Black greasewood
Sarcobatus vermiculatus
Oxalate poisoning can be fatal to livestockColorado · 154 profiles · 462 photographs
Native volunteers
Native plants that can volunteer or spread where they are not wanted. Their ecological value and their hazards deserve separate consideration. Regional and taxonomic limits are explained in the profiles.
Biggest concerns · Coverage: all 82 state-list entries · Exposure and safety guide · Learn to use this guide
Native volunteers
29 plants
Broom snakeweed
Gutierrezia sarothrae
Livestock poisoning and abortion risk when heavily eaten
Buffalobur
Solanum rostratum
Sharp spines; toxic to livestock
Canada goldenrod
Solidago canadensis
Spreads by roots and seed
Catchweed bedstraw
Galium aparine
Hooked hairs and burrs cling to fur and clothing
Common blue violet
Viola sororia
A native volunteer; identify the species before removing
Common ragweed
Ambrosia artemisiifolia
Pollen allergy; skin irritation
Common sunflower
Helianthus annuus
Listed non-toxic to dogs & cats
Curlycup gumweed
Grindelia squarrosa
Sticky resin and conditional selenium concern
Foxtail barley
Hordeum jubatum
Barbed seed awns injure animals
Giant ragweed
Ambrosia trifida
Allergenic pollen and strong competition in disturbed ground
Golden banner
Thermopsis divaricarpa
May poison livestock
Hemp dogbane
Apocynum cannabinum
Cardiac-glycoside poisoning hazard for people and animals
Horseweed
Erigeron canadensis
Fast windborne spread; some populations resist herbicides
Low larkspur
Delphinium nuttallianum
Serious livestock and pet poisoning hazard
Meadow death camas
Toxicoscordion venenosum
Potentially fatal ingestion; onion-like bulbs
Netseed lambsquarters
Chenopodium berlandieri
A fast-growing volunteer; pet toxicity remains unresolved
Prairie sage
Artemisia ludoviciana
Spreading roots; pet evidence gap
Showy milkweed
Asclepias speciosa
Toxic if eaten
Silverleaf nightshade
Solanum elaeagnifolium
Toxic leaves and berries; persistent spreading roots
Snow-on-the-mountain
Euphorbia marginata
Latex can damage skin and eyes; toxic if eaten
Spotted spurge
Euphorbia maculata
Milky sap can injure skin and eyes; keep pets from chewing
Stinging nettle
Urtica dioica
Stinging hairs; this profile covers a taxonomic complex
Tall larkspur
Delphinium barbeyi
Serious livestock and pet poisoning hazard
Western poison ivy
Toxicodendron rydbergii
Skin-rash oil can travel on pet fur
Western ragweed
Ambrosia psilostachya
A persistent perennial ragweed; allergy detail still under review
Western water hemlock
Cicuta douglasii
Potentially fatal poisoning; wetland look-alike danger
Western whorled milkweed
Asclepias subverticillata
High livestock toxicity
White locoweed
Oxytropis sericea
Toxic to livestockRead with an AI assistant · Markdown and sources
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