The poinsettias so widely used as Christmas flowers are native to Mexico and came from an area 30 to 60 miles south of Mexico City. Because of their color and holiday blooming time, Franciscan priests used them in their nativity procession, Fiesta de Santa Pesebre. They were introduced to the United States by our first ambassador to Mexico, Joel Robert Poinsett. Being a botanist, he was fascinated by this flaming red flower which he found growing wild ont the hillsides.

The Aztecs who first cultivated it called it Cuetlaxochitl, and later it became known throughout Mexico as Flores de Noche Duena, Flower of the Holy Night. In English it is called poinsettia after Joel Poinsett.

The poinsettia now grows outdoors in areas with mild winters, such as Florida and Southern California. It grows profusely, almost wild, in Hawaii and the Caribbean islands.

Poinsettias are naturally red. However, they mutate to shades of pink, white and marbled. Red is still the most popular color used at Christmas.

Today's highly improved poinsettias are much more satisfying and longer-lasting than they used to be. Breeders have had tremendous success in developing hybrids that can take a lot of punishment and come up smiling. First was J. C. Mikkelsen, of Ashtabula, Ohio, and then Thormod Hegg of Osla, Norway, and Paul Ecke, of Encinitas, Calif.

As good as these new varieties are, they still require personal care in the home. The important considerations are light, water and temperature, according to Ecke.

It is important to give the plant as much light as possible. Full daylight near a window is best. Dim light will shorten the period of its attractiveness.

Some plants need watering every day, others not so often. Use roomtemperature water. Water when the soil is dry to the touch and apply it until it comes out the drainage holes at the bottom. Wait 10 to 15 minutes for excess water to drain and empty the saucer. If the pot stands in water for several hours or longer, the roots of the plant may be damaged.

Ideal temperatures never exceed 72 degrees during the daytime or 65 at night. They really do best at 60 with high humidity. Temperatures above 75 with low humidity are detrimental. Avoid hot or dry air, drafts or sudden changes. The top of the TV is a disaster area because of heat generated by the set.

A poinsettia plant is past its prime when it has lost its green foliage and begins to shed some of the colored flower petals. Iwth all this foliage gone, watering frequency should be reduced.

Many people save their poinsettia and try to make it bloom the following Christmas. Dr. James B. Shanks, University of Maryland professor of horticulture, who has done considerable research on it, suggests keeping the plant alive indoors until minimum outdoor temperatures reach 50 to 55 degrees. Then repot it, cut it back and put it outdoors until mid-September.

The poinsettia actually can be made to bloom at most any time of the year, not just for Christmas. Give it a long night, 13 or 14 hours of uninterrupted darkness for 10 to 12 weeks, and it will bloom for Mother's Day, or any other appropriate holiday.