Poison Ivy, Oak and Sumac: Identification, understanding, treatment and prevention
by Ric Hubbard • September 27, 2020
The plants that you find in the wild can be a key resource, but they can also represent a threat. Poison Ivy, Poison Oak and Poison Sumac are three plants that are detrimental to people when encountered in the wild. It is important to know these plants and the danger they pose.
Poison Ivy, or Toxicodendron radicans, is a member of the Cashew family that is found as a vine or a shrub. As a shrub, it may stand up to 4ft tall and as a vine it may grow on trees or other support or may be a trailing vine up to 9.8 inches tall. It is most easily recognized by its trifoliolate leaves with each leaf have three leaflets.
The leaves are generally elongated and pointed, but this may not always be the case as you will find rounded leaves on some plants, even on the same plant. It produces yellow-white or green-white flowers between May and June and its fruits mature by August to November. The leaf color ranges from light green when young to dark green as they mature until the Fall, when they turn brown or red. Fully mature leaves take on a shiny appearance.
Two species of Poison Oak exist in the United States. Western Poison Oak, or Toxicodendron diversilobum, and Eastern Poison Oak, or Toxicodendron pubescens. In the same way that Poison Ivy is not a true Ivy, both species of Poison Oak are members of the Sumac family and are not related to true Oaks. It gets its name from the similarity its leaves have in appearance to real Oak leaves.
It grows as a dense shrub in open sunlight that reaches 13 ft tall, a treelike vine that may be up to 100 ft long with a 3 to 8-inch trunk or as dense thickets in shaded areas. The appearance can vary anywhere in between. It has 3 leaflets per leaf, each from 1.4 to 3.9 inches long. On rare occasions, you will find 5, 7 or 9 leaflets.
The leaflets in general resemble the leaves of Oak trees and are typically bronze when first unfolding and turn bright green in spring. In the summer, they turn yellow-green to reddish and bright red or pink in the fall. From March to June they produce white flowers that, if fertilized, develop into greenish-white or tan berries.
Toxicodendron vernix, or Poison Sumac, is a shrub or small tree found in the Eastern United States that can grow to 30 feet in height. The leaf stems are red and have 7-13 leaflets, each 2-4 inches long. They are oval-to-oblong and tapper to a sharp point, are wedge-shaped at the base and have wavy edges.
They produce greenish flowers and mostly spherical fruits about 0.2 inches across. These fruits are creamy white and grow in a cluster. Poison Sumac grows exclusively in wet and clay soils, usually in swamps and peat bogs.
Of the three plants we are discussing, Poison Sumac is the most toxic. According to some botanists, Poison Sumac is the most toxic plant species in the United States.
The organic compound at the root of the danger is called Urushiol. It is an oily organic allergen found in all three of the plants discussed here as well as the Lacquer tree and parts of the Mango tree. Urushiol is a mixture of several closely associated organic compounds. Each consists of a catechol substituted with an alkyl chain with 15 or 17 carbon atoms.
I am not going to delve into the exact scientific explanation, but it does have a bearing on how it affects the individual. A saturated Urushiol is composed of single bond carbons while unsaturated has increasing numbers of double and triple carbon bonds. The more unsaturated the compound, the more people it will affect and the stronger the reaction. Saturated Urushiol will affect less than 50% of the population while the compound with two or more levels of unsaturation will affect 90%.
Once it has penetrated the skin it is recognized by the immune system’s Langerhan’s cells, those that are actively involved in the capture, uptake and processing of antigens. They, in turn, move to the lymph nodes where they present Urushiol to T-Lymphocytes and cause pathology through productions to cytokines and cytotoxic damage to the skin.
The skin of most people reacts to Urushiol with an allergic rash. This presents with redness, swelling, papules, vesicles, blisters and streaking. People vary greatly in their sensitivity. In 15 to 30% of people, Urushiol has no affect and 25% of people have a very strong allergic reaction. Since this is an allergic reaction, it can grow worse with repeated exposure.
The rash takes one to two weeks to run its course and may cause scars, depending on how severe the exposure. While discomfort for the duration of the rash is the most common issue, severe cases that include blisters can lead to secondary infection, usually Staphylococcal or Streptococcal, that must be treated with antibiotics.
Burning the plants can cause a reaction as well. The Urushiol will be carried in the resulting smoke and can affect more of the body than touching the plant.
There is a risk, especially with Poison Sumac, that burning these plants will lead to Pulmonary Edema. If the Urushiol is breathed in with the smoke the resulting reaction can lead to fluid entering the small air sacs in the lungs. This reaction will require proper medical attention as it is life-threatening.
Immediate Action and Treatment
If you act within the first ten minutes of contact, most of the Urushiol can be removed with either alcohol or soap and water. A spray bottle of alcohol carried in your outdoor gear can be used to spray down the area of contact to help in removal. A better choice is a small squirt bottle of dish soap.
Pour the soap on the affected area and then pour water over it. Urushiol is an oil so use a washcloth to scrub the area clean of the oily compound and then rinse in clean water.
If a reaction begins you should use a topical skin protectants such as zinc acetate, zinc oxide or Calamine to reduce the discomfort. Baking soda or colloidal oatmeal can also help with minor itching. Topical corticosteroids, such as Cortisone-10, can provide relief in more severe cases. Benadryl, containing Diphenhydramine, can also offer relief.
Jewelweed is an age-old treatment for the contact dermatitis resulted from these plants. It is often erroneously called the “cure” for Poison Ivy, but what it in fact does is treat the symptoms of contact.
It is also known as impatiens, touch-me-nots, snapweed and patience. They are a family of 850 to 1000 species of flowering plants. They are widely distributed through-out the Northern Hemisphere and the Tropics and they can be either annual or perennial.
The Spotted Touch-Me-Not and Jewelweed flower from July to October. The Spotted Touch-Me-Nots produce a yellow flower and Jewelweed produces an orange-red flower. The flowers are similar in appearance to horn shape with larger petals to the bottom of the flower to attract pollinators such as bees.
They prefer wet, shady ground to grow in. This will often put them in the same kind of areas that Poison Ivy is found in. The plants grow to 3 to 5 feet tall with large oval shaped, toothed leaves that are opposite lower and alternate in the upper parts of the plant. The base of each stem joint is bulbus and maroon in color and has the appearance of being liquid filled, which is is
To use Jewelweed to treat Poison Ivy, Poison Oak and Poison Sumac, as well as insect stings and other maladies that cause itching, you use the mucilaginous inner pith of the plant as a poultice applied directly to the affected area. This liquid has an anti-inflammatory and anti-histamine effect that brings quick relief to most people.
The best way to prevent Urushiol Dermatitis is to identify and avoid contact with these plants. There are also several barrier creams and lotions that can be purchased that slow the penetration of the oil. It is important to remember that they do not prevent penetration, they only slow it. They are applied an hour or less before possible contact and must be re applied every 4 hours. They must also be washed off within 4 hours of contact or Urushiol will penetrate and a rash will appear. Lastly, they have no effect after exposure and cannot be used by children under 6 years of age.
Your time in the outdoors should be fun, not miserable. Knowing how to identify, prevent and treat the effects of Poison Ivy, Poison Oak and Poison Sumac will help to ensure that you come home with good memories and decrease the impact if you come in contact.