[Denatonium]

Another example, this one deliriant and not psychedelic, is atropine/scopolamine, found in certain nightshades, such as deadly nightshade, mandrake, plants in the Datura genus, and trees in the Brugmansia genus. The chemical weapon QNB, also called BZ is another example of a long-acting deliriant.

As far as classic psychedelics go, I've read mescaline (3,4,5-trimethoxyphenethylamine) lasts really long.

[cthalupa]

My experiences with mescaline are that it has mostly wound down by 6-8 hours though I can tell that I am slightly "off" for a few hours after that. Shorter timeframe than LSD, though not by a whole lot.

[davkan]

Young me was always interested in trying datura despite the harrowing trip reports on erowid. Glad i never was presented with the opportunity.

[Denatonium]

I tried it during the summer between 8th and 9th grade after discovering a Datura Stramonium plant growing at a beach on Cape Cod. Fortunately the plant was growing in sand, and the alkaloid content of the plant was very low. I boiled an entire pod down in a soda can and gave it a try. In terms of effects, I did not become delirious, but my perception of gravity was greatly enhanced; I felt like I weighed 600lb. My eyes were also completely incapable of focusing on anything close-up for several days. I never tried Datura again, and I never will. I was lucky I didn't wind up dead, in jail, or in the hospital.