Well, son, I'll tell you:
Life for me ain't been no crystal stair.
It's had tacks in it,
And splinters,
And boards torn up,
And places with no carpet on the floor—
Bare.
But all the time
I'se been a-climbin' on,
And reachin' landin's,
The short catalog here creates  imagery  that completely contrasts the perfect “crystal stair.” The  polysyndeton  of the word “and” suggests times when she thought her life couldn’t get any worse AND… it did. The rhythm of the short lines also feels like a climb—one hard step after another. 
 The em-dash followed by the word “Bare” slows down the pace of the poem and emphasizes the hard life the speaker’s mother has lived. It’s almost as if the poem has reached a landing, a short repose before continuing the climb.
Mother to Son