Calea zacatechichi, also known as Dream Herb, Cheech, and Bitter Grass, is a plant used by the indigenous Chontal of the Mexican state of Oaxaca for oneiromancy (a form of divination based on dreams.) It has been scientifically demonstrated that extracts of this plant increase reaction times and the frequency and/or recollection of dreams versus placebo and diazepam. It is also employed by the Chontal people as a medicinal herb against gastrointestinal disorders, and is used as an appetizer, cathartic anti-dysentery remedy, and as a fever-reducing agent.
The Chontal medicine men, who assert that this plant is capable of "clarifying the senses", call it thle-pela-kano, meaning "leaf of God". Whenever they desire to know the cause of an illness or the location of a distant or lost person, dry leaves of the plant are smoked, drunk in infusions, and put under the pillow before going to sleep. Reportedly, the answer to the question comes in a dream.
Preparation & Dosage
Crushed dried leaves are steeped in hot water, and the resulting tea is drunk slowly, after which the user lies down in a quiet place and smokes a cigarette of the dried leaves of the same plant. The human dose for divinatory purposes reported by the Chontal people is a handful of the dried plant. The user knows that he or she has taken a large enough dose when a sense of tranquility and drowsiness is experienced and when he or she hears the beats of his or her own heart and pulse. Calea is a rather bitter herb. Many users prefer to smoke it rather than drinking the tea. There are no reports of hangover or other undesirable side effects.2
Growing Calea from seeds is a difficult task, the most common way to grow it is propagation from cuttings. The Calea plant likes full sun, good drained soils and a lot of irrigation. A good soil mix for calea cultivation is: 1/3 of a rich substrate, 1/3 vermiculite and 1/3 of humus.
Propagation from seeds can be tried with the following method: Sow the seeds in a pot with the soil mix indicated as above. Don't cover the seeds, moisten the seeds with water and cover with a plastic bag. This little greenhouse needs from 4 to 6 hours of light to germinate. If the seeds dry out during this period, the plants will not germinate.
Calea zacatechichi is an unscheduled substance in the United States, meaning that it is completely legal to grow and sell. However, Louisiana State Act 159 makes the substance illegal to grow, cultivate, harvest or sell in that state if intended for ingestion. The act applies to more than 40 types of plants. 
Tennessee proposed a bill that would have made many "hallucinogenic" plants, including Calea zacatechichi, illegal when "intended for human consumption," but the law was changed to only ban Salvia divinorum. 
- Psychopharmacologic Analysis of an Alleged Oneirogenic Plant Calea zacatechichi L Mayagoitia, JL Diaz, CM Contreras, Journal of Ethnopharmacology 18 (1986) 229-243 Eleavier Scientific Publishers Ireland Ltd
- Ethnopharmacology and taxonomy of Mexican psychodysleptic plants. Diaz JL. J Psychedelic Drugs. 1979 Jan-Jun;11(1-2):71-101.
- Erowid. "Calea zacatechichi Legal Status Erowid.org. Jun 20 2006.
- Erowid E. "Comments on New State Laws Controlling the Consumption of Hallucinogenic Plants." Erowid.org. Jun 20 2006.
- Calea Zacatechichi resources at Erowid
- Calea Zacatechichi resources at Lycaeum
- Calea Zacatechichi- Dream Herb