First: they’re not poison. My grandmother, like generations of grandmothers, feared that I as a toddler, my kids as toddlers, puppies, kittens—any innocent given to gnawing things—would eat poinsettia petals and die. 

Robert McMahon of the Ohio State University Agricultural Technical Institute in Wooster:

Nor are poinsettias, like mistletoe or lighted trees, old Christmas traditions from Europe.

"And, those rich red petals aren’t…petals: they’re leaves called bracts. The tiny, yellow, berry-looking things at the CENTER of the bracts are the petals."