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.