Illinois Natural History Survey - University of Illinois

INHS Reports Summer 2001

The Naturalist's Apprentice: Poison Ivy Look-alikes

by
Carolyn Nixon, Center for Economic Entomology

Now that you know the story of poison ivy, you know that you should avoid touching the plant with three leaflets; however, there are several other plants that also have three leaflets, and some with simple leaves that come in sets of three. Some are easily confused with poison ivy, while others look quite different. Here are just a few. Match the pictures below with the names and descriptions that follow the drawings.

alikes.jpg

1. Trilium is a woodland wildflower and a member of the lily family. It has three glossy, untoothed leaves. The flowers have three petals, and come in white or reddish purple. The white flowers turn pink with age.

 

2. Jack-in-the-pulpit has one or two smooth-edged leaves, each with three leaflets. The flower is a greenish tube with a hood, and has an erect club under the hood.

 

3. Fragrant sumac is a close relative of poison ivy. It has three fuzzy leaflets, with the center leaflet having a short stalk. It has clusters of small, round, fuzzy, red fruit. It grows as a low, spreading shrub about three feet tall.

 

4. Box elder is a type of maple tree that lives in moist woodlands. The leaves have three to seven toothed leaflets, and the seedling box elders usually have only three leaflets.

 

5. Wild strawberry is a low-growing herbaceous member of the rose family. The leaves have three hairy and toothed leaflets. The flowers are white, followed by red fruit.

 

6. Wood sorrel is a common weed in lawns and gardens. Its leaves are three heart-shaped leaflets about 1/2 inch across. It has small yellow flowers each with five petals.

 

7. White clover is a small herbaceous plant that is common in lawns. It has leaves with three finely toothed leaflets and a cluster of tiny white flowers that form a ball about 3/4 inch across.

 

8. Columbine is an upright wildflower with nodding red and yellow flowers. Its light green leaves each have three deeply scalloped leaflets.

 

9. Black raspberry is a shrub with long unbranched stems, or canes, that have many hooked thorns. The younger canes are often covered with a whitesh film. The leaves have three toothed leaflets that are whitish underneath.

 

10. Rough cinquefoil is a spreading or erect herbaceous member of the rose family. Its deeply toothed leaflets tend to fold upward at the edges. It has inconspicuous yellow flowers.




A note for teachers:

There are a few terms that may need to be explained to the students.

 

* A herbaceous plant is one that is not woody.

* Each leaf of a plant will have a bud at its base where it joins to the stem. If the leaf is made up of one section or blade, it is called a simple leaf. If there is more than one section, each of which looks like a leaf but does not have the bud at the base, then it is a compound leaf. Each section of the compound leaf is called a leaflet.

* If the edge of the leaf has pointed projections, it is said to be toothed. If the edge of the leaf has rounded projections, it is said to be scalloped.

* A seedling is a young plant that has recently emerged from a seed.

 

Answers to Poison Ivy Look-alikes: 1-d, 2-e, 3-g, 4-c, 5-j, 6-a, 7-h, 8-f, 9-i, 10-b

 

 


Drawing credits

Poison ivy--Carie Nixon
Wood sorrel--Dover*
Jack-in-the-pulpit--Dover*
Fragrant sumac--Fieldbook of Native Illinois Shrubs, Illinois Natural History Survey Manual 3, Leo R. Tehon.
Box elder--Dover*
Wild strawberry--Dover*
Trillium--Dover*
White clover--Dover*
Columbine--Dover*
Black raspberry--Fieldbook of Native Illinois Shrubs, INHS Manual 3, Leo R. Tehon
Rough cinquefoil--Weeds of the North Central States, North Central Regional Research Publication No. 281, Bulletin 772. University of Illinois at Urbana-Champaign, College of Agriculture, Agriculture Experiment Station.

 

* Dover = Plants and Flowers: 1,761 Illustrations for Artists and Designers. Edited by Alan E. Bessette and William K. Chapman.

 

Charlie Warwick, editor



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