Species: Taeniatherum caput-medusae

Medusahead germinates in the fall. Roots begin to grow immediately and continue to grow all winter. Seed dormancy is due to inhibitory substances in the awns of fresh seed which have been removed by early fall (Nelson and Wilson 1969). Laboratory experiments (Harris 1977) showed that germination may be delayed by dryness and cold temperatures but still occurs sooner than cheat grass and bluebunch wheatgrass. Germination rates increased with increases in temperature and water potential. Harris (1977) also found that speed of germination, percent germination, and winter root growth exceeded that of BROMUS TECTORUM (cheat grass) and AGROPYRON SPICATUM (bluebunch wheatgrass), supplementing earlier studies by Hironaka (1961). In Idaho, it was found that seed viability increased from 12% to 78% from late June to early July and reached a maximum viability by the middle of July (Sharp et al. 1957). Germination rates of 98% have been reported (Murphy and Turner 1959). Germination may be observed within 8-10 hours of moistening, and primary root growth occurs rapidly to 18-20 cm before branching (Harris 1977). <br><br>Harris and Wilson (1970) found that medusahead effectively removed available soil water at depths where A. SPICATUM roots were growing. These characteristics confer an advantage in fall establishment and allows medusahead to compete successfully for soil moisture with B. TECTORUM and, especially, with A. SPICATUM, which is late germinating and slow growing (Harris 1977). <br><br>Seedling emergence and growth were favored in field treatments which included burial in pits and surface burial combined with subsequent soil movement (Evans and Young 1972). Also documented in Evans and Young's study were specific effects of these field microsites on micro-environmental variables important to germination/establishment and comparisons with controlled laboratory treatments. <br><br>Plant density after establishment may range from 500 plants per square foot on scablands to 2000 plants per square foot on valley bottom soils (Sharp et al. 1957). Established populations form stem mats 5-12.5 cm thick which decompose slowly. The dense litter cover enhances medusahead germination, may exclude cheat grass (Harris 1965, Evans and Young 1970), ties up soil nutrients, and contributes to fire danger in the summer (Hilken and Miller 1980). <br><br>T. caput-medusae has root development and anatomy suitable for later reproductive phenology and matures later than other annual species (Harris 1977). Sharp et al. (1957) found that medusahead reaches maturity two to three weeks later than cheat grass. Medusahead requires a cold treatment and possibly a light stimulus after seed germination for seed formation to occur. Medusahead sends up culms with seed heads in May (Lusk et al. 1961) and reaches full flowering by mid-June, about the time that the root system has reached full development (Hironaka 1961). Young et al. (1970) found seasonal, seed source location, garden location, and yearly differences of as much as two to three weeks in the phenology of medusahead. The number of seeds per head ranges from 5.6 in drier areas to 8.7 in wetter ones (Sharp et al. 1957). <br><br>Long distance dispersal is primarily by travel in coats of livestock, especially sheep. Local dispersal from established patches is by wind and water (Furbish 1953). <br><br>Although a few reports indicate that medusahead is palatable in early spring before maturity (Lusk et al. 1961), most grazing animals rarely eat it unless under forced or fertilized grazing conditions. Livestock are often injured by its awns and seeds, and the seeds are least preferred by wild birds (Goebel and Berry 1976).