Asplenium platyneuron plant. Similar buds have also been reported from the single-sorus spleenwort, "Asplenium monanthes". The species most similar to "Asplenium platyneuron" is the black-stemmed spleenwort, "A. resiliens". However, this stipe of this species is darker, and the pinnae are opposite, rather than alternate, along the rachis. Neither black-stemmed spleenwort nor the other pinnate American spleenworts have dimorphic fertile and sterile fronds. It might be confused with a young Christmas fern, "Polystichum acrostichoides", but that species is generally much larger and has a green, scaly stipe and rachis. It is very similar to Boydston's spleenwort, "Asplenium × boydstoniae", a backcross with Tutwiler's
What Is and What Should Never Be and What Should Never Be" was performed live at Led Zeppelin concerts between 1969 and 1973. A live version taken from a performance at the Royal Albert Hall in 1970 can be seen on the "Led Zeppelin DVD". Another was included on disc two of the live triple album "How The West Was Won". Two more versions were included in BBC Sessions. What Is and What Should Never Be "What Is and What Should Never Be" is a song by English rock band Led Zeppelin. It was written by Jimmy Page and Robert Plant and was included as the second