Opuntia diploursina Opuntia diploursina Opuntia diploursina is a species in the Cactaceae family, that grows near and in Lake Mead National Recreation Area and northward across Nevada's Mormon Mesa, into Utah. This species is a close relative and probable ancestor of "Opuntia erinacea", but "...differs in minor spines more closely appressed to pad surface, spines smaller in diameter and more flexible, inter-areolar distance less, upright growth habit, larger fruit with longer, more flexible spines, larger seeds, and diploid chromosome number (2n=22)". "Opuntia diploursina" is also related to another diploid species, "O. trichophora", but differs from that species, as stated in the original
What Is and What Should Never Be descending riff [of "What Is and What Should Never Be"] is amazing: It's like a bow is being drawn back, and then it releases. The rhythm of the vocals is almost like a rap. It's insane — one of their most psychedelic songs." This was also one of the first songs recorded by the band for which Robert Plant received writing credit. According to rock journalist Stephen Davis, the author of the Led Zeppelin biography "Hammer of the Gods: The Led Zeppelin Saga", the lyrics for this song reflect a romance Plant had with his wife's younger sister. "What Is