Community News, Ideas, & Comments
Natural Environment · 19th November 2010
Sherry Wellborn
Poison oak (Toxicodendron diversilobum is a native plant that used to be on my eradicate list. I have been forced to re-evaluate my perspective.
"Leaves of three, leave them be" still applies for me. I can manage very minimal contact with this plant, but, like many people, develop a painful, long-lasting rash from the urushiol oil that is present in its leaves and bark.
Poison oak is lovely, with shiny three-lobed leaves that turn brilliant scarlet in fall. It's bark is tan and it grows as a shrub in full sun or as a vine in partial shade. It's Latin name describes both its toxicity and its diversely shaped leaf. It loves our hot, scrubby, southwesterly exposed slopes.
I'm teaching a landscape plant identification class at LCC, and one of my students chose this plant to present to class. Her presentation was an education for me. If you'd like to see Maria's powerpoint presentation, click on the web link at the end of the article.
This plant is highly nutritious for grazing animals. In particular, the foliage can contain significant amounts of calcium, phosphorus, and sulfur. If the foliage has those minerals, that means its roots are pulling them up out of the soil. As the leaves are deposited on the soil surface, the minerals are released. That makes these plants important mineral cyclers. Isn't it amazing that deer, sheep, horses, and goats can eat the stuff without harm?
The flowers are great sources of nectar for bees making honey. Poison oak honey? Wow. Don't worry, the urushiol stays behind. The fruits are white. We can't eat them, but they're important for birds who do.
Human sensitivity to poison oak varies. The smoke is toxic and should never be inhaled. However, reports of Native American use of this plant exist. It was used to destroy warts, and some tribes used it for weaving baskets; although a close relative was used more often. Native Americans may have less sensitivity as a population than Europeans as a group. The lacquer used by the Japanese is made from a close relative of poison oak. Contact with that can cause irritation in some people.
Anyway, I don't plan on making any bouquets with poison oak, but I appreciate it much more. It is beautiful, and plays several important functions in the environment. I may remove it from my pathways in the future, but leave it and appreciate it in the background.
Photos from OSU Landscape Plant Website: http://oregonstate.edu/dept/ldplants/
"Leaves of three, leave them be" still applies for me. I can manage very minimal contact with this plant, but, like many people, develop a painful, long-lasting rash from the urushiol oil that is present in its leaves and bark.
Poison oak is lovely, with shiny three-lobed leaves that turn brilliant scarlet in fall. It's bark is tan and it grows as a shrub in full sun or as a vine in partial shade. It's Latin name describes both its toxicity and its diversely shaped leaf. It loves our hot, scrubby, southwesterly exposed slopes.
I'm teaching a landscape plant identification class at LCC, and one of my students chose this plant to present to class. Her presentation was an education for me. If you'd like to see Maria's powerpoint presentation, click on the web link at the end of the article.
This plant is highly nutritious for grazing animals. In particular, the foliage can contain significant amounts of calcium, phosphorus, and sulfur. If the foliage has those minerals, that means its roots are pulling them up out of the soil. As the leaves are deposited on the soil surface, the minerals are released. That makes these plants important mineral cyclers. Isn't it amazing that deer, sheep, horses, and goats can eat the stuff without harm?
The flowers are great sources of nectar for bees making honey. Poison oak honey? Wow. Don't worry, the urushiol stays behind. The fruits are white. We can't eat them, but they're important for birds who do.
Human sensitivity to poison oak varies. The smoke is toxic and should never be inhaled. However, reports of Native American use of this plant exist. It was used to destroy warts, and some tribes used it for weaving baskets; although a close relative was used more often. Native Americans may have less sensitivity as a population than Europeans as a group. The lacquer used by the Japanese is made from a close relative of poison oak. Contact with that can cause irritation in some people.
Anyway, I don't plan on making any bouquets with poison oak, but I appreciate it much more. It is beautiful, and plays several important functions in the environment. I may remove it from my pathways in the future, but leave it and appreciate it in the background.
Photos from OSU Landscape Plant Website: http://oregonstate.edu/dept/ldplants/
Leaves emerging in early spring.
Plant habit in fall.
White fruit of poison oak (poisonous).
Fall leaves.
Poison Oak
Comment by Anne Donahue on 22nd November 2010
Nice article and information. Now I too have a better appreciation for this plant.
I’ll never forget as a freshman in college how I shimmied up an oak tree to grab a cluster of mistletoe to tack over the doors of all the freshman girls in my dorm. I didn’t know that the foliage covering that tree was poison oak. I broke out in the worst rash in those “shimmy” places and had a very difficult time passing my finals. And all that mistletoe, well, I think there were quite a few kisses being passed around under those doorways, but I didn’t get a single one.
Nice article and information. Now I too have a better appreciation for this plant.
I’ll never forget as a freshman in college how I shimmied up an oak tree to grab a cluster of mistletoe to tack over the doors of all the freshman girls in my dorm. I didn’t know that the foliage covering that tree was poison oak. I broke out in the worst rash in those “shimmy” places and had a very difficult time passing my finals. And all that mistletoe, well, I think there were quite a few kisses being passed around under those doorways, but I didn’t get a single one.