What can you use for X on a alliteration poem?

poetry, language sung, chanted, spoken, or written according to some pattern of recurrence that emphasizes the relationships between words on the basis of sound as well as sense: this pattern is...

it beautifies the poem

The repetition of the same consonant sound at the beginning of two or more words in close succession. Example: Peter Piper picked a peck of pickled peppers.

It means is a 5 lined poem that has to rhyme.

same beginning consonant sounds.