Glück often draws upon mythological and religious references in her poems, all the while keeping them relatable or at least accessible to modern readers. This is done through her use of allegory and allusion, speakers who take on the voices of mythological or spiritual figures, and straightforward language carefully arranged for rhythm and repetition. The language used by a poem is particularly important to its capacity to draw the reader in and create a cohesive ethos.
In The Wild Iris, the language can be classified as informal holy language. Holy language is any language that is cultivated and used primarily for spiritual reasons. All of the poems told from the perspective of the gardener-poet are titled "Matins" or "Vespers," which refer to morning and evening prayers. This makes it clear that these poems are a form of communing with the divine. At the same time, the language used in The Wild Iris is rarely presented in an elevated way. One of the only examples of language that is different from everyday speech in the collection is in the poem "Ipomoea," which reads, "my flesh giveth / form to his glory." Apart from that, the speakers in The Wild Iris use informal language. It is partly for this reason that the flower speakers are able to provide insights on the human experience by talking about themselves. For example, Witchgrass speaks about the way it is blamed for the death of flowers, and subsequently targeted by humans for removal. This touches upon the issue of scapegoating, which has occurred throughout human history to devastating effects.
The poems simultaneously employ informal language and a strong sense of spiritual and visionary poetics. American literary critic Helen Vendler has said that "Glück’s language revived the possibilities of high assertion, assertion as from the Delphic tripod. The words of the assertions, though, were often humble, plain, usual; it was their hierarchic and unearthly tone that distinguished them." Though the language in the poems of The Wild Iris is straightforward, it seeks to touch something different in the reader than ordinary conversation would. For example, in "Matins" (#6), the gardener-poet asks the deity, "What is my heart to you / that you must break it over and over...?" And the omniscient deity speaks with both anger and tenderness, such as in the poem "Sunset." All of this functions to provoke deep thought about human relationships to the natural and divine worlds.
