PHENOLOGY: Like Dieffenbachia and other aroids, philodendrons are cultivated primarily for their lush green growth; they seldom flower in cultivation.
DISTRIBUTION: Philodendron, a very common house plant grown for its foliage, is native to the warm regions of the Americas, including the West Indies. The genus has 200 species.
PLANT CHARACTERISTICS: Philodendrons vary considerably in appearance. Identification of the many species is complicated by differences in form and size of leaves between juvenile and adult growth stages, and by the vast number of hybrids that have been produced commercially. Young plants of many species have similar leaves and often are impossible to identify. Most philodendrons have climbing stems with aerial roots, although some may be erect and freestanding; plants: evergreen, perennial; leaves: alternate, large, thick and shining. entire to variously lobed or pinnatifid. The philodendron variations are too numerous to list in this brief treatment.
POISONOUS PARTS: All parts of the philodendron plant are toxic. Leaves and stems are dangerous when eaten in quantity.
SYMPTOMS: In addition to those symptoms described for Arisaema and Dieffenbachia, philodendron can cause mouth, tongue, and lip irritation. One researcher has reported 72 cases of "philodendrum" (sic) poisoning in cats, with more than half resulting in deaths. Symptoms included debilitation, listlessness, and kidney malfunction, although these were not associated with apparent pain.
POISONOUS PRINCIPLES: Aroid toxins, including calcium oxalate needles and perhaps proteins or amino acids, are responsible for toxicosis.
CONFUSED TAXA: The philodendrons can be informally grouped into four categories: trailing with slender, weak stems; stouter-stemmed vines with entire leaves; stouter-stemmed vines with lobed ("cut-leaf") leaves; and shrubby, nonvining ("giant"). Of the trailing type, P. scandens C. Koch & H Sello and P. cordatum (Vello) Kunth are commonly grown. Within the stouter-stemmed vine (entire leaves) category, P. domesticum Bunt is popular. Those stout vines with divided leaves include P. radiatum Schott and hybrids like P. x "Florida". Shrubby philodendrons generally are not encountered in homes in Pennsylvania; however, they are planted in tropical gardens, grown under glass in conservatories in the temperate region, and used in interior displays at shopping malls.
Other genera sometimes confused with vining philodendron are Pothos and Scindapsus; some "split-leaf" philodendron are actually Monstera and Epipremnum. Because the genera listed above also are in the Araceae, they should be considered potentially dangerous.
SPECIES OF ANIMALS AFFECTED: Humans and house pets, especially cats, are susceptible to arum toxins.
TREATMENTS: Aroids, including Arisaema, Dieffenbachia, and Philodendron, can be treated similarly. General treatment includes: (6); (2 - diazepan i.v.); (11a) (b) except in severe swelling; milk, water, or antacids to dilute the calcium oxalate and to flush out and soothe the oral pharynx; analgesics (e,g. meperidine); (4 - effectiveness is equivocal); and maintenance of hydration (intravenous fluids).