Poisonous Outdoor Plants - Field Plants

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This section lists a variety of plants, many of them considered weeds that are known to cause livestock poisoning. Livestock poisoning can occur easily because the animals often ingest large quantities when grazing or when being fed hay or silage.

Many of the plants listed below have not been known to cause human poisoning. However, as more urban people unfamiliar with wild plants spend more of their time getting back to nature, the potential for human poisoning increases.

In most cases, large quantities of the plant need to be ingested to cause poisoning. Livestock are also susceptible to poisoning by some plants that are able to accumulate toxic materials such as nitrates and selenium; however, these plants are not listed here.

..Plant..Poisonous Part..Type of Poisoning/
..Toxic Agent
Triglochin maritima and
T. palustris
All partsInternal poisoning: cyanogenetic properties
Bahia oppositifolia
FoliageInternal poisoning: cyanogenetic glycoside
Black henbane
Hyoscycamus niger
All parts, especially rootsInternal poisoning: several alkaloids (mainly hyoscyamine)
Bittersweet (climbing nightshade)
Solanum dulcamara
Immature fruit, leavesInternal poisoning: solanine
Ranunculus spp.
All parts, except seeds; toxicity lost on drying.Internal poisoning: dermatitis/protoanemonin
Xanthium strumarium
Seeds, seedlingsInternal poisoning: hydroquinone
Docks, sorrelsLeaves, stemsInternal poisoning: soluble oxalates
Rumex spp.
Dogbane family
Indian hemp
Apocynum cannabinum
All partsInternal poisoning: resins and glycosides (primarily cymarin)
Spreading dogbane
Apocynum androsaemifolium
All parts, especially rhizomesInternal poisoning: resins and glycosides (primarily apocynamarin)
False ragweed
Iva xanthifolia
Field bindweed
(Wild morning glory)
Convolvulus arvensis
SeedsInternal poisoning
Golden bean
Thermopsis rhombifolia
Seeds, leavesInternal poisoning: quinolizidine alkaloids
Sarcobatus vermiculatus
All partsInternal poisoning: soluble oxalates
Green tansy mustard
Descurainia pinnata
All partsInternal poisoning: unknown
Ground ivy
Glechoma hederacea
All partsInternal poisoning: volatile oils
Senecio integerrimus,
S. vulgaris
All partsInternal poisoning: pyrrolizidine alkaloids
Jimson weed (thorn apple)
Datura stramonium
All parts, especially seeds and leavesInternal poisoning: solanaceous alkaloids
Locoweeds and milk vetches
Oxytropis and Astragalus spp.
All partsInternal poisoning: locaine
Malva parviflora
All partsInternal poisoning: malvalic and sterculic acids
Asclepias spp.
All partsInternal poisoning
Mustard family
Black mustard
Brassica nigra
All partsInternal poisoning: isothiocyanates
Canola (rapeseed)
Brassica napus
All parts, raw and in large quantitiesInternal poisoning: isothiocyanates
Indian mustard
Brassica juncea
All partsInternal poisoning: isothiocyanates
Wild mustard
Brassica kaber
Seed or podded plantsInternal poisoning: isothiocyanates
Wormseed mustard
Erysimum cheiranthoides
SeedsInternal poisoning: allyl isothiocyanate
Pasque flower (prairie crocus)
Anemone patens
All partsInternal poisoning: ranunculin
Prickly lettuce
Lactuca serriola
Young fresh plants are poisonous; mature plants and young stages after drying appear to be non-toxic.Internal poisoning: unknown
Ambrosia spp.
PollenHay fever
Artemisia spp.
All partsInternal poisoning:unknown
Silverleaf psoralea
Psoralea argophylla
SeedsInternal poisoning
Euphorbia spp.
SapDermatitis, internal poisoning
Thlaspi arvense
Seed, leavesInternal poisoning: allyl isothiocyanate
Tarweed (fiddleneck)
Amsinckia spp.
SeedsInternal poisoning: unknown liver toxin
Viper’s bugloss (blueweed)
Echium vulgare
Bristly hairs on leaves and stemsDermatitis

Other Documents in the Series

  Poisonous Outdoor Plants - Introduction
Poisonous Outdoor Plants - Garden Plants: Vegetables
Poisonous Outdoor Plants - Garden Plants: Flowers
Poisonous Outdoor Plants - Trees and Shrubs
Poisonous Outdoor Plants - Field Plants - Current Document
Poisonous Outdoor Plants - Forest Plants
Poisonous Outdoor Plants - Marsh Plants
Poisonous Outdoor Plants - References
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For more information about the content of this document, contact Barry Yaremcio.
This document is maintained by Jennifer Rutter.
This information published to the web on November 22, 2010.