PHENOLOGY: The flowering requirements of dumbcane are not often met when it is grown as a houseplant.
DISTRIBUTION: Native to tropical America, Dieffenbachia is now a favorite plant for greenhouses and interior decorations for homes and businesses.
PLANT CHARACTERISTICS: Stems: stout, green, girdled with leaf scars, unbranched, bearing leaves toward the top; leaves: entire; petioles: sheathing; leaves and petioles often spotted or variegated; flowers: unisexual; plants sometimes having a skunk-like odor when bruised. The inflorescences arise from the leaf axils on stalks shorter than the leaf petioles. The inflorescence consists of an erect spike (the spadix), which has female flowers at the bottom and male flowers at the top; the two groups of flowers are separated by a short section of naked spadix. A petal-like sheath (the spathe) enfolds the lower pistillate flowers and provides a background foil for the staminate flowers.
POISONOUS PARTS: All parts contain toxic principles, but the stems are especially poisonous. Oral administration of the toxic component (juice from plants) to guinea pigs showed an LD50 between 600 and 900 mg of stem/animal in 24 hr. Injection i.p. produced an LD50 of 1 g. A single-dose oral toxicity test in rats showed an LD50 over 160 ml/kg of the whole plant juice.
SYMPTOMS: Ingestion of dumbcane causes rapid irritation of the mucous membranes, burning, copious salivation due to release of kinins, edematous swelling and thickening of the tongue and lips, local necrosis, and difficulty in swallowing and breathing. The symptoms may last for several days to longer than a week.
POISONOUS PRINCIPLES: Mechanical and chemical actions of calcium oxalate may be partly responsible for the reaction to dumbcane. A protein (proteolytic enzyme named "dumbcain") fraction also is possibly responsible, as well as the compound asparagine.
CONFUSED TAXA: Some common cultivated house plants such as Aglacnema (Chinese evergreen) and Spathiphyllum (peace lilies) could be confused with dumbcanes. Aglacnema differs from Dieffenbachia in having inequilateral leaf bases and the spadix not united with the spathe. In Spathiphyllum the leaves are in clusters, not originating on a stout stem as in the above two genera. Two species of Dieffenbachia are commonly cultivated: D. Sequine Schott and D. maculata (Lodd,) G, Don. Hybridization and natural mutation have created many fancy-leaved forms that are exploited commercially and should be considered poisonous.
SPECIES OF ANIMALS AFFECTED: Humans and house pets are susceptible.
TREATMENT: (11a) (b); (4); (6); (9); (10); (26); (2 - i.v. diazepam); analgesics for pain (meperidine); intravenous fluids to maintain adequate hydration.
OF INTEREST: Other aroids commonly cultivated as house plants should be considered potentially toxic, including Alocasia and Colocasia (dasheen, elephant ears), Caladium (angelwings). Anthurium (tailflower), Monstera (Swiss-cheese plant, ceriman), and Philodendron (see Philodendron). In one case cattle developed severe irritation of mouth and tongue after grazing on Colocasia. Cases of severe poisoning from Alocasia, Caladium, and Xanthosoma (Blue taro, Indian Kale) have not been recorded in the U.S.