While the ending of Rosemarys Baby reveals the heroine has been drugged with Tannis Root, viewers might be surprised to learn the truth about this herb. Rosemarys Baby is a classic feminist horror movie wherein the newlywed Rosemary moves into an exclusive apartment building and becomes pregnant, only to find herself surrounded by creepy occurrences and ghoulish coincidences. As bodies begin to pile up and Rosemary grows increasingly paranoid, the isolated homemaker becomes convinced that she is at the center of some strange conspiracy. Infamously, the truth turns out to be something even darker than that.

https://screenrant.com/rosemarys-baby-tannis-root-ingredient-substance-explained/