The Many Faces of Poison Ivy
Poison ivy (Rhus radicans) is a woody shrub or vine found throughout the United States. Red-tinged leaves grow in groups of three and have smooth, fine-toothed, or lobed margins, and small, yellow-green flowers form cream-colored fruit. The allergen, predominantly 3-n-pentadecylcatechol, is found in the resinous sap material uroshiol, which is produced by the leaves, fruit, stem, and bark. Therefore, although delayed-hypersensitivity dermatitis induced by contact with poison ivy is usually considered a summer problem in the northeastern United States, it can (and does) occur year-round.
These photographs, which were taken in southeastern Massachusetts, show the changing appearance of the plant during its growth cycle. In mid-May, before the leaves fully emerge, the vine and the cream-colored fruit are visible (Panel A). In July, the red tinge and shiny appearance of the leaves have faded (Panel B). In October, the leaves change color (Panels C and D) and are shed.
Photos and
text by Gregory Parkinson, M.D. Falmouth Pediatric Associates Falmouth,
MA 02540
Published in New England Journal of Medicine, 7/4/02
