I've been looking up different versions of the legend of the poinsettia. The gist of the story is this:

Long ago, a young child in Mexico looked forward to the village's annual Christmas celebration. One year, the child was worried. Other kids were bringing gifts to lay at the manger, and the child was poor with nothing to bring.

On the way to the celebration, the child saw some green weeds along the roadside, and felt an impulse to bring these to the manger. The child lay the weeds there and left.

In the days or minutes that followed, the weeds took root and grew into beautiful bright red plants. The villagers called the wild blooms 'Star of Christmas' and 'Flora de Noche Buena'.