Source: Campaign Setting, pg(s). 216
Flayleaf is a wiry shrub with reddish-brown leaves that grows in almost any temperate environment. Leaves are harvested and dried, and when smoked produce a powerful sedative and hallucinogenic effect similar to drunkenness.  Harvesting the leaves of this drug are dangerous due to the Flayleaf spiders that live on the plants.
Flayleaf as a Drug
It is also a powerful analgesic and muscle relaxant, rendering the user immune to most pain for up to four hours. It also causes the user to become very susceptible to suggestion. The berries of the flayleaf plant are sometimes crushed and mixed with dream spider venom and spiderberry tea to produce a potent hallucinogen called Riddleport Tea. Unlike its cousin, the cabble-weed, flayleaf is highly addictive. Cost varies across regions with a full pouch of it going for around 12 gp in the highly permissive city of Riddleport in Varisia.
- Erik Mona et al. (2008). Campaign Setting, p. 216. Paizo Publishing, LLC. ISBN 978-1-60125-112-1
- James Jacobs, F. Wesley Schneider, Amber Scott, & Greg A. Vaughan. (2008). Second Darkness, p. 21. Paizo Publishing, LLC. ISBN 978-1-60125-142-8
- Mike McArtor. (2008). Guide to Korvosa, p. 56. Paizo Publishing, LLC. ISBN 978-1-60125-078-0
- Tim Hitchcock. (2008). St. Caspieran's Salvation. Shadow in the Sky, p. 71. Paizo Publishing, LLC. ISBN 978-1-60125-115-2