What forms and devices are used in the poem?

This poem is an exercise in multiplicity. The poet invokes multiple literary devices and multiple forms within "Blackberry Eating."
Forms. This poem is a clever hybrid between a sonnet and a free verse poem. This poem does not have a rhyme scheme or a regular meter. In this sense, it is a free verse poem. However, the poem is structured in fourteen lines, which invokes the form of a traditional English sonnet. The irregularities of the rhyme and meter speak to the freedom of the speaker's spirit. Echoing the form of a sonnet, which is a classic form for a love poem, conveys the speaker's amorous, passionate feelings as " the ripest berries / fall almost unbidden to my tongue." Combining the two forms, one informal and one formal, also portrays the comingling of unlike sensations; the berries are both "prickly" and "fat," "icy" and "overripe."
Devices. Kinnell chooses his words carefully to make the use of repetition an effective poetic device. The words "blackberry," "ripe," "icy," and "squinched" all appear multiple times in the poem. These are words with challenging consonant sounds or otherwise hard vowel sounds. They are difficult to form yet rewarding to say, not unlike the blackberries themselves. Each challenging word is like eating one such berry, as emphasized by the poet's repetitive use of them. The poem also features similes to shed light directly on the point, the central theme of the poem. Eleven out of fourteen lines describe the action of picking or eating blackberries. Those three lines which do not are made up of two similes which read: "as words sometimes do, certain peculiar words / like strengths and squinched, / many-lettered, on-syllabled lumps." The poet uses these similes to take a step back from the obvious subject of the poem (blackberries) and reveal the deeper subject of the poem: the act of writing itself.