Fragmentation of rhizomes stimulates shoot production. Rhizome length depends on soil fertility and amount of competing vegetation present. Principally pollinated by insects. A prolific seed producer, one plant may produce about 80,000 seeds per year. One of the most abundant colonizers on Mount St. Helens.
Seeds are nondormant and germinate over a variety of temperatures.
Most newly collected seeds germinate within 10 days. Optimum germinating conditions are warm, well-lighted, and humid. Seed hairs or plumes respond to humidity. Increased humidity causes a decreased plume diameter which results in reduced loft. This increases the chance that seeds are deposited in places with moisture adequate for germination.