Creeping bellflower

Creeping bellflower, Campanula rapunculoides, is a too-vigorous herbaceous perennial native to Europe, Western Asia and the Caucasus. Other common names include creeping bluebell, European bellflower, garden bluebell, June bell, rampion bellflower, and rover bellflower. The leaves, shoots and roots of this plant are edible, and it was once grown for culinary purposes. In Wisconsin it is listed as a "restricted invasive plant." It grows in almost any soil in wet or dry conditions, reseeds readily and spreads by rhizomes and root fragments.
Creeping bellflower produces erect, unbranched green to purple stems 1-3 feet tall. The basal leaves are wider and heart-shaped while the leaves on the stems gradually become shorter and more narrow with shorter (or no) petioles toward the top. The largest leaves are up to 5” long and 2” wide. The opposite foliage is coarse and irregularly toothed, with small blunt teeth. The leaves are dark green on the upper surface and light green below, with short hairs along the underside of the leaf veins. The lavender to purple-blue, bell-shaped flowers bloom from early summer through fall. Peak flowering in southern Wisconsin is in July.  They may occur in dense patches, spreading by short stolons. There are both slender surface roots and deeper, fibrous and bland-tasting, tuber-like roots up to 18” long and about an inch in diameter.
Introduced as an ornamental, creeping bellflower escaped gardens and is now found throughout Wisconsin, invading fields, stream banks, woodlands, prairies, roadsides, urban areas, and oak savannas. It can create monoculture stands through seed production and rhizomes. This species may overwhelm other less vigorous plants. In Wisconsin it is listed as a "restricted invasive plant".
Creeping bellflower is very difficult to eradicate. It is nearly impossible to control it by digging or pulling the roots. Try digging at least 6” deep and several inches out from the plant to ensure you have gotten all of the roots. Repeated pulling or mowing in a growing season will weaken the plant but will not kill it. To attempt chemical control, apply a glyphosate solution using foliar spray or wicking method. Non-selective herbicides, such as glyphosate, can be effective, but it may require several applications to eliminate all the roots. To try to avoid damaging grass, herbicides with dicamba as the active ingredient can be applied.

A first attempt at controlling creeping bellflower was made pulling it by the roots from around iris and other plants it has been starting to overtake.  After allowing time for the remaining roots to sprout again, further attempts at control will be made.