Some material on dieffenbachias sent to me by the Florida Foliage Association in Apopka, has led to some startling discoveries. The report named the dieffenbachia as one of the 10 most popular indoor foliage plants, but failed to identify the rest of the group. Curious to learn the identity of the other nine, I called the Market News Service of the Florida Department of Agriculture, the agency that makes the computations.
According to the department's latest figures, issued a month or two ago, dieffenbachia holds the No. 3 spot on the list, behind pothos and ivy, respectively. The remaining seven champions, in order of standing, are spathiphyllum (peace lily), philodendron, dracaena (some varieties called corn plant or dragon tree), palms, schefflea (umbrella tree), aglaonema (Chinese evergreen) and syngonium (usually referred to as arrowhead vine).
Dieffenbachia is popularly known as dumb cane. The name derives from a substance in the plant that renders mute anyone foolish enough to chew on its parts.
According to Lyn Goodrich, a registered nurse and certified poison information specialist at the Maryland Poison Center of the University of Maryland's School of Pharmacology, dieffenbachia contains oxalic crystals, which release a poisonous juice when crushed. The acid can produce severe pain and swelling of the mouth, tongue, gums and voice box. The effect of the swelling can be loss of speech for 24 to 48 hours. However, as long as the airways remain open, a victim will not be in mortal danger. It's unlikely, Ms. Goodrich adds, that enough sap would be ingested to be absorbed into the bloodstream.
With no antidote as yet developed, the best remedy, Ms. Goodrich says, is to rinse the mouth out frequently and drink cold liquids. A child experiencing intense pain should find relief in sucking on a Popsicle, which has a numbing effect.
In the case of pets -- cats in particular have a propensity for nibbling on houseplants -- chomping on dieffenbachia brings on vomiting and difficulty in walking, in addition to the more common swelling of the mouth and even kidney failure and death.
Besides sharing the affection of the public, more than half of the PTC rest of the indoor foliage plants on the list of the 10 most popular also contain oxalic crystals, I discovered, and could therefore inflict harm if eaten. They include, according to Ms. Goodrich, pothos, some varieties of ivy (Boston ivy, in particular), spathiphyllum, philodendron, aglaonema and syngonium. Shefflera can cause skin irritations, but not internal injury. Palms and dracaenas alone are non-toxic.
As for the features of dieffenbachia, it's a member of the aroid family. The Florida Foliage Association describes the modern types as "sports," or hybrids created in plant breeding, developed from the original species found in South and Central America. The account also said that, in general, the new dieffenbachias are superior to the old types in more pronounced variation and compact growth and shorter leaf stems. In most cases, too, when lower leaves die and the main stem elongates, branching will occur at the base. For indoor decoration, dieffenbachias offer sizes suited to floor, table-top and dish-garden display.
Worthy cultivars to choose from include Tropic Snow, Bali Hai, Golden Sunset, Camille, Nelly, Triumph and Paradise.
In caring for dieffenbachia, the Florida group recommends temperatures of 70 to 80 degrees Fahrenheit. Temperatures of 55 degrees or lower can chill the plant and may cause it to lose leaves. Dieffenbachia should be watered about once a week. If the plant has overgrown its pot or is large and situated in a bright environment with low humidity and air circulation, a plant will probably need it more often. The soil should be kept relatively moist but not constantly wet. Plants standing in water that has drained into a saucer may suffer root rot.
If the air in a room is dry, running a humidifier eases the stress on dieffenbachia. As for fertilizing, newly purchased dieffenbachias usually have enough nutrients in the soil to last a month or more. From then on, an application of a level teaspoon of a 3-1-2 or a 1-1-1 type of fertilizer in a quart of water is recommended every one to three months. More frequent fertilizing may be needed for plants in bright locations. Water the plant thoroughly with the fertilizer solution during each application.
If a plant outgrows its pot, you can avoid repotting it by taking off the dominant center shoots near the base. That will reduce the plant's height and encourage secondary shoots to develop. The Florida group says that with many of the new self-branching cultivars, periodic removal of one or two of the dominant shoots improves the plant's appearance.