rhizophyllum), and verified that A. stotleri was simply a form of A. bradleyi. Allozyme analysis in the 1980s also supported these hybrid origins of A. bradleyi. A chloroplast phylogeny has suggested that A. montanum is the maternal ancestor of A. bradleyi. The species was segregated from Asplenium as Chamaefilix bradleyi by Farwell in 1931. The change was not widely accepted and current authorities do not recognize this segregate genus. Progenitor and hybrids The sterile diploid hybrid of A. montanum and A. platyneuron, which resembles A. bradleyi except for its abortive spores and smaller sori, was not collected until 1972, at Crowder's Mountain, Georgia. Even though the diploid hybrid is rarely collected, allozyme studies show that A. bradleyi has multiple origins; that is, different populations of A. bradleyi have originated from the chromosome doubling of independently formed diploids. Despite their independent origins, these populations are probably interfertile and not reproductively isolated from one another. In addition to its parental species, A. bradleyi hybridizes with several other spleenworts. Its hybrid with A. pinnatifidum was recognized as such by William R. Maxon in 1918. He named it A. gravesii for its discoverer, Edward W. Graves. It can also backcross with its parental species. Wherry collected specimens of A. bradleyi × montanum from a cliff near Blairstown, New Jersey in 1935. It is not thought to have been collected again until 1961, when it was described and named in Wherry's honor. Specimens believed to be A. bradleyi × platyneuron were collected at an early date at McCall's Ferry, along the Susquehanna River. The site of collection was submerged by the building of the Holtwood Dam. A preliminary report of both diploid A. bradleyi and A. bradleyi × platyneuron from Sequatchie County, Tennessee was made in 1989. Distribution One of the "Appalachian spleenworts", A. bradleyi can be found along the Appalachian Mountains from northern New Jersey and Pennsylvania southwest to Georgia and Alabama, and occasionally along the Ohio Valley to the Ozarks and Ouachitas, where it is found in Missouri, Arkansas, and eastern Oklahoma. Populations in Maryland and New York are considered historical. Populations are generally scattered in the Appalachians, but more frequent in the Ozarks and Ouachitas. Ecology and conservation Asplenium bradleyi can be found on steep, acidic rocks from altitudes of . Sandstone is a common substrate, but it can also be found on schist, gneiss, granite, or other acidic rocks. Like A.