How to ID Poison Ivy, Oak, and Sumac

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How to ID poison ivy, oak and sumac (Garden Talk)

 
 
 
 
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Poison Ivy, top left; Poison Oak, top right; Poison Sumac, bottom
Poison Ivy, top left; Poison Oak, top right; Poison Sumac, bottom (Alabama Extension; James H. Miller and Ted Bodner, Southern Weed Science Society, Bugwood.org)

By Bethany A. O'Rear

Q: This summer, I have been feverishly crossing things off of my garden "to do" list. However, this pace has ground to a screeching halt, as I have reached #7 on the list - clean up natural area.  Before I tackle this job, I want to be sure that I know just which plants are poisonous.  Can you help?

A: Funny you should ask this question now, as I am currently recovering from a nasty fight with poison ivy.  Guess who won?  Poison ivy - 1, gardener - 0!  The following information should make identifying these plants a little easier.

As you start cleaning up your natural area, you most likely will encounter one or more of the most common poisonous plants in Alabama - poison ivy, poison oak and poison sumac.

It can be a challenge to distinguish whether you have poison ivy or poison oak.  Each has leaves with three leaflets that join together at a red center. These two species are responsible for the old adage "Leaves of three, let them be." 

The leaflets are commonly 2 to 8 inches long and 3/4 to 5 inches wide and have scattered, jagged teeth along the edges.  One visual difference relates to the shape of the leaflet edges. The edges of the teeth on the leaflets of poison oak are rounded, and those of poison ivy are pointed.

Another difference is the growth habit of each plant. Poison ivy grows as a vine that may run along the ground or up the sides of trees, houses, or other vertical surfaces. The vines, which can vary in size from less than 1/4 inch to more than two inches in diameter, appear "hairy" due to tiny roots that extend from the vine. In contrast, poison oak is shrub like in appearance and has stems up to 3 feet tall.

Poison ivy is found in a wide variety of habitats and is especially common in wooded areas and along forest edges.  Poison oak is typically found in drier, more open forests, fields, and right-of-ways.

Poison sumac is a close relative of poison ivy and poison oak, but it looks very different.  The leaves of poison sumac have 7 to 15 leaflets that are commonly 2 to 4 inches long and 3/4 to 2 inches wide. 

The leaflets, which are arranged along the stem in pairs, are oblong with sharply pointed tips and smooth edges.  The stems and leaf stalks are often a bright red color.  Poison sumac grows as a shrub or small tree, reaching up to 20 feet tall in open or wooded swampy areas.   

Touching any of the three poisonous species may result in an itchy rash of blisters.  One out of every two people is allergic to toxicodendrol, an oily compound found in all parts of these plants. Simply touching the leaves may expose you to the oil, and additional oil is released when plant parts are crushed or damaged. 

 

The oil resists breakdown and may cling to clothing, tools, and pet fur for long periods of time and may even persist on a secondary surface for up to a year.  Touching these secondary surfaces can also cause an allergic reaction. Although not everyone is allergic to these plants, allergies may develop with increased contact; therefore, even people who do not seem allergic now should avoid these plants.

In your case, it sounds like avoidance may not be an option. There is an extremely high probability that you will encounter poison ivy as you clean up your natural area. However, following the tips listed below will be extremely helpful in limiting your exposure.

  • Always wear long pants and close toed shoes when in wooded areas or fields.
  • Do not eat any part of these plants.
  • Carefully inspect tree trunks before touching them since poison ivy often clings to them.
  • Do not burn any part of these plants.  The allergen can become airborne and be inhaled.
  • Always wash clothes immediately upon return from outdoor recreation.
  • Consider hiking in late fall or winter when these plants have dropped their leaves.
  • Be wary of leafy, green plants that carpet the forest floor.  Poison ivy and poison oak commonly grow in this fashion.
  • Wear vinyl gloves with long sleeves tucked in when weeding gardens.
  • Wash skin with cold water and soap or rubbing alcohol within 10 minutes if contact is suspected.  Do not use hot water as this may make the problem worse by opening skin pores.
  • Apply a preventative lotion (several brands available) before going outdoors.

Good luck and happy gardening!

Garden Talk is written by Bethany A. O'Rear of the Alabama Cooperative Extension System (ACES). She is housed at the C. Beaty Hanna Horticultural and Environmental Center, which is based at the Birmingham Botanical Gardens. This column includes research based information from land-grant universities around the country, including Alabama A&M and Auburn Universities. Email questions to Bethany at Bethany@aces.edu or call 205-879-6964 x15. Like us on Facebook. Follow us on Twitter. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University), is an equal opportunity educator and employer.  Everyone is welcome!

 

Source: http://www.al.com/living/index.ssf/2017/06/touch-me-nots_garden_talk.html#incart_river_index