I have been running into a barricade trying to research if in fact there are two genus of ferns, one known as Microsorum and one known as Microsorium with an "i". I can find primarily the genus Microsorum on TROPICOS (Missouri Botanical Garden). Only a few plants are listed as Microsorium sp. But on the International Plant Names Index (IPNI), ePIC (Royal Botanical Garden Kew) and eFloras I find a reasonable number of each. If there is a botanist specializing in ferns reading this board can you elaborate? Are there two genus and if so what are the major differences? Specifically, what characteristics determine which genus a fern then becomes a part? Many horticulturalists put plants such as Microsorium musifolium in the genus Microsorum and vice verso. The same is true of Microsorum thailandicum.
If you search for Microsorum on IPNI and follow the second link (APNI), it returns a page with the following "Remarks: See paper by M.T.M.Bosman, Taxon 35 (1986) 590-591 `Original Microsorum vs. later Microsorium'." I don't know if you can access the article, but Mr. Bosman clarifies that the original publication of Microsorum in 1833 is the correct one and that the spelling Microsorium, published by Link himself in 1841, is an error (he used both spellings in the same publication). Since then the mistake has been used frequently, but authorities like Angiosperm Phylogeny Website, RHS and GRIN use the original Microsorum. Microsorium is just a misspelling of the same plant name.
Thanks Eric! This has been quite confusing and your explanation helps a lot. Still, seems curious to me that major institutions still use the misspelling! Thanks again! Steve Lucas