The seedlings didn’t look like much, just some new weeds taking advantage of the unexpected September rain to get a head start of the winter growing season, but the tiny green sprouts popping up under the old roses in the author’s garden turned out to be Euphorbia terracina, also known as Carnation spurge. This was the first time this toxic, invasive, entirely unwelcome weed showed up in this location. The white sap was the giveaway and the author got it all over her hands before realizing what she was dealing with.
Not everyone is sensitive to terracina sap. Those who are may experience burning pain (not an exaggeration), swelling, and develop a painful rash that looks like the one caused by poison oak. The biggest danger for humans dealing with this weed is getting sap in the eyes, because it can cause temporary blindness and potentially damage the cornea.
Many members of the euphorbia family produce caustic sap, including popular ornamental plants like poinsettia, pencil cactus, and crown of thorns. It’s a good idea for anyone with young children or adventurous pets to avoid bringing euphorbias into the house or planting them in the garden.
The euphorbia’s sap helps members of this plant family deter animals and insects. Terracina spurge also produces allopathic chemicals that poison the soil, making it harder for the seeds of other plant species to grow, and helping this fast-growing weed form dense colonies.
This plant’s presence in the Santa Monica Mountains is still limited, but it is already a major problem and it is spreading. The National Park Service has been battling spurge in Solstice and Zuma canyons in Malibu for more than a decade. Terracina spurge has begun appearing in Topanga in recent years. Its presence is limited, so far, to Old Topanga Canyon, and a few spots along Topanga Canyon Boulevard, but this plant spreads rapidly. Its seeds are spring loaded and catapult in every direction.
Terracina spurge grows quickly, even in dry conditions or sandy soil, thrives in the local climate, which is similar to its native Mediterranean, and outcompetes everything else. The early rain helped give this weed a competitive edge over plants that germinate less quickly. It’s already off and running.
Spurge isn’t the only unwelcome plant invader taking advantage of the unusual combination of heavy rain and warm weather right now. All throughout the Santa Monica Mountains, castor beans are germinating and sprouting with wild abandon.
The castor bean, Ricinus communis, is by far the most toxic non native plant in the Santa Monica Mountains, and this plant is everywhere.
Our relationship with castor beans is complex and goes back thousands of years.
Traces of castor residue found in caves used by the San people of South Africa have been dated to 24,000 BCE. The ancient Egyptians used the castor bean plant as a medical treatment for a host of illnesses, so did the ancient Greeks.
The castor bean plant is sold in other areas as an ornamental garden plant, and it is also grown commercially for its oil, which is used in everything from paints and polishes to laxatives and cosmetics. Lipstick often contains castor bean oil. So do many skin and hair care products.
Castor oil is a traditional treatment for thinning hair, and is used to moisturize and soothe skin, and treat skin conditions like acne. The oil is heated to neutralize most of the ricin it contains—this is the same chemical synthesized during WWII to make deadly ricin gas. However, ricinoleic acid, the major component of castor oil, can cause skin irritations for people with sensitivities and is potentially toxic for animals even after being processed.
Just a couple of castor beans contains enough poison to kill a human or an animal, but all parts of the plant are toxic. There have been documented cases of castor bean plant poisoning in humans, cattle, horses, goats, sheep, pigs, rabbits, chickens, cats, dogs, and humans.
Symptoms of castor bean poisoning start with loss of appetite, dehydration, trembling, and end with bloody diarrhea, seizures, coma, and death.
There is no cure for ricin poisoning. The seeds are pretty and tempting for children to touch or eat. The leaves are large and decorative. Eliminating this plant as soon as it appears is the best way of preventing problems.
Seedlings are easier to root out than a massive, ten-foot-tall behemoth. The beans have the highest concentration of toxins but all parts of the castor bean plant are toxic, and should be handled with care. It’s a good idea to wear gloves and eye protection whenever dealing with potentially toxic weeds.
Tree tobacco, Nicotiana glauca, is another invasive weed that is popping up in abundance. This plant is especially abundant in the Palisades Fire burn zone.Tree tobacco is a fast-growing plant that has attractive, dusty gray-green foliage when it is young and pretty, tube-shaped yellow flowers that attract hummingbirds, which is why it was brought to California as a garden flower. It quickly grows into a rangy shrub that can be twenty feet tall. Tree tobacco escaped from gardens into the wild land interface and is now a major invasive species, forcing out native species like the native coastal and chaparral prickly pear cactus, and putting species that depend on the native plants at risk.
Like all tobaccos, N. glauca is a member of the nightshade family, and it is packed with alkaloids. This species can have high concentrations of anabasine, a highly toxic chemical compound that is similar to the nicotine found in commercial tobacco and can cause the symptoms as acute nicotine poisoning.
There are documented cases of people becoming extremely ill and even dying after mistaking tree tobacco shoots for edible plants, but the biggest risk is for young children and pets. Just a nibble of the leaves is enough to cause serious illness.
The toxins in tree tobacco can also be absorbed through the skin. Tree tobacco flowers abundantly and a single plant can produce millions of tiny seeds that are distributed by the wind. One plant can quickly become a forest of tree tobacco. Like the castor bean and the terracina spurge, this plant is much easier to remove when it is small,
Sacred datura, Datura wrightii, is a native plant, one that is a sacred plant to the Chumash. We’re including it in this article because it is highly toxic and often self-sows in the garden.
Sacred datura, also known as Western Jimson weed, thorn apple, and by the Chumash as Momoy, produces fragrant white trumpet flowers followed by spikey “apples.” (Pictured in the article opening.) If datura is growing in a place where it won’t be accidentally touched or consumed it can be a beautiful addition to the garden, but one that needs careful handling. Highly potent alkaloids in the leaves and sap can be absorbed through the skin or through cuts or scraps.
Datura is a powerful hallucinogen and also an extremely dangerous one. The compounds it contains include some of the most potent tropane alkaloids: atropine and scopolamine. Datura poisoning has landed many people in the hospital sometimes for weeks, and there are a number of documented fatalities.
There are three groups of people who are most likely to experience datura poisoning: teenagers trying to get high from consuming or smoking the plant or its seeds, young children attracted to the flowers, and gardeners who handled the plant without gloves.
Datura is an important native plant, but families with pets and young children may want to remove it or relocate away from play areas.
Our relationship with toxic plants is complex. Many of the plant alkaloids that can kill are useful in medicine. All of the species in this article are attractive, sometimes strikingly so. None of them, except for the datura, belong here. All of them have the ability to harm not only humans but animals, domestic and wild, but they are only a problem when they grow where they shouldn’t.
Making sure that children know to avoid touching or eating plants like datura and castor bean is just as important as teaching them about poison oak.
Keeping toxic plants away from children who are too young to understand but old enough to put things in their mouths, and from curious cats and perpetually hungry hens who can’t be taught how to recognize potential hazards, is also essential.
The biggest problem with toxic plants is that they so often hide in plain sight: along the road, or in the weedy patch at the bottom of the garden. Knowing what’s out there and how to recognize it is the best way to prevent problems.
It’s also a good idea to research plants before buying them for the garden. Castor bean wouldn’t be running amok in the hills if it hadn’t been imported as an ornamental garden plant. It’s impossible for individuals to undo that damage but we can eliminate toxic invasives from our own bit of earth.
Learning to recognize, respect, and avoid native toxic plants like datura and poison oak prevents problems from happening in the first place. Actively removing castor bean plants, terracina spurge, and tree tobacco from the garden or the roadside in front of our homes helps protect not only family members and family pets, but our wild neighbors and their habitat.
Just don’t forget to wear gloves!
