POISONOUS PLANTS

The most common plants hikers and bikers come across are Poison Ivy, Poison Oak and Poison Sumac. The sap from these plants can cause a rash, burning, and itching if touched. A skin rash may develop within a few hours or it may be within two days. It usually takes about two weeks for the rash to run its course. In some cases a doctor should be consulted.
An infection can occur from scratching the rash. There is nothing to make the rash go away, but Calamine lotion may help you feel better. It's important to stay very clean. Shower and carefully towel dry.

It is important to wash all clothing and even shoe strings. The plant oil, urushiol, can stay active for a long period of time. 

Poison Ivy

Poison Ivy (Toxicodendron radicans) has shiny green leaves that grow in groups of three. Poison ivy may grow as a vine or as a low shrub. Two leaflets grown on opposing sides and the third stands by itself at the end of the stalk. The edges of the leaflets may be smooth, lobed or toothed.

Deer and other animals happily eat poison ivy. Don't be fooled into thinking the plant is safe just because you can see other animals consuming it.

Poison Oak

Poison Oak (Toxicodendron rydbergii) also has leaves grouped in three. It grows as a low shrub and may have clusters of green or white berries.

Poison oak is widespread throughout the mountains and valleys of California. It thrives in shady canyons and the banks of rivers or lakes. It commonly grows as a climbing vine with aerial roots that adhere to the trunks of oaks and sycamores.

Poison Sumac

Poison Sumac (Toxicodendron vernix) has 7-14 leaves found in pairs with a single leave at the end. These long, smooth leaves are bright orange and velvet-like in the spring. They become dark green and glossy on top and light green underneath. Poison Sumac can grow as a tree in swampy areas.

Poison Sumac is less common than Poison Ivy and Poison Oak and found only in extremely wet areas of Eastern United States.

Rhymes to Remember

  • "Hairy vine, no friend of mine."
  • "Longer middle stem; stay away from them." -- the middle leaflet has a long stem while the two side leaflets attach almost directly.
  • "Raggy rope, don't be a dope!" Poison ivy vines on trees have a furry, "raggy" appearance.
  • "Berries white, run in fright" and "Berries white, danger in sight."


  • "Red leaflets in the spring, it's a dangerous thing." -- new leaflets sometimesare red in the spring. Later, in the summer, the leaflets are green -- while in autumn they can be reddish-orange.
  • "Side leaflets like mittens, will itch like the dickens." This refers to the shape of some poison ivy leaves, where each of the two side leaflets has a notch that makes the leaflet look like a mitten with a "thumb." (Caution: all parts of the plant can cause itching, not just these leaves.)
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