Probably no group of modern ferns or fern-like plants as poorly understood as the Ophioglossales. Interpretations of the fertile segment (sporophore) and the unusual stele (eustele?) have troubled botanists for many years. Even the relationships of the order as a whole are in doubt. At the genus and species level, there has been little agreement, and the taxonomy still up in the air. E. P. St. John (1949) grappled with some of these problems and gave a theory to explain them, based upon the subterranean gametophyte, which he believed inhibits hybridization and outcrossing. He stated that hybridization, or even cross-breeding within the species, almost impossible and that as a result, the species tend to be very widely distributed. One of the outstanding peculiarities of this group of plants, he wrote, is that while they are of world-wide distribution the number of species very small. Local endemics may be geographic variants of other species. According to St. John, the species of the Ophioglossaceae are closely related, and the course of evolution usually indicated by transitional and juvenile forms. Through selfing of the subterranean gametophytes a trivial variation may form a colony, and such divergent forms might persist so long as they meet minimum requirements for survival. Now, over a third of a century after St. John's interesting proposals, we question a number of his points on the basis of many new data. We find no evidence that subterranean gametophytes inhibit hybridization and outcrossing. Indeed, 17 hybrids are known in Lycopodium, 1 in Psilotum, and 12 in Botrychium (Wagner et al., 1985) plus two additional Botrychium hybrids described belowall taxa with subterranean gametophytes. The idea that the species of Ophioglossales are generally widely distributed not supported by the data; only a few have truly broad distributions, such as Botrychium lunaria, B. virginianum, and Ophioglossum nudicaule. Most species have narrow ranges, e.g. B. subbifoliatum, endemic to Hawaii, B. lunarioides, southeastern United States, B. oneidense, northeastern North America, B. echo, southwestern United States. The true ranges were obscured by the crude taxonomies of a third of a century ago. Botrychium boreale became much delimited geographically when it was found that the Pacific Northwest plant so-named belongs to another species, B. pinnatum. We used to believe that B. ternatum occurred both in Asia and in North America, but we now know that the American plant a distinct species, B. rugulosum, a narrow endemic, known only in the Great Lakes region from Montreal to Minnesota (Wagner & Wagner, 1982). It not true that members of the Ophioglossales lack diversity. St. John mentions Helminthostachys and Cheiroglossa as distinctive genera, but what about such distinctive elements within genera as Ophioglossum bergianum or 0. pen-