Appendix L
Maintenance Level Guidelines
Cut-leaved Teasel (Dipsacus laciniatus L.) Common Teasel ( Dipsacus fullonum L .)
DESCRIPTION The plant grows as a basal rosette for a minimum of one year then sends up a tall flowering stalk and dies after flowering. Cut-leaved teasel blooms from July through September, and common teasel blooms from June through October. Flowering plants have large, oblong, opposite, sessile leaves that form cups (the cups may hold water) and are prickly, especially on the lower midrib. Stems also are prickly. Teasel's unique inflorescence makes the plant readily identifiable when blooming. Flowers are small and packed into dense oval-shaped heads. The heads (inflorescences) are subtended by upcurved bracts and are located terminally on the flowering stems. Cut-leaved teasel usually has white flowers, while common teasel usually has purple flowers. Cut-leaved teasel can also be distinguished from common teasel by its irregularly pinnately-lobed upper stem leaves. Upper stem leaves of common teasel have smooth margins. Flowering stems may reach 6-7 feet (1.8-2.1 meters) in height. Cut-leaved and common teasel should be accurately identified before attempting any control measures. If identification of the species is in doubt, the plant's identity should be confirmed by a knowledgeable individual and/or by consulting appropriate books. HABITAT Teasel grows in open sunny habitats, ranging from wet to dry conditions. Optimal conditions seem to be mesic habitats. In Illinois, teasel sometimes occurs in high quality prairies, savannas, seeps, and sedge meadows, though roadsides, railroads, dumps and other heavily disturbed areas are the most common habitats of teasel. LIFE HISTORY A single teasel plant can produce over 2,000 seeds. Depending on conditions, up to 30-80% of the seeds will germinate, so each plant can produce many offspring. Seeds also can remain viable for at least 2 years. Seeds typically don't disperse far; most seedlings will be located around the parent plant. EFFECTS UPON NATURAL AREAS Teasels are aggressive exotic species that have the capacity to take over prairies and savannas if allowed to become established. Lack of natural enemies allows teasel to proliferate. If left unchecked, teasel quickly can form large monocultures excluding all native vegetation. Cut-leaved teasel is more aggressive than common teasel and has severely threatened several northern and central Illinois natural areas.
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464 Naperville Park District | 2023 MASTER PLAN
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