Toxicodendron diversilobum. Western poison oak in flower. The scalloped leaflets have no sharp points, but this is not always the case. Flower clusters hang down. Only female plants will continue on to produce fruit. Male flowers are used for pollination only. (photo: Sandra J. Baker)

Photos of poison oak–poison ivy—poison sumac

Toxicodendron diversiloba. Western poison oak easily climbs a redwood tree. Allergenic resin leaking from a bark wound soon hardens and turns pitch black. With sun exposure, it might turn a chalky grey over time.
(photo: Sandra J. Baker)

In this poison oak picture (Toxicodendron diversiloum), these two mature leaves of western poison oak are from one plant.(Remember, one botanical leaf consists of 3 leaflets). I am not allergic any more, but I always scrub my hands with dry dirt (clay) after touching the plant just in case. If you are allergic, don't touch the plants on purpose. (Photo by Sandra J. Baker)

Toxicodendron radicans. This beautiful eastern poison ivy vine is obviously loved and pruned as it hugs a garden shed. (photo by Judy Feller)

Toxicodendron vernix. Looking like a sumac, poison sumac is actually closely related to poison oak and poison ivy. It has the same allergenic oil, urushiol. Some folks insist the allergen in poison sumac is stronger than the other two, but there apparently have been no clinical studies on the subject of which is the stronger of the three, except for a casual test by a researcher who rubbed the bruised leaves on volunteers. No differences were seen. (Photo: Ted Bodner.Plants Database/James H. Miller and Karl V. Miller. 2005. Forest Plants of the Southeast and Their Wildlife Uses)

Toxicodendren radicans. Eastern poison ivy. The leaflets of eastern poison ivy have sharper tips than those of most western and eastern poison oak plants. This is a young vine with few aerial roots. (the roots that hold the plant to the post or tree). With no climbing support like the tree, this plant would grow as a shrub. (photo: John Paine)

This is a good example of how various plants can become jumbled together, and you may be unaware that poison ivy is right in front of you. Did you notice poison ivy leaf (consisting of three leaflets) near the bottom left corner?.
Look for the three leaflets. The middle one, hanging down toward the corner has a longer leaflet stem than the side leaflets. This is one of the identifying clues. (
photo: permission by www.poisonivy.aesir.com

This mature eastern poison ivy vine has more aerial roots than the younger vine on the left. Old poison ivy trunks are sometimes so covered with aerial roots, they resemble old frayed roots.
(photo: Judy Feller)

In the spring and summer this bush looks alive. When the western poison oak leaves turn red in the fall, we realize it is using the dead bush as a support system.
The color of the leaves can be bright or just a dull yellow or tan. Amounts of sun and water can affect fall leaf color.
(photo: Sandra J. Baker)

The fruit of poison oak, ivy and poison sumac (called drupes) are small and about the size of a pea. When young, the skin is smooth with a green tint. When the fruit matures, the outer skin falls off. As you can see above, the fruit resembles tiny peeled oranges. (photo: Sandra J. Baker)

Toxicodendron rydbgerii.Western poison ivy. Once considered a subspecies of eastern poison ivy, T. rydbergii now has a spot as a separate speies, although some botanists disagree.
This plant is a shrub, not a vine and the leaflets fold up like butterfly wings. (
photo: Daniel Boelman)

As spring progresses, the bronze color changes to green in the new leaves. (photo: Sandra J. Baker)

The leafless branch hanging over the path is actually a western poison oak plant in wintertime.
This is very typical for these plants, because they are always leaning toward the sunnier areas in paths or country roads.
An unsuspecting hiker is likely to bump into this branch, but the experienced hiker will notice the distinctive growth pattern.
(photo: Sandra J. Baker)

This western poison oak leaflet (they are not all lobed) shows the distinctive veining that poison oak and poison ivy have.
See the mid vein? the smaller veins going off to the side are alternating, instead of being directly across from each other.
(photo: Sandra J. Baker)

2 USDA Sumac

I only have a couple of pictures of poison sumac. Since it lives in swampy areas, folks are not as likely to come accross it. The leaflets of poison sumac are said to resemble rabbit ears in shape. What looks like a stem with 9 leaves on it is actually one leaf. The midrib is always red, as seen in the photo to the right.

The branch in the foreground is a great example of how a western poison oak or eastern poison ivy branch, without any support, will reach toward the sun. The upward curve at the end of the branch is a dead giveway.
Also notice how simple the growth is—one branch, short side shoots. No masses of offshoots going here and there.
(photo: Sandra J. Baker)

This powerful allergenic oil in the resin of poison oak/ivy and poison sumac is almost identical to that in the Japanese lacquer tree, Toxicodendron vernicifluum. The famous lacquerware of Japan, China and Korea is created with this oil that flows out of the trees in the resin. It creates one of the strongest membranes known when painted on objects. Its only failing is that the sun degrades it.
There is a slight difference in the allergenic oil of poison oak/ivy that keeps it from having the strength of the asian plants. (
photo: Sandra J. Baker

Toxicodendron diversilobum. Western poison oak has sparse aerial roots when compared to those of eastern poison ivy. It grows way up into the crowns of huge trees by nestling into cracks in the bark here and there. (photo: Sandra J. Baker)

Western poison oak grows up a ponderosa pine by creeping under pieces of bark.
Note the golden resin on the left. Poison oak/ivy/sumac resin turns pitch black upon exposure to air.
(photo: Sandra J. Baker)

This eastern poison ivy is growing among cactus. It is impossible to remove without digging everything up. The roots are rhizomes that grow laterally just under the soil. Leave a little bit, and it keeps growing. (photo: John Paine)

These red growths are galls, Gall mites have laid eggs in the plant tissue.
(photo: Sandra J. Baker)

these pictures will help you identify the allergenic plants,
but follow the idendification system in the book, and know for sure


The first chapter of this fun book has thirteen pages dedicated to identifying the plants. Just follow the author's easy-to-use system.

Click on the home page (brown button at top of this page) to find out more about the book.

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