The status of genera within the family Campanulaceae will undoubtedly be in a state of flux and controversy for the foreseeable future as modern scientific methods expose genetic relationships among taxa which up to now have been grouped by botanists based solely on visible morphological characteristics. (Here is an interesting article about how decisions on botanical reclassification are being made: http://www.rhs.org.uk/Learning/Research/APONAT1.htm.) But for the time being the old names and their claims to generic status - or at least most of them - are still valid, and so they can still be listed as members of the family Campanulaceae.Lobelia - We should get this one out of the way first. Lobelia has always been the odd-man-out in Campanulaceae, being the only member of the family not to have regular flowers but instead generally tubes with the openings being divided into lips, usually grouped two and three. It is highly variable, from small annuals to giant hairy perennial African species that look from a distance like saguaro cactus. Lobelia is probably the base form from which many other lobelioid genera are derived; it is therefore highly paraphyletic and not a good genus. Many general sources (such as encyclopedias) merely say it is "not recognized in all classification systems", and even the Angiosperm Phylogeny Group report of 2003 sidestepped the issue by listing it under both Campanulaceae and Lobeliaceae. Some botanists make the half-step of placing it in sub-family Lobelioideae under Campanulaceae.
Many sources make a point of saying that the genus as a whole has not been studied sufficiently to make a determination. As no member - as currently recognized - is usually considered to be a rock garden plant, perhaps we should just be patient and concentrate on those genera that are.
Symphyandra - This is a relatively small genus of about 14 species which is separated botanically from Campanula only by the anthers, which instead of being free are joined in a tube that surrounds the style. This characteristic, common to other campanulas but only at an early stage, is considered by some not to be sufficient cause for generic separation. An RHS Advisory Panel has already recommended merging it with Campanula.
Symphyandras range from eastern Europe to Korea, flowers are campanulate, often elongated, usually nodding, and purple or white. Typically a basal rosette gives rise to ascending or decumbent stems of 30-60 cm, on the large side for the rock garden. While some are perennial, in practice many act as self-seeding annuals, and others are biennials and even monocarps.
S. hofmannii, pictured, is found in rocky places in countries of the former Yugoslavia. A short-lived biennial, it is 30-60 cm tall, with creamy-white flowers to 3 cm long.
Edraianthus – A small genus of low-growing plants found from the Balkans to the Causacus.
The campanulate blue-violet or occasionally white flowers are usually held in clusters, sometimes held aloft or at the end of splayed stems, as in E. dalmaticus, graminifolius, parnassicus, serbicus and tenuifolius, or virtually obscuring the foliage in a mat of true or almost stemless flowers as in pumilio or serpyllifolius. They prefer full sun and well-drained soil.
The original document is available at http://nargs.org/nargswiki/tiki-index.php?page=Campanulaceae