads, it can outcompete native vegetation in overgrazed rangelands, reduces land value, and creates a wildfire hazard.
Medusahead was first described in the United States in Oregon in 1903 as Elymus caput-medusae by Thomas Howell. Nevski recommended in 1934 that the Russian types of medusahead should be classified in a separate genus, Taeniatherum. In the 1960s, it was suggested by Jack Major of the University of California that there are three geographic and morphologically distinct taxa: T. caput-medusae, T. asperum, and T. crinitum. After traveling in Russia, Major thought the proper classification for the plant introduced to North America was Taeniatherum asperum. The genus was revised in 1986 by the Danish scientist Signe Frederiksen. He made the previously mentioned distinct taxa into subspecies of Taeniatherum caput-medusae.
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