St. Vincent and Grenadines Association of Toronto

Poinsettia, Christmas Star

Gallery Image1

Foreground: Poinsettia, Christmas Star
                       Euphorbia pulcherrima Willd. Ex Klotzsch

Background: Allamanda cathartica L.

[Photo by J.A. (Tony) Hadley
Visit http://www.photo.net/photos/thadley to view Tony's portfolio of Images]

The poinsettia (Euphorbia pulcherrima) easily ranks as the most popular Christmas plant, and one of the most lucrative potted flowering plants today. Early accounts indicate that the Aztecs, who used it to make a purple-red dye, and a potion for reducing fever, had cultivated the plant. However, its first use as a symbol of Christmas is attributed to a group of Franciscan priests living in Mexico during the 17th century. Mexicans called the plant Flor de la Noche Buena (Flower of the Holy Night). It is also called the Christmas Star. Supposedly these names arose because the red bracts were thought to resemble the Star of Bethlehem. In the mid-1820's Joel Poinsett, the United States Ambassador to Mexico, sent specimens of the plant to his home in South Carolina, where they were propagated and shared with a few of his friends. The plant was later given the name Poinsettia in his honour.

The botanical genus Euphorbia, to which the poinsettia belongs, is one of about 250 genera in the spurge family (Euphorbiaceae). Plants in this genus often contain a milky sap, which can stain clothing and other such materials, and which in some plants could be toxic if ingested.

For many years, the toxicity of the poinsettia has been a controversial issue. However, experiments in recent years showed no ill effects on laboratory animals, and humans have been known to ingest the leaves with no adverse reaction. Nevertheless, caution is advised when handling the plant, since it appears that some humans suffer skin irritations when in contact with the milky sap. On the other hand, Dr. B.C. Wolverton, a former NASA researcher, gives the poinsettia good marks for its use as an effective tool in removing harmful chemical vapours from indoor air.

The specific epithet pulcherrima, means very beautiful, and this relates to the bright red bracts typical of most poinsettias. These bracts are not really true flowers, but modified, terminal leaves. The true leaves are rich green in colour. The true flowers form a tiny, golden-yellow cluster at the centre of each group of bracts.

In St. Vincent and the Grenadines as well as in other tropical countries the plant grows naturally as a woody, sparsely branching shrub up to 10 ft. or more in height. Worldwide, when grown indoors the poinsettia is used as a potted seasonal plant.

Flowering of the poinsettia is triggered by day length (short days, long nights). Thus, the plant's natural flowering period in the northern hemisphere is such as to bring it into full bloom in late fall or early winter, around Christmas. Potted plants for indoor use are subjected to at least 14 hours of uninterrupted darkness each night, starting in early fall. This induces flower development and colouring of the bracts.

There is an impressive array of cultivated varieties available nowadays, with conceivably many more to come. With bracts of colours such as red, white and yellow, the poinsettia maintains its freshest appearance as a short-term flowering houseplant. But it also has potential as a perennial indoor pot plant, as it can be held over until flowering is finished, then pruned and brought into flower again by manipulating the day length.

Fred Prescod
Horticultural Educator

 

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