This list is meant only as a springboard for further study of poisonous plants; always consult with medical professionals when you suspect that you’ve wound up on the wrong end of an encounter with poisonous plants!
Bittersweet Nightshade: Common, But Uncommonly Toxic
Bittersweet nightshade is a very common weed and especially dangerous to have around kids, as they’re attracted to its brightly colored berries. Yet relatively few parents would be able to identify bittersweet nightshade on their property. This article also contains information about the vines more widely recognized as “bittersweet” (but which are quite distinct from bittersweet nightshade). Related to bittersweet nightshade (and equally toxic) is a specimen commonly grown by crafts enthusiasts: Chinese lanterns.
Foxglove: Beautiful But Toxic
Foxgloves grow well in dry shade — often a problematic area in the yard. But they are among the most toxic specimens commonly grown on the landscape. Do not grow them if small children will be spending time in the yard.
Laurels, Azaleas, Rhododendrons: Plants Toxic to Humans, Livestock
If you live in the country in eastern North America, you may have some mountain laurel growing in your backyard. Cultivars of mountain laurel are also sold at nurseries, including the beautiful ‘Minuet’ laurel shown in the picture. Like mountain laurel, azaleas and rhododendrons belong to the heath family — and are toxic. Don’t let pets nibble on any of these shrubs.
Castor Beans: Tropicals With Ricin
Castor bean is a tropical widely grown as an annual in northern climes, often as a potted plant for patios, decks or porches. The leaves, stalk and seed-heads are all attractive. The laxative, castor oil is derived from castor bean plants, but so is the deadly toxin, ricin.
Yew bushes can be grown in sun or shade. Their shade-tolerance gives landscape designers an important option in challenging areas. But those fleshy, bright red berries contain a seed that’s toxic.
Poison Sumac: Giving the Sumacs a Bad Name
The entries listed so far are all toxic if eaten. But in the case of some other weeds, all you have to do is touch them to be exposed to their toxicity — and come down with a rash. Poison sumac and poison ivy are examples. The former gives all sumac shrubs a bad name, despite the fact that most are quite harmless.
Poison Ivy: Leaves of Three, Let Them Be!
What makes poison ivy toxic? It’s an oil called, “urushiol.” Urushiol’s rash-inducing property has inspired a song, a DC Comics villain, and…well, much trepidation!
Touch-Me-Not: Jewelweed a Natural Remedy for Poison Ivy Rash
Jewelweed is also called, “touch-me-not”; but not because it’s toxic. Rather, jewelweed is considered a natural remedy for poison ivy rash. Like poison ivy, jewelweed is very common: both could very well be growing in your backyard. It’s easy to identify jewelweed, once you recognize its flower: it’s cornucopia-shaped, with a distinct little “tail.”
Like poison sumac and poison ivy, stinging nettles, as its name suggests, is not a plant you want to brush up against when working out in the yard. Your skin will burn with a painful itch for a short time after contact with its rash-inducing spines. Don’t confuse stinging nettles with dead nettles, a perennial used as a groundcover in shady areas.
The ASPCA lists yellow dock as being toxic to dogs. Like jewelweed, however, yellow dock (or “curly dock”) is a medicinal plant that can be used to counteract the discomfort caused by one of the toxic entries included on this page. Just as jewelweed alleviates the itch caused by poison ivy rash, curly dock can soothe skin inflamed by stinging nettles. Just roll one of the fresh, green leaves of curly dock between thumb and forefinger, to crush it into a juicy pulp; then rub it on your burning skin. The picture shows the mature flower-head of a yellow dock plant, after its blooms have dried and assumed a coffee color.
Lantana bears colorful flower clusters (orange is a popular color) and is commonly used (as an annual) by gardeners in cold climates as a hanging plant. Growers in warmer climes are familiar with lantana as a shrub, where this vigorous grower may even be invasive. But its invasiveness is not the only caveat that comes with growing lantana: one part of this plant “may be fatal if eaten,” according to the North Carolina Cooperative Extension.