All articles starting with P
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Psiloceras
Psiloceras is a smooth-shelled psiloceratid ammonite genus of the earliest Jurassic (Hettangian). Psiloceras planorbis traditionally marks the Jurassic base; Psiloceras spelae tirolicum defines the ratified GSSP at Kuhjoch, Austria, about 201.3 Ma.
Psilocin
Psilocin (4-hydroxy-N,N-dimethyltryptamine) is the active metabolite of psilocybin, isolated from Psilocybe mexicana by Hofmann in 1958; a 5-HT2A agonist causing psychedelic effects.
Psilocybe
Psilocybe (liberty caps, magic mushrooms) is a genus of psilocybin-producing agaric fungi, type species Psilocybe semilanceata, split from the non-psychoactive genus Deconica in 2007, with about 165 species and a psilocybin gene cluster that spread by horizontal transfer.
Psilocybe azurescens
Psilocybe azurescens (Stamets & Gartz, 1995) is a highly potent, bluing psilocybin mushroom native to Oregon and Washington, growing on wood chips and coastal sandy soils, with reported alkaloid content up to 17.8 mg/g.
Psilocybe cubensis
Psilocybe cubensis (basionym Stropharia cubensis Earle, 1906, Cuba) is the world's most cultivated psilocybin mushroom, a coprophilous subtropical fungus with an 11–22 kb Psi gene cluster and African sister species P. ochraceocentrata.
Psilocybe cyanescens
Psilocybe cyanescens (wavy caps), a bluing psilocybin mushroom described by Wakefield in 1946, wood-chip mulch dweller of the Pacific Northwest and Europe; psilocybin 3.0–15.6 μg/mg dry weight.
Psilocybe hispanica
Psilocybe hispanica is a hallucinogenic Psilocybe mushroom described by Guzmán in 2000 from the Aragonese Pyrenees, Spain, growing on horse dung in alpine meadows, and identified in a 6,000-year-old Spanish mural.
Psilocybe ochraceocentrata
Psilocybe ochraceocentrata, a 2026-described psychoactive African mushroom in Agrocybaceae, sister species to Psilocybe cubensis, found on cattle dung in South Africa, Zimbabwe, and Zambia grasslands.
Psilocybe semilanceata
Psilocybe semilanceata, the liberty cap (Agaricus semilanceatus Fr. 1818), is a small psilocybin-containing grassland mushroom of Europe and North America; caps 5–25 mm, psilocybin 0.33–15.77 μg/mg dry weight, poisonous with symptoms 20–60 minutes after intake.
Psilocybin
Psilocybin, also known as psilocin phosphate ester, is a naturally occurring psychedelic compound produced by certain mushrooms that the body converts to psilocin, an investigational treatment for depression.
Psilocybin and psilocin
Psilocybin and psilocin are tryptamine alkaloids responsible for the psychedelic effects of magic mushrooms. Psilocybin is a prodrug converted in the body into psilocin, the active molecule acting on serotonin receptors.
Psilocybin decriminalization in the United States
Psilocybin decriminalization in the United States: state and local reduction of criminal penalties for psilocybin, starting with Denver 2019, Oregon Measure 109 in 2020, and Colorado Proposition 122 in 2022, while psilocybin remains federally Schedule I.
Psilocybin mushroom
Psilocybin mushroom (magic mushroom, shroom), a Psilocybe or related fungus containing psilocybin and psilocin, serotonin 5-HT2A agonists causing 6-8 hour hallucinogenic effects; studied for depression and addiction, Schedule I in the US.
Psilocybin-assisted psychotherapy
Psilocybin-assisted psychotherapy, also known as psilocybin therapy, is a treatment in which supervised psilocybin dosing sessions are embedded in structured psychological support, studied mainly for treatment-resistant depression.
Psiloritis (Timios Stavros)
Timios Stavros (Holy Cross), summit of Mount Psiloritis (Ida) in central Crete, Greece; at 2,456 m the island's highest and Greece's most prominent peak, in Psiloritis UNESCO Global Geopark.
Psiloritis UNESCO Global Geopark
Psiloritis UNESCO Global Geopark (Γεωπάρκο Ψηλορείτη) is a Greek geopark in central Crete, designated 2015, covering 127,200 ha around Mount Psiloritis (2,456 m) with Permian-to-present rocks, karst caves, and mitata shepherd shelters.
Psilotum
Psilotum, the whisk ferns, a genus of two rootless, leafless vascular plants (P. nudum, P. complanatum) in Psilotaceae, native to tropics and subtropics, now placed within the ferns near Ophioglossaceae.
Psilotum complanatum
Psilotum complanatum (flatfork fern, moa nahele), a flattened-stemmed whisk fern of Psilotaceae from tropical America, Asia, and the Pacific; now treated as the hybrid Psilotum x complanatum between P. nudum and P. flaccidum.
Psilotum nudum
Psilotum nudum (whisk fern, moa in Hawaii) is a rootless, leafless eusporangiate fern of Psilotaceae with forked aerial shoots and three-fused sporangia (synangia), pantropical in distribution, once called a living fossil but now placed near Ophioglossaceae within true ferns.
Psion
Psion was a British handheld-computing company founded in 1980 by David Potter, known for the Organiser and Series 3 and 5 palmtops running its EPOC system.
Psionics
Psionics is a term for the study of psi powers, such as ESP and telepathy, coined by Jack Williamson to label psychic abilities within fiction.
PSIP1
PSIP1 (LEDGF/p75, DFS70) is a human chromosome 9p22.3 gene encoding chromatin-tethering coactivators p75 and p52, the HIV-1 integrase cofactor, and a protein implicated in leukemia and cancer.
Psiphon
Psiphon is a Canadian open-source censorship-circumvention tool operated by Psiphon Inc. of Toronto, relaying Internet traffic through proxy servers using VPN, SSH, and obfuscated transports.
PsiQuantum
PsiQuantum is a quantum computing company founded in 2016 by four UK academics that builds photonic quantum computers and aims for fault-tolerant machines of about one million qubits.
Psithyrus
Psithyrus (cuckoo bumblebees) is a subgenus of Bombus of about 28 obligate social parasite species that lack pollen baskets and workers, invade host bumble bee nests, kill or cohabit with the queen, and use chemical mimicry or repellents.
Psittacidae
Psittacidae (parrots) is a family of Psittaciformes birds established by Illiger in 1811, with nearly 350 species, about 28% threatened; classification scope varies from two-family to three-superfamily schemes.
Psittacosis
Psittacosis (parrot fever, ornithosis) is a zoonotic pneumonia caused by Chlamydia psittaci from birds; incubation 5–14 days, doxycycline treatment, under 1% mortality when treated, rare human-to-human spread.
Psittacula
Psittacula (Cuvier, 1800) is a genus of long-tailed Asian parakeets including the rose-ringed and Alexandrine parakeets; molecular phylogenies show it is paraphyletic, prompting proposed splits into Himalayapsitta, Alexandrinus, Palaeornis, and related genera.
Psittaculidae
Psittaculidae, the Old World parrots, is a parrot family in Psittaciformes with about 175–190 species, split from Psittacidae after molecular phylogenies; sister to cockatoos and New Zealand parrots.
Psittacus
Psittacus is a genus of African parrots established by Linnaeus in 1758, containing the gray parrot and the Timneh parrot of the West and Central African rainforests.