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Ecology and Management of Medusahead (Taeniatherum Caput- Medusae Ssp

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Ecology and Management of Medusahead (Taeniatherum Caput- Medusae Ssp Great Basin Naturalist Volume 52 Number 3 Article 6 12-18-1992 Ecology and management of medusahead (Taeniatherum caput- medusae ssp. asperum Melderis) James A. Young Agricultural Research Service, U.S. Department of Agriculture, Reno, Nevada Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Young, James A. (1992) "Ecology and management of medusahead (Taeniatherum caput-medusae ssp. asperum Melderis)," Great Basin Naturalist: Vol. 52 : No. 3 , Article 6. Available at: https://scholarsarchive.byu.edu/gbn/vol52/iss3/6 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 52(3), pr. 245-252 ECOLOGY AND MANAGEMENT OF MEDUSAHEAD (TAENIATHERUM CAPUT-MEDUSAE SSP. ASPERUM [SIMK.] MELDERlS) ABsn\Acr.-Medusahead is nnother in the extensive list of annual herbaceous S],X-"Cies to invade thl:: tempemte desert rangelands of the Great Basin. Mednsahead is not preferred by large herhin)res and apparently is not preferred by gmnivores. Herbage ofthis anlllial gl'ass enhances ignition and sprei.ld ofwildFIres. Mcdwmhcad is highly competitive with the se<..--dlings of IlJltive spedcs and is prohably the greate..<>t threat to the biodiver.<iity uf the natural vegdation that has yet been accidentally introduced into the Great 8nsin. Despite the obvious hiological disruptions that are os.rociated with medusahead invasion, the species offers a wealtll of opportunities for stlldents to examine the mechanism by which thiS species is so sllccessful. Students ofevolution, plant phYSiology, and ecology may find this species to be an excellent model for colonization. Key words: rnedflSahead, "r:lenintherum caput-medusae, armual grass, r,oltmizing species, Wild/ires, grtJZing. In the management of natural resources cies, there has heen confusion about the correct there are certain problems that by their persis­ scientific taxon for mcdusahead. The first tence, magnitude of ecological disruption. and deSCription ofmedusahead in a North American economic impact refuse to dissipate as a result /lora used the taxon EllfrntlS caput-medusae L. of being ignored and neglected. Unfortunately (Howell 1903). There is apparent agreement for range management, medusuhead that medusahead is a member of the tribe (Taeniathemm caput-medusae [L.] Nevski) is Triticeae ofthe grass family There is also appar­ that type of problem. DUring the 1950s ent agreement among morphologists and cyto­ medusahead was considered among the most geneticists that medusahead does not fit in the pressing problems on the rangelands ofCalifor­ genus Ellfrrms. Various authors have placed rna, Idaho, and Oregon. A greatdeal ofresearch medusahead in Hm-dell1H or Hmuely-mus. effort was devoted to solving themedusahead evski (1934) proposed that medusahead was problem. Valuable information was learned truly a different genus and published the name about the ecophysiology and synecology of Taeniathemm Jack Major of the University of medusahead. Control methods were developed CaWarnia suggested in 1960 that material intro­ using herbicides. The fatal link in integrated duced to the United States was Taeniatherom programs for the suppression of medusahead asperom (Major et al. 1960). Based on the populations proved to be mtificial revegetation European and Russian literature, Major technologies after medusahead was controlled. reported that Taetliatherurn contained three The nature of the sites infested had more to do geographic and morphologically distinct taxa, T with this failure than the weed itself, especially caput-medusae, T asperum, and T. crinituUl. in the Intermountain are.:'1. The recent discovery These three species are found in the Mediterra­ of medusahead in northern Utah has renewed nean region and extend eastward into central interest in suppressing this nmgeland weed. Asia. After examining the European material, My purpose in this review is to refresh our collective memories about medusahead ecology gmwing in plac:e. Major decided the United and management. States introduction was 1: asperum. The Danish scientist Signe Frederiksen TAXO:-JOMY revised the genus in 1986. He kept the same three taxa, but reduced them to subspecies of As is often the case with an introduced spe- Taeniatherum caput-medusae. Positive identifi- 245 246 GREAT BASIN NATURALIST [Volume 52 cation to the lowest level possible is absolutely south of Steptoe Butte (Sharp and Tisdale essential for any proposed biological control 1952). Fred Renner told Jack Major hehad seen program for medusahead. According to medusahead near Mountain I-lome, Idaho, as FredeIiksen's revision, subspecies cnnitum has early as 1930, and Lee Sharp bad reports from a very strict spike. Subspecies caput-medusae ranchers that the species occurred in Idaho as has a large open spike with straight awns. The early as J942. The medusahead infestation in spike of subspecies asperl11n is intermediate Idaho increased to 30,000 acres by 1952. Min with angled awns. Subspecies asperurn is the Hironaka estimated that 150,000 acres were only one of the three with pronounced barbs infested by 1955, and the Bureau ofLand Man­ coated with silica on the awns. Apparently, the agement estimated 700,000 acres were infested correct taxon fiJf the medusahead of western by 1959. At that rate of spread it appeared that North America is Taeniatherurn capui-medt.&wJ.e all of Idaho would be infested by the end ofthe ssp. asperum (Simk) Melderis (Frederiksen next decade. The spread ofmedusahead slowed 1986). and nearly continuous infestations remained TaeniatllRrurn caput-medusae ssp. caput­ confined to Gem, Payette, and \iVashington medusae is mostly restricted to Portugal, Spain, counties in southwestern Idaho. There were southern France, Morocco, and Algeria. It has several spot infestations in surroundingcounties been collected outside this area in Europe and (llironaka and Tisdale 1958). Asia, but FredeJiksen considers it adventitious Medusahead spread south in California to in these areas. Subspecies crinitum is found Santa Barbara on the southern coast and Fresno from Greece and Yugoslavia eastward into Asia. County in the intelior valleys. The rapid spread Subspecies asperurn completely overlaps the from southwestern Oregon through northern distribution of the other two subspecies. All and central California occurred in annual-dom­ three subspecies integrate with each other. inated grassland, oak (QuemlS) woodland. and Apparently only the one subspecies occurs in chaparral communities. These areas have a North AmeJica. Does this indicate one or very Mediterranean type climate with hot, dry sum­ limited introductions? mers and cool, moist f~llls, winters, and springs. Medusahead is predominantly self-polli­ Germination occurs in the fall and flowering nated. Genetically the genus appears to stand and seed set in the spring. alone in genomic relations within the Triticeae In northeastern California, east ofthe Sierra (Schooler 1966, Sakamoto 197:3). Apparently Nevada-Cascade rim, mcdusahead invasion T'aeniathenl1n has a genome that is distinct, but occurred at a much slower rate. In the Pitt River hrintly related to those of Psathyrostachys, drainage, vegetation is an intergrade ofOregon Dasypyn.tm, Ercrnopyntm, or HordEUm. white oak (Quercus garryana) woodlands, (Frederiksen and Bothner 1989). cismontane California species, western juniper (juniperus occidentalis), ponderosa pine (Pi.nus HISTOHY IN NOHTH AMERICA ponderosa) woodlands, and sagebrush (Artemi­ sia)/bunchgrass communities rnore typical of Medusahead was first collected in the the Intermountain area. United States near Roseburg, Oregon, on 24 Medusahead was discovered in the Great June 1887 by Thomas Jefferson Howell (1903). Basin at Verdi, Nevada, in the early 1960s. Iso­ It was next collected near Steptoe Butte in east­ lated infestations were subsequently found ern Washington in 1901 by George Vasey (Piper along the eastern front of the Sierra Nevada in and Beattie 1914), followed by a collection near areas where range sheep bands used to concen­ Los Gatos, California, in 1908byCharles Hitch­ trate while waiting for mountain summer pas­ mck (Jepson 1923). Medusahead certainly tures to be free ofsnow. attracted the noted agrologist. McKell, Rohin­ Innortheastern California in the Great Basin son, and Major (1962) commented on this during the early 1960s, there were two small strange initial distribution reaching 390 miles infest;:ltions in city lots in Susanville and a small north and 450 miles south from the point of infestation at the old sheep-shearing site of initial collection. Early herbarium specimens Viewland along the railroad above Wendel, Cal­ show a rapid spread to the south into California. ifornia. Another isolated infestation occurred at J. F. Peehanec made the first collection in the mouth of Fandango Pass in Surprise VaIley. Idaho in 1944 near Payette or about 180 miles By the early 1970s, medusahead was nearly 1992] ECOLOGY AND MANAGEMENT OF MEDUSAHEAD 247 continuous over about 60,000 acres of the seeds touching a mOisture-supplying substrate. Willow Creek-Tablelands northeast of Susan~ In this situation, germination of medusahead ville. Currently, after four years of extreme seeds is controlled by the relative humidity drought, medusahead
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