The poinsettia seems as much a part of our culture as baseball or apple pie. But this beautiful plant is actually a native of Mexico, imported in the early nineteenth century because of its colorful leaves. These leaves, often referred to as bracts, function in attracting pollinating insects to the tiny flowers that they surround.
The plant’s namesake is Joel Roberts Poinsett, a botanist, physician, and statesman who as the first U.S. Minister to Mexico brought the plant to the U.S. in 1825. Albert Ecke, a German immigrant, began selling them in California. His son Paul discovered a method of grafting to make them fuller. Then Paul Jr. further developed the propagation techniques and began promoting the plant for use at Christmastime. The Eckes had a monopoly on poinsettias until a university researcher discovered and published the grafting technique. Poinsettia cultivation is a huge business today.
Poinsettias are members of the large and varied spurge family, many of whose members are cactus-like succulents. All have milky sap – the rubber tree is in this family – and most have tiny flowers. The much-reduced male and female flowers are grouped in cuplike cyanthia, which in poinsettias are usually yellow. This diagram (below) of a cyanthium shows three male flowers and one female flower that has been fertilized and is producing a fruit.
To develop flowers, and with them the colorful bracts, poinsettias require long dark autumn nights followed by sunny days, a phenomenon called photoperiodism. It’s difficult – but not impossible – to duplicate the conditions necessary for this color change. Even a small amount of light at the wrong time can result in disappointment.
But there’s nothing disappointing about the gorgeous plants that are everywhere these days. And the bracts aren’t just red anymore. Cultivars out there sport bracts of many shapes and colors. As one newspaper reporter suggested, “No flower says it’s Christmas quite like poinsettias.”