"What is a weed? A weed is a plant whose virtues have not yet been discovered." – Ralph Waldo Emerson

Almost every winter my family gets poinsettias, not Christmas trees, to deck the house. These plants are the ideal Christmas décor with their green and red leaves. Yes, red leaves. From afar, many people think the red parts are the petals, but actually they are bracts, modified leaves located below the flowering region. The real flowers (aka cyathia) are yellow and found in the center of each leaf bunch.

A poinsettia proudly shows off its bright red and green leaves.

Although we associate poinsettias with winter, they are typically found in deciduous tropical forests in Mexico and Central America. The Aztecs had cultivated them to make dyes and treat fevers. The plant’s association with Christmas originates in 16th century Mexico. According to legend, there was a girl who was too poor to bring a gift for baby Jesus on his birthday. An angel inspired her to gather weeds and place them at the church altar. Soon after, the weeds sprouted bright red leaves and became poinsettias. In reality, wild poinsettias are considered weeds.

The name poinsettia comes from Dr. Joel Poinsett, the first US ambassador to Mexico (he co-founded the National Institute for the Promotion of Science and the Useful Arts, the predecessor of the Smithsonian Institution!). He introduced them to the US in the 1820s, but we can thank Paul Ecke, Jr., for making poinsettias holiday plants. He suggested growing poinsettia cuttings in greenhouses, allowing for the development of colorful varieties of these plants. He also advertised them on TV and in newspapers, even going as far as putting them on Bob Hope’s Christmas specials.

Despite its Christmas connotation, poinsettias should still be grown at normal room temperature, receive about 6 hours of indirect sunlight each, day, and never experience temperatures below 50 degrees. Also, be sure to hide them from your pets! Although the idea that poinsettia leaves are toxic is a myth, the milky latex can cause an allergic reaction, so try to keep your dog from feeling miserable during the holiday festivities!

Ok, so the crimson red is a pretty sight to see on these plants, but wouldn’t it be super cool if these plants glowed in the dark?! Scientists have already started doing this with the tobacco plant! . These plants are genetically modified so that they can glow as a natural part of their life cycle and not depend on any chemicals or external black light sources (like fireflies!). Scientists inserted genes that make special marine bacteria glow into these plants. I actually saw these bacteria in the waters of Woods Hole, MA, and Fajardo, Puerto Rico. When they sense agitation in the waters, they release light! Since these genes make bacteria glow, the scientists thought it'd be cool to make other stuff glow. So they put the genes (for you science-savvy people, the genes encode for luciferase, an enzyme that makes the light-emitting reaction) into the DNA of plant plastids. Plastids are the structures that contain the color-producing molecules. Although the light that the plants emit is rather dim, the researchers are trying to make it brighter!

Location of the glowing bacteria (Woods Hole, MA)

The scientists are associated with BioGlow Tech (http://bioglowtech.com/), a company that wishes to create glowing plants for ornamental plant growers. So don’t be surprised to see a glowing poinsettia replace your artificially lit Christmas tree in the near future!

     Ok, not a glowing poinsettia tree but still a pretty one! Photo credit: Hema Sundaresan

Happy holidays!

(By the way, December 12 is Poinsettia Day!)