Syrian rue, Peganum harmala, is a low tough shrub of dry ground from Anatolia and the eastern Mediterranean across Iran to Central Asia, and its most widespread use has nothing to do with visions.
The seeds are thrown on charcoal and the smoke is passed around people, doorways, vehicles, shops and newborn children as a protection against the evil eye. In Iran it is esfand, in Turkey uzerlik, and the practice is entirely ordinary: it is done at weddings, on returning from a journey, when someone has been complimented too warmly, and when a business opens. Rhymes are said as the seeds pop.
This is one of the most durable pre-Islamic survivals in the region. It has no basis in Islamic doctrine, it has been objected to by clerics on and off for centuries, and it has continued regardless, protected by being domestic and small rather than by being defended. The seeds are sold everywhere they are used.
The plant is also a longstanding dye source, giving the red of Turkish carpets from its seeds, and a folk medicine for a wide range of complaints. Most of its cultural presence across a very large area rests on those two uses and on the smoke, not on ingestion, and accounts that treat it primarily as an entheogen have the proportions backwards.