Calea zacatechichi, also known as Dream Herb, Leaf of God, 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.) The plant naturally occurs from southern Mexico to northern Costa Rica. There are currently two reported varieties, one being extremely bitter and the other non-bitter. 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 correct Latin name is Calea ternifolia Kunth, with Calea zacatechichi Schltdl. being a synonym (Wussow et al. 1985). The name zacatechichi retains usage as a local or common name.

The Chontal medicine men, who assert that this plant is capable of "clarifying the senses" causing euphoria, 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, the common ritual is to smoke a cigarette, while drinking a tea, both made of Calea Zacatechichi, right before going to sleep.