Is there any rhyme or alliteration in the poem "Mother to Son"?
Yes, there is some alliteration in this poem. For example, there is alliteration in "Bare / But all the time," and later in the poem, we find "boy, don't you turn back," with further alliteration on the letter b. However, alliteration is not one of the primary characteristics of this poem.
Because of this, we might question why the alliteration should be on the letter b. I would suggest that b is a very bold and strong sound, which is aligned with the tone of the poem. The poem is all about striving, perseverance, and being bold, which is reflected in the sounds of "boy," "back," "been."
In terms of rhyme, if there is any rhyme in the poem, then it is subject to interpretation. Arguably, "stair" rhymes with "bare" several lines later, but this is likely not a deliberate placement of two rhyming words in adjacent lines. The poem itself does not have a rhyme scheme.
Instead of rhyme, it is repetition which gives the poem a sense of unity and cohesion. Hughes starts multiple lines with the word "and," which has a cumulative effect, underscoring the fact that the striving of the mother to ascend the difficult staircase has been ongoing and continuous. The struggles heap upon previous struggles. However, despite this, the mother continues. She moves boldly onwards and she asks her son to do the same, promising that if she can do it, he also can.