Final answer:
The word that best describes the line endings of the first two lines of the poem is 'enjambed'.
Step-by-step explanation:
The best word to describe the line endings of the first two lines of this poem is enjambed. Enjambment occurs when a line of poetry extends into the next line without punctuation or pause. In the given poem, the lines 'roses are red' and 'while violets are blue' both carry on to the next line without any punctuation, creating a sense of continuity.