Gardening with Deb: Poisonous plants of Routt County |

Gardening with Deb: Poisonous plants of Routt County

Deb Babcock/For Steamboat Today

Deb Babcock

As a rule, plants considered poisonous to humans are also thought to be poisonous to animals. However, there have been instances where animals have been poisoned by plants considered safe for humans to eat.

Often, this happens because animals tend to eat a larger portion of plant materials than humans, thus the dose makes the poison. Normally, toxic plants in a range or pasture will not harm animals since they are unpalatable, but there are exceptions, such as larkspur.

Some of the more common poisonous plants that grow naturally and are planted in landscapes in the Steamboat area include the following:

• Death camas (Zigadenus spp.) is a grass-like perennial that grows from onion-like bulbs. It affects livestock early in the growing season because it is often the only green plant in a pasture. It causes human poisonings because people misidentify it as a wild onion.

• Water hemlock (Cicuta douglasii) is one the most toxic plants in the world, and it commonly grows along waterways in and around Steamboat Springs. The roots are especially toxic (symptoms appear within minutes), and death occurs in livestock or people very rapidly if they eat the roots. Be very careful with this plant; don’t allow it to grow in landscape settings.

• Poison hemlock (Conium maculata) is another highly poisonous plant that was imported to North America. The toxin is a violent convulsant that affects the central nervous system. The plant grows in waste areas along roadways. Both water hemlock and poison hemlock are members of the parsley family. The parsley family includes edible plants, like the yampa, and very toxic ones, like hemlock. Know your wild edibles well if you eat members of this plant family. If you suspect a poisoning, call the poison center immediately.

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• Monkshood (Aconitum species) is a beautiful wildflower that is also poisonous to livestock. It causes alkaloid poisoning, and while it is not commonly considered poisonous to humans, if enough is eaten, it will affect humans too.

• Larksur (Delphinium spp.) Two types of larkspur are common in Routt County. Low larkspur comes up early in the spring and reaches a height of approximately 8 inches; tall larkspur matures later and is commonly found in meadows and aspen groves. This plant kills more cattle in western ranges than any other poisonous plant. Larkspurs are one of the few poisonous plants that are palatable. Cattle like to eat it. Small quantities will not kill cattle, but consuming large amounts in a single time frame will. Again, as with monkshood, larkspur is a wildflower commonly cultivated in native gardens that would be toxic to people if they ate it. The toxicity of larkspur decreases as the plant matures.

• Lupine (lupinus spp.) More than 100 species of lupine grow in the United States, and many varieties have been developed for landscapes. Lupine causes abortion and disfigurement (cyclops’s and cleft palates) in newborn livestock. Poisonings are rare and only occur if livestock have inadequate grasses in pastures.

• Leafy spurge (Euphorbia esula) is both one of the area’s noxious weeds and is toxic to cattle, sheep and goats. Exposure to juice or sap from leafy spurge may produce skin irritation.

If you suspect someone has ingested a poisonous plant, call the Colorado Poison Center at 1-800-222-1222, or visit the Web at If a pet or ranch animal has ingested a toxic plant, contact your veterinarian right away. For pictures and detailed descriptions of plants poisonous to humans and livestock visit the Web at For lists of plants poisonous to pets, visit or

Deb Babcock is a Master Gardener through the CSU Exension Routt County. Questions? Call the CSU Cooperative Extension office at 879-0825 or email to:

Other poisonous plants of Routt County

• Blue flax (Linum species)

• Crown vetch (Coronilla varia)

• Nightshade (Solanum triflorum)

• Showy milkweed (Asclepias speciosa)

• Snakeweed (Gutierrezia sarothrae)

• Gumweed (Grindellia squarosa)

• Princeps plume (Stanleya pinnata)

• Hounds tongue (Cynoglossum)

• Horsebrush (Tetradymia canescens)