The other day I received a call regarding an invasive species coming up in someone’s perennial bed among some plants she had received from a friend. But as it often goes, along with the plants we want in our gardens, come plants we don’t want. In this case, the plant she was calling about was Creeping Bellflower or European Bellflower (Campanula rapunculoides).
Creeping Bellflower is a highly invasive flowering species. Ready-to-apply RoundUp is ineffective. Digging it out is relatively ineffective as well, since any little fragment of its taproot left behind will sprout a new plant. The herbicide I have found to be effective is Triamine which I use as a spot-spray.
Creeping Bellflower blooms look similar to the native Harebell or Bluebell Bellflower (Campanula rotundifolia). But, unlike the native species, the 5-petaled violet-blue bell-shaped flowers alternate up one side of its sturdy 3-4′ stem, and it produces new plants from its roots as it creeps along underground. Its serrated leaves have a broad base which narrows to a tip and they seem to stay green all year long. It also reproduces by seed, so there’s a double-whammy in trying to keep it under control.
The much more delicate looking native bellflower’s violet-blue blooms, on the other hand, loosely cluster at the end of the stems, often causing the plant to nod from the weight. The round basal leaves wither early, leaving only stems and blooms near the end of season. The native Bluebell Bellflower or Harebell remains a single plant and reproduces only by seed.
Native American Bellflower (Campanulastrum americanum)
This biennial plant likes moist areas such as woods and wetlands. Its blue blossoms are more wheel-shaped than bell-shaped, and cluster along all sides of its hairy stem. It has a long curving style which protrudes from the creamy-white center ring.