I propagated my Christmas cactus from a very large specimen donated to my university's horticulture department along with several colors of Thanksgiving cacti and some hoyas by a woman who could no longer care for them due to deteriorating health. My heart goes out to people like these who must give up what they love because their minds or bodies are no longer able to care for them.
|My Christmas, I mean Valentine's Day, cactus must have known February would bring some miserable weather. It's kept me in happy suspense through January and is now bursting with color just when I need it most.|
In what is turning into typical fashion, being the annoying know-it-all that I am, I'd like to share a few distinguishing characteristics about the Christmas cactus. Many people are not aware that what is typically sold in stores around the Christmas holiday is not the true "Christmas" cactus. They are almost always cultivars or hybrids of Schlumbergera truncata, which is traditionally known as the Thanksgiving cactus. Of course, Schlumbergera x buckleyi is itself a hybrid between S. x russeliana and S. truncata, so what difference is there, really?
The cultivars and hybrids of Schlumbergera truncata classified as "Thanksgiving" cacti have points on their stem segments, or phylloclades, and tend to be more upright or spreading. The true Christmas cactus, Schlumbergera x buckleyi, has scalloped edges on rather pendulous stems.
When in flower, Christmas and Thanksgiving cacti are easily differentiated by their blooms. The flowers of Christmas cacti point straight out from the end of the stem (which usually hangs down) and are radially symmetric (actinomorphic), like a daisy. Thanksgiving cacti are a little kinkier, having a distinct bend in the ovary that causes the flower to point out horizontally. The petals also flair up and back, making the flower zygomorphic (meaning a line can be drawn down it to make two mirror halves).
Ironically, the least reliable distinction between the two groups is also the one that lead to their common names. Thanksgiving cacti are supposed to bloom around Thanksgiving, while Christmas cacti typically bloom around Christmas, right? Did you catch those key words, "supposed to" and "typically?" Really this just means that Thanksgiving cacti bloom a few weeks earlier than Christmas cacti, but the actual bloom time is dependent on temperature and day length. Bloom time can be manipulated by controlling day length and temperature to produce flowers almost any time of year. Thanksgiving cacti require a shorter period of cool temperatures and/or short days/long nights to initiate bloom, thus they have become the favored holiday cactus in the trade. In the home, these plants need to be kept in a place where they will not receive artificial light in Fall as the days get shorter, like a spare bedroom you don't need to get into frequently after dark in the fall. If the plants are exposed to light after the sun goes down (or after your grow-lights are turned off for the night), most of the developing flower buds will abort and fall off. You'll still get a few flowers, but not mass flush of blooms that you see in stores. Cool temperatures in the 50-60 degree Fahrenheit range also helps, but is not critical.
Of course, further hybridization of Schlumbergera has resulted in more intermediary types between Thanksgiving and Christmas cacti, blurring the distinctions in stem shape, bloom shape, and bloom time, but at least this gives you a better guess as to what you are actually buying (or the ID of that plant that's been passed down from Grandma, a traditional method of receiving holiday cacti). Luckily, newer cultivars are also easier to rebloom than older selections, being less dependent on that careful control of light I discussed above.
The following two pictures are of Thanksgiving cacti. Note that the flowers are held horizontally, with the petals on the bottom reflexed to lie flat along the rest of the flower and the rest of the petals pointing straight up. You can also see the points on the stem segments, typically four per segment.
|The blooms of Thanksgiving cacti always remind me of some sort of exotic bird with wings thrown back and up.|
|Take a look at the bud above the open flower. This shows particularly well the bend at the base of a Thanksgiving cactus flower.|
The following pictures are of Christmas cacti. Technically it's all the same plant, as the last three pictures are of my plant, which was grown from cuttings taken from the plant in the first picture. What I really wish these photos captured is the complex blend of colors in the flowers. They have an almost iridescent quality in sunlight. They start out pink touched with some fantastic shade of red (carmine, vermilion, I don't know), and as they age a purple sheen develops, like oil on water. You can actually see a little of the red shades in some of these photos, but the purple oil slick is indiscernible from the base pink color. It seems to blend in, making the pink a little more purplish than it really is.
|The blooms on my plant, grown in a house, have less red and almost none of that illusive, possibly hallucinatory purple sheen, but aren't they lovely just the same?|
|This flower, still opening, shows the red shades a little better, I think.|
My Favorite Plant This Week is hosted by Loree, of Danger Garden fame. You can see her favorite this week by clicking here
Until next time...