Asplenium rhizophyllum one collection on sandstone in the Shawnee Hills of Illinois. A triploid hybrid between walking fern and Tutwiler's spleenwort was accidentally produced in culture. A similar plant collected from limestone in Shepherdstown, West Virginia could have originated from the same parents, from an unreduced (diploid) gametophyte of Scott's spleenwort crossed with walking fern, or from an unreduced walking fern gametophyte crossed with ebony spleenwort. In 1813, Henry Muhlenberg listed lobed spleenwort as "Asplenium rhizophyllum" var. "pinnatifidum", although he did not provide a description distinguishing the variety from the typical species. It was described as the species "A. pinnatifidum" by Thomas
What Is Life love song – perhaps a "lovingly crafted paen" to Harrison's wife Pattie, as Alan Clayson puts it – or a devotional song like many of Harrison's compositions. Ian Inglis writes that the song title suggests a "philosophical debate about the meaning of life", yet its rendering as ""what is my life"" in the choruses "reshapes [the meaning] completely". Theologian Dale Allison finds no religious content in "What Is Life" but notes the "failure of words to express feelings" implied in the opening line (""What I feel, I can't say""), a recurring theme of Harrison's spiritual songs such as "That Is