The greatest problems come from cut-leafed teasel's aggressive nature. The rosettes crowd out native and established vegetation. Once it is established in an area, it can quickly form large patches. The availability of palatable forage is reduced, domestic animal and wildlife habitat is eliminated, recreational values are lowered, and erosive situations are created. Cut-leafed and common teasel are generally considered to be biennials, although they can complete their life cycle during one season.
Teasels start as a low growing vegetative stage called a rosette.
During the rosette stage it grows a taproot that may be 2 feet deep. If they sprout early enough in the season, a central stalk emerges that may reach 6 to 7 feet tall. Cut-leafed teasel's white blooms are present from July through September. Common teasel is easily separated with their purple to pink blooms seen from June to October. Flowering of either species may be extended if the plants are cut down before the blooms mature.