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The adenophora project

The adenophora conundrum

Ever since I purchased some 'Adenophora liliifolia' plants from a well-known mail order perennial supplier many years ago, the genus Adenophora has thrown me for a loop. I soon found out that our plants had wickedly wandering ways (I'm still trying to eliminate it from several areas of our garden, with limited success). What I got was probably in fact the notorious Campanula rapunculoides.

That experience made me shy away from adenophoras for years (I did not realize the mix-up until later), but more recently, I decided to try a few different species. None of them are known for spreading by roots, although some do seed to excess. By now, I have blooming specimens of three supposedly different species: A. pereskiifolia and A. polyantha (both from traded seed), and A. confusa (a gift from a friend's garden). It was pretty obvious that A. pereskiifolia was incorrectly named (the leaf shape is wrong), but was it a different species of adenophora? Similarly, are the others correctly named?

Telling adenophora apart from campanula

Meanwhile, I had found what appears to be the standard reference on the web about distinguishing adenophoras from campanulas, the following blurb from the Gardens North catalog:

About 40 species of hardy, summer-blooming plants native to Eurasia and Japan, similar to Campanula because of their nodding, blue, bell-shaped flowers. For full sun or part shade in average garden soils. Adenophora and Campanula are often confused Here is a simple test for distinguishing the two. Take a flower and gently pull 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. An easy way to rogue out all those imposters!

Similarly, the brief Wikipedia page on Adenophora states:

Many of its species are quite similar to species of Campanula, from which they differ only through the presence of a tubular or glandular disc at the base of the style.

So it should be easy to figure out if I have the genus right, right? Well, I tried it out, giving the identification method a go for the 'adenophora' species mentioned above, as well as for several campanulas. The results are shown below, with photos of the flowers in various phases of dissection.

Adenophora confusa

Once the fused petals are removed, you can see the white inner structure, which again has petal-like parts. Pealing those away reveals no bulbous or glandular disc. So it must be campanula.

Adenophora pereskiifolia

Once again, the style emerges from a flat base. That's not a glandular disc, is it? Another campanula, it seems.

Adenophora polyantha

Third strike - I'm out. Same result. Now let's look at some campanulas.

Campanula cochlearifolia

Slightly different attachment of style to base, but basically similar to the 'adenophoras'.

Campanula alliariifolia

No bulbous attachment here either (although I could make an argument for a toroidal object here).

Three weeks later...

An unknown bellflower came into bloom in my sale plot. No sign to say what it was, and it didn't look like anything I've grown before. I took a few pictures, and asked on GardenWeb's Name That Plant forum what it might be — and I learned that it was most likely A. triphylla var. japonica. That made some sense — I had tried to grow that species from seed, in what I believed to be an unsuccessful attempt. Great! Another opportunity to put a plant to the botanical test. Let's see how it worked out:

Adenophora triphylla var. japonica

Wow! So that's what a bulb-like appendage looks like! I was delighted that I finally had examples of both true and false adenophoras. It wasn't until a few years later that I had another species to inspect:

Adenophora stenanthina

A rather different look from the first one, but still an enlarged structure. The rest of the plant is a good match to the species, so I'm fairly confident of its adenophoraness. I'll continue to inspect new species as the opportunity arises.

Adenophora tashiroi?

The flowers looked somewhat like those of my A. stenanthina, so I was convinced I had an adenophora – but wait, there's no bulbous appendage. So it's probably a campanula (still awaiting identification, but at least something more interesting and desirable than C. rapunculoides).

The conclusion

I've proven that nearly all of the plants that came into our garden named 'Adenophora' are in fact campanulas. A fellow gardener concerned about the grand scale at which plants sold or labeled as adenophoras in the US in fact are campanulas struck up an email conversation with me after finding this page. He convinced me that, although my "adenophoras" differ somewhat in their appearances, habits, and invasive tendencies, all of them are the evil Campanula rapunculoides. With the discovery of the stray A. triphylla and the more recent success with A. stenanthina, I'm jubilant that I can now count Adenophora among the genera I've grown. I'll continue my quest for different ones, because this one looks quite different from the campanulas I've grown, and makes a nice addition to our garden. Meanwhile, I hope that this page will be helpful to gardeners on the web as an illustrated guide to making the distinction.

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