Conium maculatum disturbed ground. It is used as a food plant by the larvae of some Lepidoptera species, including silver-ground carpet. The poison hemlock moth ("Agonopterix alstroemeriana") feeds on the plant during its larval stage. "A. alstroemeriana" has been widely used as a biological control agent for "C. maculatum". Poison hemlock flourishes in the spring, when most other forage is gone. All plant parts are poisonous, but once the plant is dried, the poison is greatly reduced, although not gone completely. The plant is poisonous to animals that graze on it. "Conium" contains the piperidine alkaloids coniine, N-methylconiine, conhydrine, pseudoconhydrine and gamma-coniceine
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