Dispersal and Germination Dynamics of Broadleaf Filaree, Erodium botrys (Cav.) Bertol 1

Erodium species are important forage plants in the western United States, Australia, and other areas with similar climate. Knowledge of the germination and seedbed ecology of Erodium species will aid in efficient management of rangelands where these annuals occur. Dispersal, self‐burying, and seed germination of the indehiscent fruits of broadleaf filaree ( Erodium botrys (Cav.) Bertol.) were investigated. Field dispersal and laboratory germination in relation to temperature and germination enhancement experiments were conducted. The complex fruit consists of an indurate tipped corpusculum that contains the seed; the spirillium (coiled portion of the awn); and the flagellum (hairlike terminal of the awn). The three parts are a highly efficient mechanism for self‐burial. Indehiscent seeds are impermeable to water at first. This hard seed dormancy breaks during the summer in a natural seedbed condition, but persists if the fruits are stored under dry conditions. The natural mechanism of breaking dormancy involves mechanical action of the fruit breaking the hilum of the seed. The dormancy can be overcome artificially by soaking fruits in concentrated sulfuric acid or by exposing the seeds to diurnal fluctuations of temperature and relative humidity. Artificial hourly temperature fluctuation will accelerate the breaking of dormancy. Seeds that will imbibe water have an optimum germination at relatively cool temperatures, but considerable germination occurs with warm day temperatures and extreme diurnal fluctuations.