Adenophora and its "Evil Twin" revisited

Campanula rapunculoides (Anne Larson photo)

Mystery, intrigue, mistaken identities—who would think such drama could be found in the gentle art of gardening? When it comes to assessment of Ladybells (Adenophora sp.) and rampion or creeping bellflower (Campanula rapunculoides), however, the plot is thick with confusion, suspicion and fear of invasion.

Both plants are in the Campanula family. Adenophora, such as species liliifolia and confusa, are considered well behaved, long blooming and carefree, adding their bluish racemes of bell-shaped blooms to the garden in June and lasting into fall. The “Evil Twin,” as Cold Climate Gardening writer Kathy Purdy refers to it, is C. rapunculoides, a European import that can run through the landscape at will, reproducing both by fine roots and by seed.

On the surface, the two plants may appear identical. Both have heart-shaped basil foliage growing from one to three feet tall. The leaves at the base are up to 5 inches long and 2 inches wide, toothed and opposite; leaves become progressively smaller with shorter petioles higher on the stem.

What further clouds the picture is that in some cases, plants commercially available as Adenophora are actually C. rapunculoides. Dr. Thomas Lammers, a campanula expert at the University of Wisconsin-Oshkosh, claims he has yet to find a true Adenophora in the horticultural trade (e-mail, 7/30/09); all he has found appear to be C. rapunculoides.

Visit several horticultural discussion boards on-line, and you’ll see the vehemence evoked by the spreading habit of the oft-misidentified plant. Stories of entire gardens eaten up by a “gift” of the “Evil Twin” abound; descriptions of futile attempts to eradicate the plant are common, whether it be digging, pulling or chemical warfare. Fine roots that break off easily and are then able to produce new growth surround the fleshy taproot. According to one source, the leaves, shoots and roots of this plant are edible, and it was once grown in Europe for culinary purposes.

Adding to the lore surrounding rampion bellflower is its namesake fairytale “Rapunzel.” While true rampion ("rapunzel" in German) is an annual (Campanula rapunculus) formerly grown as a root crop in Europe, the rampion bellflower name ramains associated with the Evil Twin. According to Susan Mahr of the University of Wisconsin-Madison, “In that story [Rapunzel’s] father steals a rampion plant from a witch’s magic garden to aid his wife in childbirth, and as punishment Rapunzel is exiled to a tower.” Many gardeners may wish they could exile C. rapunculoides to a tower, or at least some remote location off their property.

How is one to know that they are purchasing a true Adenophora and not the thug often confused with it? To a trained eye, the key is found at the base of the flower just above the ovary. Dr. Lammers says that Adenophora has a cylindrical or tubular, 2 to 4 mm long “nectary” or “glandular disk” surrounding the base of the style, within the dome-like structure formed by the triangular bases of the five stamens. This structure is found atop the ovary—C. rapunculoides does not have this structure. Dr. Lammers continues that “In fact, the genus name ‘Adenophora’ means ‘gland bearer’ and was bestowed in reference to this conspicuously large nectary gland.”

Gardens North website suggests that gardeners can identify their plants by taking a flower and gently pulling off the petals, leaving the style standing in the center. You will be left holding the base of the flower with a bumpy appendage (the ovary) in the middle and the style sticking straight up out of the center. VERY CAREFULLY peel off the outside of the bumpy appendage, leaving the style standing. If underneath, all you see is a flat base to which the style is attached, then you have a Campanula. If, however, you see, after the peeling, another bulb-like appendage surrounding the style, then you have an Adenophora.

If you aren’t up to pulling flowers apart to examine their identities, there are some common sense approaches to adding the long-blooming beauty of Adenophora to the garden. First, purchase plants from a reputable source. Additionally, if you uncertain whether the Ladybells is definitely the less-invasive Adenophora, plant it in a pot and place the pot in the ground to contain the root system.