Correspondence

Poison Ivy

N Engl J Med 2002; 347:1723-1724November 21, 2002

Article

To the Editor:

In his contribution regarding poison ivy in the Images in Clinical Medicine section (July 4 issue),1 Dr. Parkinson correctly points out that contact dermatitis from the plant can occur at any time of the year. However, in the interest of total accuracy, the allergenic oleoresin is “urushiol,” not “uroshiol” as printed.

Donald S. Schuster, M.D.
4414 Regent St., Madison, WI 53705

1 References

1. 1

   Parkinson G. The many faces of poison ivy. N Engl J Med 2002;347:35-35
   Full Text | Web of Science | Medline

To the Editor:

We would like to call attention to the commonly perpetuated inaccuracy, which comes down to us from Linnaeus himself, in referring to poison ivy as “Rhus radicans.” Nearly 50 years have passed since poison ivy and its immediate relatives were shown to represent a distinct developmental lineage from the genus rhus, albeit still within the family Anacardiaceae. It is a daunting task to keep abreast of changes in botanical nomenclature; however, the time has arrived for physicians to recognize this botanical advancement and to use the preferred generic name, toxicodendron.

Compelling evidence emerged in the 1950s and 1960s supporting the separation of rhus, with mostly benign plants, from poison ivy and related allergenic plants. In 1971, Gillis convincingly called for placing these allergenic species in the genus toxicodendron.1 The name toxicodendron, meaning “poisonous plant,” originated with Tournefort, who preceded Linnaeus. Thus, it by no means represents new terminology. In addition to allergenicity, the evidence supporting division rests on many observable botanical features.2 Therefore, separation is not merely semantic, but vital to proper field recognition and avoidance strategies. Moreover, the traditional means of recognition based solely on leaf morphology is unreliable, since toxicodendron leaflets vary markedly according to both season and geographic area.

Glen H. Crawford, M.D.
University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283
glen.crawford@uphs.upenn.edu

Thomas W. McGovern, M.D.
Indiana University School of Medicine, Fort Wayne, IN 46805

2 References

1. 1

   Gillis WT. The systematics and ecology of poison ivy and the poison oaks (Toxicodendron, Anacardiaceae). Lawrence, Kans.: Rhodora, 1971.
   

2. 2

   Guin JD, Gillis WT, Beaman JH. Recognizing the Toxicodendrons (poison ivy, poison oak, and poison sumac). J Am Acad Dermatol 1981;4:99-114
   CrossRef | Web of Science | Medline

Author/Editor Response

Dr. Parkinson replies:

To the Editor: I appreciate the updates on nomenclature. To paraphrase Juliet, “A rhus by any other name would itch as much.”

Gregory Parkinson, M.D.
Falmouth Pediatric Associates, Falmouth, MA 02540