Perhaps the first religious connotations were placed on poinsettias during the seventeenth century. Because of its brilliant color and holiday blooming time Franciscan priests, near Taxco, began to use the flower in the Fiesta of Santa Pesebre, a nativity procession.
After supplying his own greenhouses, Poinsett also distributed plants to various botanical gardens and to some horticultural friends, including John Bartram of Philadelphia. Bartram, in turn, supplied the plant to Robert Buist, a nurseryman, who first sold the plant as Euphorbia poinsettia. The botanical name had already been given by a German taxonomist in 1833 as Euphorbia pulcherima. The poinsettia, however, has remained the accepted name in English speaking countries.
The widespread belief that poinsettias are poisonous is misleading. Ohio State University, in cooperation with the Society of American Florists, have conducted numerous studies to determine the "toxicity" of poinsettias. Their findings - a 50 pound child would have to ingest over 500 poinsettia bracts to surpass the amount tested in the study and even at this high level, no toxicity was demonstrated. But remember, poinsettias are not intended for human or animal consumption AND some folks can develop a rash from handling the sticky sap.
Look for plants with fully mature, thoroughly colored and expanded bracts (the colorful parts of the poinsettia). Avoid plants with too much green around the bract edges. Dark, green foliage is another sign of good plant health.
Be sure the plant has good shape and proportion. Generally speaking, the plant should be approximately 2-1/2 times taller than the diameter of the container. Look for plants with stiff stems, lots of bracts and no signs of wilting, breaking, or drooping.
MOST IMPORTANTLY - check out the tiny yellow flowers in the center of each cluster of bracts. If it's a nice tight bud or just showing a little yellow, that typically means the the poinsettia is at its peak of freshness. If the flowers are wide open or "gone" pass and look for another.
There are always lots of parties and celebrations during the holiday season. Don't overlook the opportunity to offer your host a beautiful poinsettia as a way of saying thanks for their hospitality.