Carnivorous plant often waterlogged, which favours the production of toxic ions such as ammonium, and its pH is an acidic 4 to 5. Ammonium can be used as a source of nitrogen by plants, but its high toxicity means that concentrations high enough to fertilise are also high enough to cause damage. However, the habitat is warm, sunny, constantly moist, and the plant experiences relatively little competition from low growing "Sphagnum" moss. Still, carnivores are also found in very atypical habitats. "Drosophyllum lusitanicum" is found around desert edges and "Pinguicula valisneriifolia" on limestone (calcium-rich) cliffs. In all the studied cases, carnivory allows
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