| The dormancy and germination requirements of the seeds of coneflower (Rudbeckia montana), paintbrush (Castilleja linariaefolia), cinquefoil (Potentilla pulcherrima), mules-ears (Wyethia amplexicaulis), fairy trumpet (Gilia attenuata) and sticky geranium (Geranium fremontii) collected at 9300' in a silver sage (Artemisia cana) community in Gunnison County, Colorado, were studied. The seeds of G. fremontii, R. montana and P. pulcherrima showed high percentages of germination when tested at room temperature a short time after collection. Wyethia amplexicaulis seeds required stratification (at 5C) followed by germination at alternating temperatures. (The regime used was 12h at 12C and 12h at 25C). Castilleja linariaefolia seeds required stratification (at 5C) followed by germination at 20C, for best results. Gilia attenuata seeds gave higher germination percentages in continuous dark than in continuous light. Neither W. amplexicaulis nor C. linariaefolia seeds had leachable endogenous inhibitors that prevented their germination.Artemisia cana was tested for allelopathic effects on G. fremontii, R. montana and P. pulcherrima seed germination. Sage-leaf water extracts, and water leachates, sage-stem extracts, petroleum ether leaf extracts and volatile leaf compounds were tested for their effects on seed germination. With sage-leaf extracts, R. montana was inhibited most, G. fremontii least, and P. pulcherrima an intermediate amount. With sage-leaf leachates and volatile compounds R. montana was inhibited most, radish (R. sativus) was inhibited least, and P. pulcherrima an intermediate amount. With sage-stem (frozen, green stem) extracts, P. pulcherrima was inhibited slightly more than R. montana. On the average, in their natural setting, R. montana grew farthest from, G. fremontii grew closest to, and P. pulcherrima had an intermediate distribution around sagebrush plants. |
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