In Iranian mythology, the belief in the vegetal origin of man is related to the concept of immortality. Despite the great efforts of Ahriman and his followers in destroying the good and Ahuraic forces, with the transformation of kings and warriors into the bodies of plants, their existence is preserved in a repeating cyclical fashion. Adopting the Content Analysis Method, this study investigates and analyzes the metamorphosis of the most important mythical plants, namely Cypress and Hom. The results of the study show that Cypress is associated with the sun and Mihr. There is no mention of this in the Avesta and Pahlavi texts. Nevertheless, according to the Shahnameh and the Ghoshtasbnameh, the Cypress was planted in the ground by Zarathustra as a sacred tree. Additionally, in Persian mystical sonnets, which are influence by the Iraqi school, Cypress is a symbol of beauty and grace that has maintained its ritual sanctity and significance throughout most eras while its mythological associations have continued to live. Nonetheless, it has sometimes undergone a metamorphosis. Hom is also a Mithraic legendary plant whose juice was used as an intoxicating drink during sacrificial ceremonies, which is why a ban has been placed on it in the old Avesta. In the late Avestan and Pahlavi writings, it partially regains its original significance and is even deified. This myth demonstrates a human transformation in the Shahnameh and Pahlavi texts, and in some mystical passages, it has undergone a transformation by transferring its own actions to the water of life and mystical water.