The colorful leaves of poinsettias are called bracts. 

The bracts can  be pH indicators.

To test this, I took a leaf from a stunning red poinsettia, shredded it, placed it in 20 milliliters ( 4 tsp, 1 tbsp) of rubbing alcohol, and heated it for 30 seconds, I separated it into three portions and put a splash of white vinegar in one (for the acid) and baking soda in the other to make it alkaline. I left the third untouched as a control. Here are the results:

It isn’t as stunning as you would see with red cabbage but if you know anyone disappointed that they aren’t getting a chemistry set for the holidays, it’s a cheap thrill. At least for nerds like me.

Poinsettia plants originated in Mexico. They are named after the botanist who introduced them to the United States, Joel Robert Poinsettia. He dug up Mexican “weeds” growing along the side of the road and brought them back to South Carolina in the mid 1800s. Poinsettias are by far the most widely sold potted plant in the United States. The most popular colors are red, white, and pink in that order.

During the holiday season, give your poinsettia plenty of water and sun. Don’t let it sit in water. Move the pot out of the foil and onto a saucer or poke holes in the foil and let it drain into a saucer. They hate drafts and cold windows so protect yours and the blooms will last 6-8 weeks.

After the holidays, you can cut back on the watering and fertilizer and let it go dormant. Water if it gets droopy but no more. Resume fertilizing in late March. Put it outside during the summer and pinch the tips in August to encourage branching.

To get a poinsettia to reflower you have to keep it in total darkness  for at least twelve hours and if you can keep it in the dark between 5 pm and 8 am. It will take a while. “Start this around October 1st and continue until color shows on the bracts; usually around early to mid-December. Any little exposure to light can prevent flowering. Covering the plant with a light-proof bag and placing it in a closet might work.”http://extension.illinois.edu/poinsettia/faq.cfm

They aren’t really poisonous but contain latex-like sap that can cause allergies and be irritating to pets. There’s no reason to avoid them and you can even experiment with them. Enjoy!