LIFE HISTORY AND EFFECTS OF INVASION

The teasel population has rapidly expanded in the last 30 years. Movement has been documented along highway systems, where dispersal is aided by mowing equipment. Teasel is an aggressive exotic that forms extensive monocultures.

Teasel produces an abundance of seeds. A single teasel plant can produce over 2,000 seeds; up to 30-80% of the seeds may germinate. Seeds may remain viable for at least 2 years. Seeds typically don't disperse far; most seedlings will be located near the parent plant. However, highway mowing equipment and inappropriate disposal of dried teasel heads from flower arrangements can increase the spread. Dead adult plants leave a relatively large area of bare ground formerly occupied by their own basal leaves, providing an optimal nursery site that new plants readily occupy. Seeds may be water-dispersed, which allows dispersal over longer distances. Immature seedheads of cut-leaved teasel are capable of producing viable seed.