Natural History of Holiday Plants Exhibit
Evergreens | Holiday Color | Poinsettia | Holly | Mistletoe
Christmas Cactus | Christmas Tree | Common Holiday Plants
Scientific name(s): various Schlumbergera (Zygocactus) species or cultivated hybrids, especially Schlumbergera x buckleyi
Plant family: Cactaceae-Cactus family
Other common names: Orchid Cactus
The Christmas Cactus is a succulent perennial which lacks spines and is native to the South American tropics of Brazil. Like many tropical cacti, this holiday favorite is an epiphyte, which means it lives on other plants. Unlike a parasitic plant that obtains nutrients from its host, epiphytes just use their host as substrate, a place to live. The genus (Schlumbergera) to which the Christmas Cactus belongs is one of the most widely cultivated and enjoyed groups of cacti in the world. They have been extensively hybridized by artificial means in order to produce a wide range of different colored flowers, including magenta, white, pink, salmon, and orange. The closely related Thanksgiving Cactus or Crab Cactus (Schlumbergera truncata, syn. Zygocactus trucata) is also common in horticulture and may even be one of the parent species of the hybrid Christmas Cactus. The showy flowers produced by these cacti are pollinated in nature by birds.
Do Christmas Cacti have leaves?
The green, flattened, leaf-like structures that make up the majority of a Christmas Cactus are actually modified stem segments called cladodes. The stems of our local species of prickly-pears or nopals (Opuntia spp.) are also called cladodes since they too are flattened and leaf-like. In most cacti, the leaves have been modified into spines which have many different functions for the plant, or as in the Christmas Cactus, the leaves and spines are absent.
What does day length and darkness have to do with holiday flowers?
Various plant species require cues from the environment to regulate the timing of certain events, like flowering. This mechanism called photoperiodism occurs when plants initiate flowering or other activities in response to relative lengths of daylight and darkness. In winter, the days get shorter and the nights get longer. This is a very important indicator to some plant species, e.g., Christmas Cactus, Poinsettia, and some Chrysanthemum species, to stimulate them to start flowering. In these species it is actually the longer period of darkness, not the brevity of light, that seems to be important in helping them to recognize their appropriate flowering times. Commercial growers have been able to manipulate flowering times by artificially changing light regimes in greenhouse settings in order to induce plants to flower at a particular time of the year, e.g., Poinsettias in bloom during the holidays. Although many of our favorite holiday flowers are "short-day" plants since they require at least 12 hours of uninterrupted darkness to stimulate flowering, it should be noted that some plants are "day-neutral" and are capable of flowering regardless of the amount of light (or darkness) they receive each day. In these species, flowering is controlled by other factors.
Continue to Christmas Tree
Text by Jon P. Rebman, Ph.D., Curator of Botany