With summer in full swing, many of us enjoy hiking, picnicking, or simply playing in our many beautiful wilderness parks. There are a few poisonous plants on trails throughout Santa Clarita Valley and neighboring communities, and to keep you safe and free from misery, you should be aware of what they are.

POISON OAK (Toxicodendron diversilobum). Almost everyone knows we have poison oak in California. Pacific poison oak can be found from the coast to our mountains as high as 5,000 feet.

The plant can appear as a bushy shrub or a climbing vine. This plant gets its name because the leaf structure looks similar to that of an oak tree. In the spring, the leaves are light to dark green. In fall, the leaves turn red, yellow, orange, even a deep purple, or a combination of these colors.

The old saying, “Leaves of three – let them be” is good advice. But exposing your skin to the leaves isn’t the only way to get that dreaded itchy, blistery rash.

Some people can develop allergic reactions just by walking past the dry, leafless, reddish-brown sticks of the plant during winter. Those little sticks can be just as dangerous as touching the leaves, flowers, berries or roots.

Poison oak

What causes that nasty rash? The plant releases toxicodendrol, an oily resin that contains a highly toxic chemical called urushiol. This resin cannot be washed away with plain water.

This unpleasant chemical can seep into leather hiking boots, tennis shoes, or whatever you’re wearing. Wear contaminated shoes or clothing again, and you can start all over with your discomfort. A reaction to the chemical can take overnight to appear, or depending on your susceptibility, up to 14 days to rear its ugly head. Secondary exposure can result from contaminated gardening or camping equipment, sports gear, etc.

Personal experience: Hiking in Big Sur down a hill to a beach, through chaparral (get this: in leather sandals. Hey, it was the 1960s.) I never saw any signs of poison oak because it was underneath the chaparral where I couldn’t see it. A few days after returning home, I began having symptoms of numerous huge blisters that itched so badly, I couldn’t stand it. The itching just wouldn’t go away. The reason? I kept wearing those stupid leather sandals that were “soaked” in urushiol. I went to a dermatologist who told me I had a “rare foot condition.” Really?

Exposure is characterized by redness of the skin, blisters, swelling and severe itching that develops in 24 to 48 hours. But this can vary. Some will experience discomfort in 30 minutes, while others can take up to 14 or 15 days to develop symptoms.

Typically, the reaction is most severe around the fifth day after exposure. Mild cases can last from 7 to 10 days. Severe cases can last up to three weeks or longer. It has been noted that people with pale skin are more susceptible than dark-skinned individuals, and younger people are more susceptible than the elderly.

Stinging nettles

What can you do? Milder cases can be treated with any anti-itch medication that contains diphenhydramine. Calamine lotion is a good topical treatment. If the symptoms are severe, see a physician immediately for a stronger medication containing steroids.

Note: There is no poison ivy on the West Coast. That’s strictly an East Coast thing.

STINGING NETTLES (Urtica dioica). The stem and leaves of this plant have zillions of little, silicatipped hairs containing a toxic oil that will enter your skin like tiny hypodermic needles. The hairs will go into your skin and break off, releasing an extremely irritating fluid.

This toxin was originally thought to be the same as formic acid, similar to what ants emit. However, recent research has shown the toxin to be a combination of several different chemical compounds. This sting doesn’t cause a rash like poison oak or sumac, but it surely will make you wish you’d worn long pants when you were hiking.

Stinging nettles

This native plant grows 2 to 4 feet high. It’s often found near streams, manure piles or shaded areas. Believe it or not, this plant is edible, but you’d better look online for curing the plant before you eat it.

There are many products made with nettles in medicinal or vitamin form that can be purchased as an anti-inflammatory. But if you should trot through stinging nettles while hiking off the trail, try apple cider vinegar to sooth the irritants.

POISON SUMAC (Toxicodendron vernix). This plant is much different from poison oak or stinging nettles. It’s a rather beautiful plant that has fern-like qualities. The leaves are green and oval, with a point on the top of the leaf. Each reddish stem contains seven to 13 leaves, running in pairs.

Poison sumac

The plant typically grows as a tall shrub or a smaller tree, growing in riparian areas. Although this plant is more common on the East Coast and some areas of the Midwest, we can find it here in Southern California.

A rash from poison sumac looks similar to that of poison oak. The treatment is much the same for all three of these plants mentioned.

I’ve been told there is poison sumac in Bouquet Canyon around the Falls area. I haven’t personally experienced this, but my daughter was hiking there last year, and after consulting a dermatologist, she was told it was caused by poison sumac. Then again, it might have just been a “rare foot condition.”

There are many other plants that can be dangerous to touch, ingest, burn, etc. – too many to list here. My emphasis here has been mostly on poison oak because it’s the most common in our natural areas and parks, and to promote awareness of the other poisonous plants that you might encounter while hiking or just being out in the open spaces of nature.

Always carry a container of hand sanitizer with you. Using it as soon as you realize you’ve come into contact with any of these plants will help alleviate the symptoms.

Enjoy your summer safely.

Mari Carbajal is a docent-naturalist at the Placerita Canyon Nature Center.