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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Interesting Facts about Holiday Plants

This article was published originally on 12/9/2009

The poinsettia, Christmas cactus, and mistletoe can be found in many homes during the Christmas and New Year's holidays. The poinsettia and Christmas cactus are prized for their colorful flowers. Mistletoe is hung in the home for those wishing to kiss under the mistletoe. While the poinsettia, Christmas cactus, and mistletoe are recognized by nearly everyone, many individuals aren't aware of interesting facts about the plants.
Poinsettia
The poinsettia is native to Mexico. Poinsettias were cultivated by the Aztecs. The colorful bracts were used to make a reddish purple dye. The poinsettia's milky sap was used to treat fevers.  Poinsettias were first introduced into the United States by Joel Roberts Poinsett, the United States Minister (ambassador) to Mexico from 1825 to 1829. Poinsett had plants sent to his home in South Carolina. He then distributed plants to horticultural friends and botanical gardens. The Ecke family of California has been instrumental in the development of today's poinsettia. 
 
The colorful part of the poinsettia, commonly referred to as the plant's flowers, are actually modified leaves or bracts. The true flowers are yellow to green, button-like objects located in the center of the bracts. 
 
Poinsettias are short-day plants. Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in the fall. In order for poinsettias to flower for Christmas, they must receive complete darkness from 5 p.m. to 8 a.m. each day from early October until the bracts show good color, usually around early December. (Most poinsettia varieties require 8 to 10 weeks of short days to flower.) 
 
Contrary to popular belief, the poinsettia is not poisonous. However, it is not intended for human or animal consumption. Individuals are still advised to keep the poinsettia out of the reach of small children and pets. 
 
One potential health problem associated with the poinsettia is dermatitis or an irritation to the skin. When a poinsettia stem is cut or broken, milky sap oozes from the wound. Some individuals may develop a skin irritation if the milky sap comes in contact with their skin. 
 
Christmas Cactus
 
Holiday cactus is a more accurate name as a plant purchased during the holidays may be a Christmas cactus (Schlumbergera bridgesii), a Thanksgiving cactus (Schlumbergera truncata), or a hybrid. Christmas and Thanksgiving cacti are similar in appearance. However, the stem segments on the Christmas cactus have scalloped edges, while the stem segments on the Thanksgiving cactus have 2 to 4 pointed teeth along their edges. 
 
Schlumbergera bridgesii and Schlumbergera truncata are native to the mountainous forests of southeastern Brazil. Holiday cacti are epiphytes. They grow in the crotches of trees and derive water and nutrition from rains, decaying organic matter, and filtered sunlight. 
 
The stems of holiday cacti are composed of flattened stem segments or phylloclades. The leaf-like phylloclades carry on photosynthesis for the plant. 
 
Day-length and temperature control the flowering of both Schlumbergera species. Like the poinsettia, holiday cacti are short-day plants. Plants will not bloom properly if exposed to artificial light at night. Flowers may also fail to develop if the plant is exposed to temperatures above 70 degrees F. Night temperatures of 60 to 65 degrees F with slightly warmer daytime temperatures are ideal for flower formation. 
 
Mistletoe
Mistletoe is a semi-parasitic plant with small, leathery leaves and small, white berries. Mistletoe plants manufacture their own food, but must obtain water and minerals from the host plant. 
 
American mistletoe (Phoradendron serotinum) can be found growing in deciduous trees from New Jersey and southern Indiana southward to Florida and Texas. It is the state flower of Oklahoma. Mistletoe sold during the holiday season is gathered in the wild. Most mistletoe is harvested in Oklahoma and Texas. 
 
Mistletoe fruit are poisonous. For safety reasons, most companies have replaced the fruit with artificial, plastic berries. 
 
The scientific name Phoradendron is derived from Greek and literally means "thief of the tree." 
 
As you gaze upon the poinsettia, Christmas cactus, and mistletoe this holiday season, enjoy the beauty and traditions of these holiday plants. However, don't forget some of the interesting facts about these unique plants