Psilocybin, along with psilocin, is a tryptamine and is the primary active ingredient of some psilocybe and panaeolus hallucinogenic mushrooms (not the same active ingredients as Amanita muscaria or Amanita pantherina). Effects of psilocybin are comparable to those of a shorter LSD trip, although intensity and duration vary depending on dosage, individual physiology, and set and setting. Psilocybin containing mushrooms are preferred by some groups because the mushrooms can be found within nature and lack the chemical taint of LSD and other such manufactured hallucinogens.