Circular 636
Reviewed by Casey Spackman
College of Agricultural, Consumer and Environmental Sciences, New Mexico State University

Author: Professor, Department of Animal and Range Sciences, New Mexico State University. (Print friendly PDF)

Introduction

Poisonous plants represent one of the greatest hazards to livestock ranching on western rangelands. In addition to direct losses by death, there are those due to weight loss, poor reproductive performance, and poor health. Through scientific reports and practical experience, stockmen have learned to recognize poisonous plants and keep livestock losses to a minimum. Some of the things that can be done to prevent problems with poisonous plants are:

1. Know the poisonous plants. This is the first line of defense against toxic plants.
2. Practice good range management. To a limited degree, poisonous plants will always be present on rangelands, but the real danger is when the plants are eaten. Livestock poisoning is more often the result of poor range condition and poor management than the presence of poisonous plants. Most poisonous plants are unpalatable and will be eaten only if other good quality forage is not available.
3. Feed adequate mineral and vitamin A supplements. Livestock in poor health are more susceptible to many toxins than are healthy animals.
4. Provide adequate forage, especially during early spring or drought periods.
5. Avoid driving livestock through infested or poor condition range. Hungry animals lose their selectivity, and poor rangelands contain far more poisonous plants than those in good condition.
6. Use control measures—herbicides, grubbing, etc. —on heavy infestations of toxic plants.

The most common toxins in New Mexico poisonous plants are alkaloids, glycosides, minerals, nitrogenous compounds, oxalates and other organic acids, compounds causing photosensitivity, and resins or resinoids (see Tables 1 and 2).

Table 1. Plant Toxins and Their Effects on Livestock

Table 2. Distribution of Toxins in the Major Plant Families in New Mexico

Alkaloids. These are the most powerful poisons and produce strong physiological reactions, generally affecting the nervous system. The alkaloid is usually distributed throughout the plant and is active whether it is fresh or dry. There are no antidotes for alkaloid poisoning. Some of the common alkaloid-containing range plants are locoweeds (Astragalus spp.), larkspur (Delphinium spp.), groundsel (Senecio spp.), and lupine (Lupinus spp.).

Glycosides. Glycosides are compounds composed of a toxic agent combined with a sugar. The toxic agent is harmful when released from the glycosides. Cyanide (HCN, prussic acid) is the most common toxin in the glycosides. Glycoside levels in the plant are often related to environmental factors such as freezing, wilting, drought, and crushing. Cyanide is generally not retained in plant tissues after drying. Catclaw (Acacia greggii), chokecherry (Prunus virginiana), and johnsongrass (Sorghum halepense) are potential cyanide producers.

Minerals. Excessive absorption of certain minerals may be dangerous to livestock. Selenium is possibly the most important poisonous mineral in New Mexico. It may be found in some species of locoweed (Astragalus spp.), fourwing saltbush (Atriplex canescens), snakeweed (Xanthocephalum sarothrae), and asters (Aster spp.). Prince’s plume (Stanleya pinnata) grows only on seleniferous soils.

Nitrogenous compounds. Both range and crop plants may contain potentially toxic levels of nitrogenous compounds. Care must be taken during drought or after fertilizer or herbicide application. Nitrates are also toxic in dry material and silage. Nitrogenous compounds often are found in many species of the amaranth (Amaranthaceae), sunflower (Asteraceae), mustard (Brassicaceae), and gooscfoot (Chenopodiaceae) families.

Oxalates and organic acids. Many plants contain oxalates, but few species in New Mexico contain enough to be considered dangerous. Halogeton (Halogeton glomeratus) and dock (Rumex spp.) possess soluble oxalates that are corrosive to animal tissue. Non-ruminants are more susceptible to oxalate poisoning than ruminants because the large rumen capacity enables the animal to detoxify small amounts of soluble oxalates. Most cases of ruminant poisoning occur on poor condition rangelands.

Compounds causing photosensitivity. On certain occasions, animals become hypersensitive to light. Photodynamic pigments contained in horsebrush (Tetradymia spp.), lechuguilla (Agave lechuguilla), sacahuista (Nolina spp.), and puncture-vine (Tribulus terrestris) react with light to produce swelling about the head, blistering, and a sunburned appearance. Damage may be so severe that the lips, ears, and eyelids may be lost. Bacterial infection may also set in.

Resins or resinoids. These are highly complex organic compounds that are present in a number of plants. Resins are found in milkweeds (Asclepias spp.), marijuana (Cannabis sativa), water hemlock (Cieuta douglasii), and chinaberry tree (Melia azedaraeh).

Several noxious plants contain no poisonous compounds, but if grazed, cause injury through mechanical means. This is often by long awns or bristles (Aristida spp., Hordeum jubatum, Stipa spp.) or by stinging hairs (Urtiea spp.).

Poisonous Plants of New Mexico

There are at least 270 poisonous plants known to occur in New Mexico (Table 3). The following list includes all New Mexico range plants known to be poisonous or injurious to livestock or man, even though many of these do not pose a threat except in exceptional circumstances. Also included are a few very common poisonous ornamentals or garden plants that may occasionally escape. The major poisonous plants that are likely to cause problems and should be watched for are marked with an asterisk (*). The list is arranged in alphabetical order by plant family and scientific name. Indications of toxins and animals affected are only those reported and verified. The plants may be toxic to animals other than those listed.

Table 3. Number of Poisonous or Noxious Range Plants in New Mexico

Agavaceae

Agave lechuguilla Torr.
Common name: lechuguilla
Toxin: unknown substances producing hepatogenic photosensitization; saponins
Habitat: dry hills and plains
Animals affected: sheep, goats

Nolina microcarpa Wats.
Common name: beargrass, sacahuista
Toxin: unknown
Habitat: dry, rocky hills and plains
Animals affected: cattle, sheep, goats

Nolina terana Wats.
Common name: beargrass, sacahuista
Toxin: unknown
Habitat: dry, rocky hills and plains
Animals affected: cattle, sheep, goats

Amaranthaceae

*Amaranthus palmeri S. Wats.
Common name: pigweed, carelessweed, redroot amaranth
Toxin: nitrates
Habitat: gardens and old fields, waste areas
Animals affected: cattle, sheep, horses

*Amaranthus retroflexus L.
Common name: pigweed, carelessweed, redroot amaranth
Toxin: nitrates
Habitat: gardens and old fields, waste places
Animals affected: cattle, sheep, horses

Anacardiaceae

*Toxicodendron radicans (L.) Kuntze
Common name: poison ivy
Toxin: urushiol, a skin irritant
Habitat: moist areas at lower elevations, ravines
Animals affected: humans (dermatitis)

Apiaceae

Apium graveolens L.
Common name: celery
Toxin: nitrates (in the tops)
Habitat: waste ground
Animals affected: cattle

Berula erecta (Huds.) Cov.
Common name: water parsnip
Toxin: alkaloids
Habitat: waterways, wet habitats
Animals affected: cattle

*Cicuta douglasii (DC.) Coull. & Rose
Common name: water hemlock
Toxin: cicutoxin (alcohol)
Habitat: streams and marshes
Animals affected: all animals and humans

Conium maculalum L.
Common Name: poison hemlock
Toxin: alkaloids
Habitat: moist roadsides, ditches, edges of cultivated fields
Animals affected: all animals and humans

Daucus carow L.
Common name: wild carrot, Queen Ann’s lace
Toxin: nitrates
Habitat: waste areas
Animals affected: horses, cattle

Pastinaca sativa L.
Common name: parsnip
Toxin: unknown
Habitat: disturbed ground, cultivated areas
Animals affected: humans

Sium suave Walt.
Common name: water parsnip
Toxin: unknown
Habitat: marshes and wet soils
Animals affected: cattle, swine

Apocynaceae

Apocynum androsaemifolium L.
Common name: spreading dogbane
Toxins: resins, glycosides
Habitat: open places, coarse soils along streams, meadows and wooded hillsides
Animals affected: cats, dogs

Apocynum cannabinum L.
Common name: dogbane, hemp dogbane
Toxin: resins, glycosides
Habitat: open places, coarse soils along streams
Animals affected: cats, dogs

Nerium oleander L.
Common name: oleander
Toxin: glycosides
Habitat: common ornamental
Animals affected: cattle, sheep, horses, humans

Asclepiadaceae

*Asclepias asperula (Decne) Woodson
Common name: rough milkweed, spider antelopehorn
Toxins: resinoids, glycosides, alkaloids
Habitat: open dry plains, flats, desert swales, sandy or rocky hillsides with pinyon, juniper, or oak
Animals affected: sheep, cattle goats, horses, poultry

*Asclepias incamata L.
Common name: swamp milkweed
Toxin: resinoids, glycosides, alkaloids
Habitat: marshes
Animals affected: sheep, cattle, horses, poultry

*Asclepias latifolia (Torr.) Raf.
Common name: broadleaf milkweed
Toxin: resinoids, glycosides, alkaloids
Habitat: dry plains in sandy soils
Animals affected: sheep, goats

*Asclepias pumila Voil.
Common name: low whorled milkweed, plains whorled milkweed
Toxin: resinoids, glycosides, alkaloids
Habitat: plains, low hills
Animals affected: sheep, goats

*Asclepias speciosa Torr.
Common name: showy milkweed
Toxin: resinoids, glycosides, alkaloids
Habitat: prairies, open areas
Animals affected: sheep, goats

*Asclepias subvertkillata Vail.
Common name: whorled milkweed, western whorled milkweed
Toxin: resinoides, glycosides, alkaloids
Habitat: dry plains and foothills, waterways, irrigation canals
Animals affected: sheep, goats

*Asclepias venicillata L.
Common name: whorled milkweed
Toxin: resinoids, glycosides, alkaloids
Habitat: plains of northeastern New Mexico
Animals affected: sheep, cattle, horses

Asteraceae

Achillea millefolium L.
Common name: yarrow
Toxin: alkaloids and glycosides
Habitat: various
Animals affected: cattle, sheep, horses

Anthemis cotula L.
Common name: dog fennel, mayweed
Toxin: acrid substance irritating to mucous membranes
Habitat: disturbed soils, fields, waste places
Animals affected: poultry

Artemisia filifolia Torr.
Common name: sand sagebrush
Toxin: volatile oils
Habitat: sandy soils
Animals affected: horses

Artemisia spinescens (DC.) Eaton
Common name: bud sagebrush
Toxin: volatile oils
Habitat: dry plains, hills
Animals affected: cattle, sheep

Aster adscendens Lindt.
Common name: aster
Toxin: selenium
Habitat: mountain meadows
Animals affected: cattle, sheep

Aster coerulescens DC.
Common name: aster
Toxin: selenium
Habitat: wet ground, along streams
Animals affected: cattle, sheep

Aster commutatus Gray
Common name: aster
Toxin: selenium
Habitat: open fields, waste grounds
Animals affected: cattle, sheep

Aster ericoides L.
Common name: aster
Toxin: selenium
Habitat: meadows, open woods
Animals affected: cattle, sheep

Aster glaucoides Blake
Common name: gray aster
Toxin: selenium
Habitat: mountains
Animals affected: sheep

Aster laevis L.
Common name: smooth aster
Toxin: selenium
Habitat: scattered in dry to moist places
Animals affected: cattle, sheep

Aster occidentalis (Nutt.) Torr. & Gray
Common name: western aster
Toxin: selenium
Habitat: mountain meadows at moderate elevations
Animals affected: cattle, sheep

Aster pauciflorus Nutt.
Common name: fewheaded aster
Toxin: selenium
Habitat: widespread in saline soils
Animals affected: cattle, sheep

Baccharis pteronioides DC.
Common name: yerba-de-pasmo
Toxin: unknown
Habitat: dry, open hills
Animals affected: cattle, sheep

Bahia oppositifolia (Nutt.) DC.
Common name: bahia, plains bahia
Toxin: cyanogenetic glycoside
Habitat: dry soils of plains and hills
Animals affected: cattle, sheep

*Baileya multiradiata Harv. & Gray
Common name: desert baileya, desert marigold
Toxin: unknown
Habitat: sandy and gravelly soils in dry areas
Animals affected: sheep, goats

*Baileya pleniradiata Harv. & Gray
Common name: desert marigold, desert baileya
Toxin: unknown
Habitat: mesas, deserts
Animals affected: sheep, goats

Centaurea repens L.
Common name: Russian knapweed
Toxin: unknown
Habitat: fields, roadsides, waste places
Animals affected: horses

Centaurea solstitialis L.
Common name: yellow starthistle
Toxin: unknown
Habitat: waste grounds
Animals affected: horses

Chrysothamnus nauseosus (Pall.) Britton
Common name: rubber rabbitbrush
Toxin: unknown
Habitat: dry, open places at moderate and low elevations
Animals affected: cattle, sheep, horses

Conyza coulteri Gray
Common name: conyza
Toxin: unknown
Habitat: plains, valleys, alkaline soils
Animals affected: sheep

Flourensia cemua DC.
Common name: tarbush
Toxin: unknown
Habitat: dry plains, hills, mesas
Animals affected: sheep, goats

Grindelia squarrosa (Pursh) Dunal
Common name: curlycup gumweed
Toxin: selenium
Habitat: dry open places, prairies, plains, roadsides, fields
Animals affected: cattle, sheep, horses

*Gutierrezia microcephalum (DC.) Gray
Common name: broomweed, perennial snakeweed, turpentine weed, snakeweed, matchweed
Toxin: saponin
Habitat: dry plains, slopes, mesas
Animals affected: cattle, sheep, goats, swine, chicks, rabbits

*Gutierrezia sarothrae (Pursh) Britt. & Rusby
Common name: broom snakeweed, snakeweed, matchbrush, turpentine weed
Toxin: saponin
Habitat: dry stony plains, slopes, mesas
Animals affected: cattle, sheep, goats, swine, chicks, rabbits

*Haplopappus tenuisectus (Greene) Blake
Common name: burroweed
Toxin: tremetol (alcohol)
Habitat: dry slopes and mesas
Animals affected: cattle, sheep

*Helenium autumnale L.
Common name: sneezeweed, bitterweed
Toxin: unknown acrid substance
Habitat: moist low ground in lowlands and foothills
Animals affected: cattle, sheep

*Helenium hoopesii Gray
Common name: sneezeweed, orange sneezeweed
Toxin: glycoside (dugaldin)
Habitat: high mountain slopes and valleys, often forming dense stands in moist, sunny, undisturbed localities
Animals affected: cattle, sheep

*Helenium microcephalum DC.
Common name: sneezeweed
Toxin: unknown
Habitat: moist ground
Animals affected: cattle, sheep, horses, mules

*Hymenoxys odorata DC.
Common name: bitterweed, bitter rubberweed
Toxin: unknown
Habitat: semiarid range
Animals affected: sheep

*Hymenoxys richardsonii (Hook.) Cockerell
Common name: pingue, Colorado rubberweed, rubberweed
Toxin: unknown, may be associated with mineral imbalance
Habitat: dry, rocky, or clay soils of plains and mountain slopes
Animals affected: cattle, sheep, goats

*Isocoma wrightii (Gray) Rydb.
Common name: rayless goldenrod, jimmyweed, burrowweed
Toxin: tremetol (alcohol)
Habitat: river valleys, drainage areas, irrigation canals
Animals affected: cattle, sheep, horses

Lactuca serriola L.
Common name: wild lettuce
Toxin: unknown
Habitat: waste grounds, valleys, streamsides
Animals affected: cattle

*Oxytenia acerosa Nutt.
Common name: copperweed
Toxin: unknown
Habitat: alkaline soils in draws and streambeds, desert ranges
Animals affected: cattle, sheep

Psathyrotes annua (Nutt.) Gray
Common name: annual psathyrotes
Toxin: unknown
Habitat: dry, sandy, often alkaline soils, especially creekbeds, dry washes
Animals affected: sheep

*Psilostrophe sparsiflora (Gray) A. Nels.
Common name: paperflower
Toxin: unknown, induces kidney damage
Habitat: dry, open range
Animals affected: sheep

*Psilostrophe tagetinre (Nutt.) Greene
Common name: paperflower
Toxin: unknown, induces kidney damage
Habitat: dry, open range
Animals affected: sheep

Rudbeckia laciniata L.
Common name: golden glow, coneflower, thimble weed
Toxin: unknown
Habitat: moist, rich soils
Animals affected: swine, sheep

Rudbeckia hirta L.
Common name: black-eyed Susan
Toxin: unknown
Habitat: open slopes, meadows
Animals affected: cattle, swine

Sartwellia flaveriae Gray
Common name: sartwellia
Toxin: unknown
Habitat: alkaline soils, gypsum
Animals affected: cattle, sheep, goats

*Senecio douglasii DC. var. longilobus (Benth.) L. Benson
Common name: threadleaf groundsel
Toxin: pyrrolizidine alkaloids
Habitat: dry slopes, mesas, dry washes
Animals affected: cattle, sheep, horses, goats

*Senecio riddellii Torr. & Gray
Common name: Riddell’s groundsel
Toxin: pyrrolizidine alkaloids
Habitat: dry, sandy soils
Animals affected: cattle, sheep, horses, goats

Senecio spartioides Torr. & Gray
Common name: broom groundsel
Toxin: pyrrolizidine alkaloids
Habitat: valleys, plains, open areas, pine forests
Animals affected: cattle, sheep, horses, goats

Senecio vulgaris L.
Common name: common groundsel
Toxin: pyrrolizidine alkaloids
Habitat: gardens, disturbed ground
Animals affected: cattle, sheep, horses, goats

Sideranthus grindelioides (Nutt.) Rydb.
Common name: ironweed
Toxin: selenium
Habitat: dry plains, rocky hills
Animals affected: sheep

Tanacetum vulgare L.
Common name: common tansy
Toxin: ethereal oil; causes abortions
Habitat: roadsides, waste areas, ditchbanks,moist areas
Animals affected: cattle

*Tetradymia canescens DC.
Common name: horsebrush
Toxin: photosensitizing compounds
Habitat: dry desert and sagebrush range
Animals affected: sheep

*Tetradymia spinosa Torr. & Gray
Common name: spiny horsebrush
Toxin: photosensitzing compounds
Habitat: dry desert and sagebrush range
Animals affected: sheep

Viguiera annua (Jones) Blake
Common name: annual goldeneye
Toxin: unknown
Habitat: dry hills and mesas
Animals affected: cattle

*Xanthium spinosum L.
Common name: spiny cocklebur
Toxin: hydroquinone
Habitat: waste places, fields
Animals affected: cattle, sheep, fowl, swine

*Xanthium strumarium L.
Common name: cocklebur
Toxin: hydroquinone
Habitat: fields and waste places
Animals affected: cattle, sheep, horses, fowl, wines

Boraginaceae

Amsinckia intermedia Fisch & May
Common name: fiddleneck
Toxin: unknown
Habitat: dry, open, cultivated ground and waste areas
Animals affected: cattle, horses, swine

Cynoglossum officinale L.
Common name: hounds tongue
Toxin: unknown
Habitat: waste places in plains and hills
Animals affected: cattle

Brassicaceae

Barbarea vulgaris R. Br.
Common name: yellow rocket
Toxin: mustard oil
Habitat: wet meadows, waste places
Animals affected: horses

Brassica hirta Moench
Common name: white mustard
Toxin: cyanogenetic glycoside
Habitat: cultivated fields, waste areas
Animals affected: cattle, sheep

Brassica kaber Wheeler
Common name: charlock
Toxin: cyanogenetic glycoside
Habitat: grain fields, waste areas
Animals affected: cattle, sheep, swine

Brassica nigra Koch
Common name: black mustard
Toxin: goiterogenic glycoside
Habitat: cultivated fields
Animals affected: cattle

*Descurainia pinnata (Walt.) Britt.
Common name: tansy mustard
Toxin: unknown
Habitat: sandy soils
Animals affected: cattle

Raphanus raphanastrum L.
Common name: wild radish
Toxin: unknown
Habitat: cultivated areas, waste places
Animals affected: cattle

Stanleya pinnata (Pursh) Britt.
Common name: Prince’s plume
Toxin: selenium
Habitat: desert areas, dry plains and mesas
Animals affected: cattle, sheep

Thlaspi arvense L.
Common name: field pennycress
Toxin: cyanogenetic glycoside
Habitat: cultivated fields, waste areas
Animals affected: cattle

Campanulacea

Lobelia cardinalis L.
Common name: western cardinal flower
Toxin: alkaloids
Habitat: wet ground
Animals affected: cattle, sheep, goats

Cannabinaceae

Cannabis sativa L.
Common name: marijuana
Toxin: tetrahydrocannabinol
Habitat: waste places
Animals affected: cattle, sheep, horses, humans

Capparidaceae

Wislizenia refracta Engelm.
Common name: jackass clover
Toxin: unknown
Habitat: roadsides, fields
Animals affected: cattle

Caprifoliaceae

Sambucus mexicana Presl.
Common name: Mexican elder
Toxin: unknown
Habitat: valleys, streambanks, ornamental
Animals affected: cattle, swine

Sambucus pubens Michx.
Common name: stinking elder
Toxin: unknown
Habitat: streambanks
Animals affected: cattle, swine

Sambucus microbotrys Rydb.
Common name: Rocky Mountain red elder
Toxin: unknown, concentrated in root
Habitat: moist woods, 8,000–12,000 feet
Animals affected: cattle, swine

Caryophyllaceae

Agrostemma githago L.
Common name: com cockle
Toxin: cardiac glycoside
Habitat: cultivated fields, waste places
Animals affected: cattle, swine, poultry

*Drymaria pachyphylla Woot. & Standl.
Common name: inkweed, drymary
Toxin: unknown
Habitat: alkaline clay soils
Animals affected: cattle, sheep

Saponaria officinalis L.
Common name: bouncing bet, soapwort
Toxin: saponin
Habitat: waste areas, roadsides
Animals affected: sheep, rabbits

Saponaria vaccaria L.
Common name: cow cockle
Toxin: saponin
Habitat: waste areas, roadsides
Animals affected: sheep, rabbits

Chenopodiaceae

Atriplex canescens (Pursh) James
Common name: four-wing saltbush
Toxin: selenium
Habitat: dry plains, canyons
Animals affected: cattle, sheep

Atriplex nuttallii Wats. subsp. cuneata (A. Nels.)
Common name: Nuttall saltbush
Toxin: selenium
Habitat: dry hills and slopes
Animals affected: cattle, sheep

Atriplex rosea L.
Common name: red orache, red shadscale
Toxin: selenium
Habitat: waste areas
Animals affected: cattle, sheep

Bassia hyssopifolia (Pall.) Kuntze
Common name: bassia
Toxin: oxalates
Habitat: dry, saline areas
Animals affected: sheep

*Chenopodium album L.
Common name: lambsquarter, goosefoot
Toxin: nitrates
Habitat: waste places
Animals affected: cattle, sheep, horses

Chenopodium ambrosioides L.
Common name: goosefoot
Toxin: antihelminthic oil
Habitat: waste places
Animals affected: geese

Chenopodium glaucum L.
Common name: oakleaf goosefoot
Toxin: nitrates
Habitat: waste places
Animals affected: cattle, sheep

*Halogeton glomeratus (Bieg.) C.A. Mey.
Common name: halogeton, barilla
Toxin: oxalates
Habitat: dry saline plains and alkaline areas, roadsides
Animals affected: cattle, sheep

Kochia scoparia (L.) Schrad.
Common name: summer cypress, kochia
Toxin: photosensitizing compounds
Habitat: dry soils, roadsides, waste places
Animals affected: cattle, sheep, horses

Salsola iberica Sennen Pau.
Common name: Russian thistle, tumbleweed
Toxin: nitrates
Habitat: dry soils of plains and foothills
Animals affected: cattle, sheep, horses

*Sarcobatus vermiculatus (Hook.) Torr.
Common name: greasewood
Toxin: oxalates
Habitat: alkaline flats or saline areas at low elevations
Animals affected: sheep, sometimes cattle

Suckleya suckleyana (Torr.) Rydb.
Common name: poison suckleya
Toxin: hydrocyanic acid
Habitat: moist ground, near ponds and reservoirs
Animals affected: cattle, sheep

Cyperaceae

Scirpus americanus Pers.
Common name: bulrush
Toxin: unknown, suspected of producing pulmonary emphysema
Habitat: wet or moist ground
Animals affected: sheep, sometimes cattle

Equisefaceae

*Equisetum arvense L.
Common name: horsetail, scouring rush
Toxin: alkaloids
Habitat: sandy or gravelly soils along streams, moist fields, meadows
Animals affected: cattle, sheep, horses, goats

*Equisetum hiemale L.
Common name: scouring rush, horsetail
Toxin: alkaloids
Habitat: low moist areas, mostly along streams
Animals affected: cattle, sheep, horses, goats

*Equisetum laevigatum R. Br.
Common name: smooth horsetail
Toxin: thiaminase
Habitat: marshes, alluvial thickets, cultivated areas
Animals affected: cattle, sheep, horses, goats

Euphorbiacecae

Croton texensis (Klotz.) DC.
Common name: Texas croton
Toxin: croton oil (caustic)
Habitat: roadsides, fields, dry streambeds
Animals affected: cattle, sheep, horses

Euphorbia albomarginata Torr. & Gray
Common name: spurge
Toxin: unknown photosensitizing substance
Habitat: dry flats and slopes
Animals affected: cattle, sheep

Euphorbia esula L.
Common name: leafy spurge
Toxin: unknown acrid principle
Habitat: waste areas
Animals affected: sheep, horses

Euphorbia maculata L.
Common name: eyebane, spotted spurge
Toxin: unknown photosensitizing substance
Habitat: fields, slopes, canyons
Animals affected: sheep

Euphorbia marginata Pursh
Common name: snow-on-the-mountain
Toxin: unknown acrid principle
Habitat: plains, ornamental
Animals affected: cattle, humans

Euphorbia prostrata Alt.
Common name: euphorbia
Toxin: unknown acrid principle
Habitat: open plains and waste areas
Animals affected: cattle

Reverchonia arenaria Gray
Common name: reverchonia
Toxin: unknown
Habitat: dry, sandy ground
Animals affected: sheep

Fabacecae

*Acacia constricta Benth.
Common name: whitehorn acacia
Toxin: cyanogenetic glycoside
Habitat: dry slopes and mesas
Animals affected: cattle

*Acacia gregii Gray
Common name: catclaw acacia
Toxin: cyanogenetic glycoside
Habitat: along streams and washes; southern New Mexico
Animals affected: sheep

Astragalus albulus Woot. & Standl.
Common name: Cibola milkvetch
Toxin: selenium
Habitat: clay flats, low hills, sandstone soils
Animals affected: cattle, sheep, horses

Astragalus allochrous Gray var. allochrous
Common name: halfmoon locoweed
Toxin: swainsonine
Habitat: dry slopes, plains, and valleys
Animals affected: cattle, sheep, horses

*Astragalus allochrous Gray var. playanus (M.E. Jones) Isely
Common name: Wooton locoweed
Toxin: alkaloid (locoine)
Habitat: plains, slopes, valleys
Animals affected: cattle, sheep, horses

Astragalus bisulcatus (Hook.) Gray var. bisulcatus
Common name: two-grooved milkvetch
Toxin: selenium
Habitat: plains and bottomlands, sagebrush zones
Animals affected: cattle, sheep, horses

Astragalus bisulcatus var. haydenianus (Gray) Barneby
Common name: two-grooved milkvetch
Toxin: selenium
Habitat: plains, dry slopes, sagebrush zone
Animals affected: cattle, sheep, horses

Astragalus canadensis L.
Common name: Canada milkvetch
Toxin: swainsonine
Habitat: moist ground or sometimes rocky slopes
Animals affected: cattle, sheep, horses

Astragalus confertiflorus Gray
Common name: yellow milkvetch
Toxin: selenium
Habitat: rocky slopes
Animals affected: cattle, sheep, horses

Astragalus drummondii Hook.
Common name: Drummond milkvetch
Toxin: swainsonine
Habitat: plains and hillsides, brush places
Animals affected: cattle, sheep, horses

Astragalus emoryanus (Rydb.) Cory
Common name: Emory milkvetch
Toxin: alkaloid, produces locoism when found on limestone soils or red sandy soils
Habitat: rocky hillsides, canyons, disturbed areas
Animals affected: cattle, sheep, goats

Astragalus flavus Torr. & Gray
Common name: yellow milkvetch
Toxin: selenium
Habitat: rocky slopes, low hills
Animals affected: cattle, sheep, horses

*Astragalus lentiginosus Hook var. lentiginosus
Common name: blue loco
Toxin: swainsonine
Habitat: rocky slopes, canyons, mesas
Animals affected: cattle, sheep, horses

*Astragalus lentiginosus Hook. var. diphysus (Gray) M.E. Jones
Common name: blue loco, rattleweed
Toxin: swainsonine
Habitat: rocky slopes, canyons, mesas
Animals affected: cattle, sheep, horses

*Astragalus mollissimus Torr. var. mollissimus
Common name: woolly locoweed
Toxin: swainsonine
Habitat: open plains and valleys
Animals affected: cattle, sheep, horses

*Astragalus mollissimus var. earlei (Rydb.) Tidestrom
Common name: woolly locoweed
Toxin: swainsonine
Habitat: dry slopes and plains
Animals affected: cattle, sheep, horses

*Astragalus nothoxys Gray
Common name: beaked milkvetch
Toxin: alkaloid swainsonine
Habitat: open slopes, sandy areas, among oak and juniper
Animals affected: cattle, sheep, horses

Astragalus oocalycis M.E. Jones
Common name: locoweed
Toxin: selenium
Habitat: dry hills, plains, valleys
Animals affected: cattle, sheep, horses

Astragalus pattersonii Gray
Common name: Patterson locoweed
Toxin: selenium
Habitat: dry plains and hillsides, in alkaline or seleniferous soils
Animals affected: cattle, sheep, horses

Astragalus pectinatus G. Don
Common name: tine-leaved milkvetch
Toxin: selenium
Habitat: variety of habitats
Animals affected: cattle, sheep, horses

Astragalus praelongus Sheld. var. praelongus
Common name: stinking milkvetch
Toxin: selenium
Habitat: variety of habitats
Animal affected: cattle, sheep, horses

Astragalus prcelongus var. ellisire (Rydb.) Barneby
Common name: Ellis milkvetch
Toxin: selenium
Habitat: variety of habitats, widespread
Animals affected: cattle, sheep, horses

Astragalus racemosus Pursh var. racemosus
Common name: alkali milkvetch
Toxin: selenium
Habitat: barren slopes, alluvial areas, alkaline soils
Animals affected: cattle

Astragalus racemosus var. longisetus M.E. Jones
Common name: alkali milkvetch
Toxin: selenium
Habitat: eroded slopes, along streams
Animals affected: cattle

Astragalus tephrodes Gray
Common name: silverline locoweed
Toxin: swainsonine
Habitat: rocky slopes to sandy plains

*Astragalus thurberi Gray
Common name: Thurber milkvetch
Toxin: alkaloid (locoine)
Habitat: plains, valleys, open slopes
Animals affected: cattle, sheep, horses

Cassia fasiculata Michx. var. fasiculata
Common name: partridge-pea
Toxin: unknown
Habitat: dry fields and hillsides
Animals affected: cattle, sheep, horses

Cassia fasiculata var. rostrata (Woot. & Standl.) B.L. Turner
Common name: partidge-pea
Toxin: unknown
Habitat: restricted to the plains of east-central New Mexico
Animals affected: cattle, sheep, horses

Crotalaria sagittalis L.
Common name: rattlebox, crotalaria
Toxin: unknown
Habitat: sandy soil near streams
Animals affected: horses

Lathyrus polymorphus subsp. incanus (J.G. Sm. & Rydb.) C.L. Hitchc.
Common name: wild pea
Toxin: alpha-, gamma-diaminobutyric acid
Habitat: dry plains, sandy banks, washes
Animals affected: horses

Lotus comiculatus L.
Common name: birdsfoot trefoil
Toxin: cyanogenetic glycoside
Habitat: sandy roadsides
Animals affected: cattle, sheep, horses

*Lupinus alpestris A. Nels.
Common name: lupine, bluebonnet
Toxin: alkaloids
Habitat: mountains
Animals affected: cattle, sheep

*Lupinus argenteus Pursh var. argenteus
Common name: silvery lupine
Toxin: alkaoids
Habitat: meadows, open woods
Animals affected: cattle, sheep, deer

*Lupinus argenteus var. stenophyllus (Torr. & Gray) Davis
Common name: silvery lupine
Toxin: alkaloids
Habitat: meadows, open woods
Animals affected: cattle, sheep, deer

*Lupinus caudatus Kell.
Common name: Kellogg’s spurred lupine, tailcut lupine
Toxin: alkaloids
Habitat: exposed hillsides
Animals affected: cattle

Medicago hispida Gaertn.
Common name: burclover
Toxin: photosentization compounds
Habitat: waste areas
Animals affected: cattle, sheep, swine

Medicago sativa L.
Common name: alfalfa, lucerne
Toxin: saponin, photosensitization compounds
Habitat: cultivated and escaping
Animals affected: cattle, sheep, chicks, swine

Melilotus albus Desv.
Common name: white sweetclover
Toxin: dicoumarin
Habitat: waste areas, fields
Animals affected: cattle

Melilotus officinalis Lam.
Common name: yellow sweetclover
Toxin: dicoumarin
Habitat: waste areas, fields
Animals affected: cattle, sheep, horses

*Oxytropis lambertii Pursh
Common name: Lambert’s crazyweed
Toxin: unknown alkaloid, produces locoism
Habitat: plains, mountain slopes
Animals affected: cattle, sheep, horses

*Oxytropis sericea Torr. & Gray
Common name: white loco, silky crazyweed
Toxin: alkaloids, produces locoism
Habitat: open slopes, widespread
Animals affected: cattle, sheep, horses

Pisum sativum L.
Common name: garden pea
Toxin: unknown
Habitat: gardens
Animals affected: cattle, sheep

Poinciana gilliesii Hook
Common name: bird of paradise
Toxin: unknown, green seed pods are gastrointestinal irritants
Habitat: around dwelling sites, waste areas
Animals affected: cattle

Prosopis glandulosa Torr.
Common name: mesquite
Toxin: unknown, may cause a nutritional deficiency
Habitat: plains, prairies, river valleys
Animals affected: cattle

Psoralea argophylla Pursh
Common name: scurf pea
Toxin: unknown
Habitat: plains and hills
Animals affected: cattle, sheep

Psoralea tenuiflora Pursh
Common name: scurf pea, Indian turnip
Toxin: unknown
Habitat: dry plains, low hills
Animals affected: cattle, horses

Robinia pseudoacacia L.
Common name: black locust
Toxin: unknown
Habitat: along roadsides, escaped from cultivation
Animals affected: cattle, sheep, horses, poultry

Sophora secundiflora (Ort.) Lag.
Common name: mescal bean, frijolito
Toxin: alkaloids
Habitat: along limestone bluffs, gravelly outwashes
Animals affected: cattle, sheep, goats

Sophora sericia Nutt.
Common name: silky sophora
Toxin: alkaloids
Habitat: dry fields and plains
Animals affected: horses

Thermopsis montana Nutt.
Common name: mountain golden pea
Toxin: alkaloids
Habitat: mountain valleys and clearings
Animals affected: cattle

Thermopsis rhombifolia Rich.
Common name: prairie thermopsis
Toxin: alkaloids
Habitat: dry, sandy soils of hills and plains
Animals affected: cattle, horses

Trifolium hybridum L.
Common name: alsike clover
Toxin: photosensitizing compound
Habitat: meadows, waste areas
Animals affected: cattle, sheep, horses, swine

Trifolium pratense L.
Common name: red clover
Toxin: unknown
Habitat: fields and waste areas
Animals affected: cattle, sheep, horses

Trifolium repens L.
Common name: white clover
Toxin: cyanogenetic glycoside
Habitat: fields and waste areas
Animals affected: newborn pigs

Vicia villosa Roth
Common name: hairy vetch, wintervetch
Toxin: photosensitizing compound
Habitat: cultivated areas
Animals affected: cattle, horses

Fagaceae

*Quercus gambelii Nutt.
Common name: Gambeloak
Toxin: tannins
Habitat: canyons and mountain slopes
Animals affected: cattle, sheep, goats

*Quercus havardii Rydb.
Common name: Havard shinoak, shinnery
Toxin: tannins
Habitat: sandy plains
Animals affected: cattle, sheep

Fumariaceae

*Corydalis aurea Willd.
Common name: golden corydalis
Toxin: alkaloids
Habitat: damp slopes and plains
Animals affected: cattle, sheep

Gentianaceae

Centaurium calycosum Fern.
Common name: mountain pink
Toxin: unknown
Habitat: boggy or marshy places
Animals affected: sheep, goats

Hypericaceae

Hypericum formosum H.B.K.
Common name: southwestern St. Johnswort
Toxin: photosensitizing compounds
Habitat: moist soil in damp meadows
Animals affected: cattle, sheep, horses, goats

Iridaceae

Iris missouriensis Nutt.
Common name: Rocky Mountain iris
Toxin: unknown
Habitat: open meadows in the higher mountains
Animals affected: calves

Juncaginaceae

*Triglochin maritima L.
Common name: arrowgrass
Toxin: hydroqanic acid
Habitat: marshy ground
Animals affected: cattle, sheep

*Triglochin palustris L.
Common name: arrowgrass
Toxin: hydroqanic acid
Habitat: marshy ground
Animals affected: cattle, sheep

Lamiaceae

Lamium amplexicaule L.
Common name: henbit, dead nettle
Toxin: unknown
Habitat: waste areas
Animals affected: cattle, sheep, horses

Salvia reflexa Hornem.
Common name: annual sage, mintweed
Toxin: nitrates
Habitat: rocky slopes, open woods
Animals affected: cattle

Liliaceae

Asparagus officinalis L.
Common name: asparagus
Toxin: unknown compound in fruits
Habitat: valleys, roadsides, loose or sandy soils
Animals affected: cattle and dairy cattle

*Veratrum californicum Durarid
Common name: false hellebore, cornlily
Toxin: alkaloids
Habitat: moist meadows in the mountains
Animals affected: cattle, sheep, fowl

*Zigadenus venenosus Pursh
Common name: death camas
Toxin: alkaloids
Habitat: wooded slopes in the mountains
Animals affected: cattle, horses, swine, fowl

*Zigadenus gramineus Rydb.
Common name: death camas
Toxin: alkaloids
Habitat: wooded slopes and open ground
Animals affected: cattle, sheep, horses

*Zigadenus paniculatus (Nutt.) Wats
Common name: death camas
Toxin: alkaloids
Habitat: open grassy or rocky plains and hills
Animals affected: cattle, horses, swine

Linaceae

Linum neomexicanum Greene
Common name: New Mexico yellow flax
Toxin: saponin, glycoside
Habitat: wooded mountain slopes
Animals affected: cattle

Linum usitatissimum L.
Common name: flax
Toxin: cyanogenetic glycoside
Habitat: waste areas around cultivated areas
Animals affected: cattle

Loranthaceae

Phoradendron flavescens (Pursh) Nutt. var. flavescens
Common name: mistletoe
Toxin: pressor amines, phenylethylamine, tyramine
Habitat: parasitic on cottonwood and other decidous trees
Animals affected: cattle

Phoradendron flavescens var. macrophyllum Englem.
Common name: mistletoe
Toxin: pressor amines, phenylethylamine, tyramine Habitat: parasitic on cottonwood and other decidous trees
Animals affected: cattle

Phoradendron flavescens var. orbiculatum Engel.
Common name: mistletoe
Toxin: pressor amines, phenylethylamine, tyramine
Habitat: parasitic on oak
Animals affected: cattle

Phoradendron flovescens var. villosum (Nutt.) Engelm.
Common name: mistletoe
Toxin: pressor amines, phenylethylamine, tyramine
Habitat: parasitic on decidous trees
Animals affected: cattle

Malvaceae

Gossypium barbadense L.
Common name: sea-island cotton
Toxin: gossypol in seeds
Habitat: cultivated
Animals affected: cattle, sheep, horses

Malva parviflora L.
Common name: mallow, cheeseweed
Toxin: fatty acids (malvalic and sterculic)
Habitat: waste areas
Animals affected: cattle, sheep, horses

Meliaceae

Melia azedarach L.
Common name: chinaberry tree
Toxin: resins, especially in fruits
Habitat: waste areas, ornamental
Animals affected: cattle, sheep, horses

Moraceae

Maclura pomifera Schneid
Common name: Osage-orange
Toxins: unknown compounds in fruit
Habitat: waste areas and arroyos
Animals affected: cattle, sheep, horses

Oxalidaceae

Oxalis corniculota L.
Common name: creeping woodsorrel
Toxin: oxalates
Habitat: moist waste areas, often in lawns
Animals affected: sheep

Papaveraceae

Argemone mexicana L.
Common name: Mexican poppy
Toxin: alkaloids
Habitat: waste areas
Animals affected: cattle, sheep, horses, fowl

Argemone polyanthemos (Fedde) G. Ownbey
Common name: prickley poppy
Toxin: alkaloids
Habitat: dry plains, waste areas
Animals affected: cattle, sheep, horses, fowl

Papaver nudicaule L. var. radicatum (Rottb.) DC.
Common name: Iceland poppy
Toxin: alkaloids
Habitat: open slopes and summits
Animals affected: cattle, sheep, horses

Papaver somniferum L.
Common name: common poppy
Toxin: alkaloids
Habitat: ornamental
Animals affected: cattle, sheep, horses

Pinaceae

Pinus ponderosa Laws.
Common name: Western yellow pine, ponderosa pine
Toxin: unknown compounds in leaves
Habitat: mountain areas
Animals affected: cattle

Poaceae

Agropyron spp.
Common name: wheatgrass
Toxin: ergot infestation of seedheads
Habitat: rangeland and pastures
Animals affected: cattle, sheep, horses, humans

Aristida spp.
Common name: red three-awn
Toxin: awns are mechanically injurious
Habitat: plains and rocky slopes
Animals affected: cattle, sheep, horses

Avena fatua L.
Common name: wild oats
Toxin: nitrates
Habitat: cultivated land and waste areas
Animals affected: cattle, sheep, horses

Avena sativa L.
Common name: cultivated oats
Toxin: nitrates, photosensitizing compounds, grass tetany
Habitat: open ground, grasslands, waste areas
Animals affected: cattle, sheep, horses

Bouteloua spp.
Common name: grama grasses
Toxin: low levels of cyanide
Habitat: plains
Animals affected: cattle

Bromus diandrus Roth
Common name: ripgut brome
Toxin: mechanical injury from mature awns
Habitat: weedy ground
Animals affected: cattle, sheep

Bromus inermis Leyss.
Common name: smooth brome
Toxin: ergot infestation of seed heads
Habitat: mountain slopes and meadows
Animals affected: cattle, sheep, horses

Bromus rubens L.
Common name: foxtail chess, red brome
Toxin: mechanical injury from mature awns
Habitat: dry hills and waste areas
Animals affected: cattle, sheep

Bromus tectorum L.
Common name: cheatgrass, down cheat
Toxin: mechanical injury from mature awns; may also cause ergot poisoning
Habitat: roadsides and waste areas
Animals affected: cattle

Cynodon dactylon L. Pers.
Common name: Bermudagrass
Toxin: photosensitizing compound, hayfever
Habitat: waste areas; widespread
Animals affected: cattle

Elymus spp.
Common name: wildrye
Toxin: ergot infestation
Habitat: mountain slopes, plains
Animals affected: cattle

Eragrostis cilianensis (All.) Lin.
Common name: lovegrass, stinkgrass
Toxin: unknown
Habitat: cultivated or waste areas
Animals affected: horses

Festuca arundinacea Schreber
Common name: tall fescue
Toxin: alkaloids, fescue foot
Habitat: pastures
Animals affected: cattle

Glyceria striata (Lam.) Hitchc.
Common name: fowl mannagrass
Toxin: cyanogenetic compounds
Habitat: plains and foothills
Animals affected: cattle, sheep, horses

Hilaria jamesii (Torr.) Benth.
Common name: galleta
Toxin: ergot infestation of sheedheads
Habitat: plains and foothills
Animals affected: cattle, sheep, horses

Hilaria mutiea (Buckl.) Benth.
Common name: tobosa
Toxin: ergot infestation of seedheads
Habitat: plains and foothills
Animals affected: cattle, sheep, horses

Hordeum jubatum L.
Common name: foxtail barley
Toxin: mechanical injury from mature awns
Habitat: plains and open slopes
Animals affected: cattle, sheep, horses

Hordeum vulgare L.
Common name: barley
Toxin: mechanical injury from mature awns
Habitat: waste areas
Animals affected: cattle, swine, dogs, poultry

Lolium perenne L.
Common name: perennial ryegrass
Toxin: ergot infestation of seed heads
Habitat: meadows, waste areas
Animals affected: cattle

Panicum antidotale Retz.
Common name: blue panicum
Toxin: nitrates
Habitat: rangelands
Animals affected: cattle

Panicum capillare L.
Common name: witchgrass
Toxin: nitrates
Habitat: roadsides, waste places
Animals affected: cattle

Panicum coloratum L.
Common name: Kleinegrass
Toxin: photosensitivity
Habitat: pastures
Animals affected: sheep

Paspalum dilatatum Poir.
Common name: dallisgrass
Toxin: ergot infestation of seed heads
Habitat: irrigated pastures, moist disturbed areas
Animals affected: cattle, sheep, horses

Poa pratensis L.
Common name: Kentucky bluegrass
Toxin: ergot infestation of seed heads
Habitat: lawns, pastures, meadows
Animals affected: cattle, sheep, horses

Secale cereale L.
Common name: rye
Toxin: ergot infestation of seed heads
Habitat: cultivated
Animals affected: cattle, sheep, horses, humans

Setaria lutescens (Wiegel) Hubb.
Common name: yellow bristlegrass
Toxin: mechanically injurious (rare)
Habitat: waste areas
Animals affected: cattle

Sorghum bicolor (L.) Moench
Common name: common sorghum, milo
Toxin: cyanide
Habitat: waste areas, cultivated
Animals affected: cattle, sheep, horses

*Sorghum halepense (L.) Pers.
Common name: Johnsongrass
Toxin: cynanide
Habitat: waste areas, cultivated fields
Animals affected: cattle, sheep, horses

Stipa comata Trin. Rupr.
Common name: needle-and-thread
Toxin: mechanical injury from mature awns
Habitat: open slopes
Animals affected: cattle, sheep, horses

Stipa neomexicana (Thurb.) Scribn.
Common name: New Mexico feathergrass
Toxin: mechanical injury from mature awns
Habitat: dry hills
Animals affected: cattle, sheep, horses

Stipa robusta (Vasey) Scribn.
Common name: sleepygrass
Toxin: unknown narcotic
Habitat: open slopes, northern to south-central New Mexico
Animals affected: horses

Zea mays L.
Common name: common maize
Toxin: nitrates
Habitat: cultivated
Animals affected: cattle

Polygalaceae

Polygala sanguinea (L.) Farwell
Common name: milkwort, snakeroot
Toxin: irritant drug
Habitat: plains
Animals affected: horses

Polygonaceae

Beta vulgaris L.
Common name: beet, sugar beet
Toxin: oxalates, nitrates
Habitat: cultivated
Animals affected: cattle

Fagopyrum sagittatum Gilib.
Common name: buckwheat
Toxin: primary photosensitizer
Habitat: waste areas, roadsides
Animals affected: cattle, sheep, horses, goats, swine, fowl

Rheum rhaponticum L.
Common name: rhubarb
Toxin: oxalic acid in the leaf blades
Habitat: cultivated
Animals affected: cattle, sheep

Rumex acetosella L.
Common name: sheep sorrel, dock
Toxin: oxalates in the leaf blades
Habitat: disturbed places
Animals affected: sheep

Rumex crispus L.
Common name: curlyleaf doc
Toxin: oxalates
Habitat: cultivated fields, waste areas
Animals affected: sheep

Polypodiaceae

*Pteridium aquilinum (L.) Kuhn.
Common name: bracken fern
Toxin: thiaminase
Habitat: open woods and clearings in the mountains
Animals affected: cattle, sheep, horses

Portulacaceae

Portulaca oleracea L.
Common name: common purslane
Toxin: oxalates
Habitat: waste areas, cultivated areas
Animals affected: sheep

Primulaceae

Anagallis arvensis L.
Common name: pimpernel
Toxin: unknown
Habitat: waste areas
Animals affected: sheep

Ranunculaceae

*Aconitum columbianum Nutt.
Common name: monkshood
Toxin: alkaloids
Habitat: moist ground, often along streams
Animals affected: cattle, sheep, horses

Actea arguta Nutt.
Common name: baneberry
Toxin: irritant oil
Habitat: woods
Animals affected: cattle, sheep, horses, humans

Anemone patens L.
Common name: pasque flower
Toxin: glycoside
Habitat: open meadows
Animals affected: sheep

Caltha leptosepala DC.
Common name: elkslip, march marigold
Toxin: glycoside
Habitat: wet meadows, boggy ground
Animals affected: cattle, sheep

*Delphinium barbeyi Huth.
Common name: Barbey larkspur, tall larkspur
Toxin: alkaloids
Habitat: open meadows
Animals affected: cattle, occasionally sheep

*Delphinium nelsonii Greene
Common name: Nelson larkspur
Toxin: alkaloids
Habitat: dry plains
Animals affected: cattle, sheep, horses

*Delphinium occidentale Wats.
Common name: larkspur
Toxin: alkaloids
Habitat: dry slopes in oak scrub
Animals affected: cattle, sheep, horses

*Delphinium robustum Rydb.
Common name: larkspur
Toxin: alkaloids
Habitat: mountain meadows
Animals affected: cattle, sheep, horses

*Delphinium vireseens Nutt.
Common name: larkspur
Toxin: alkaloids
Habitat: dry plains and hills
Animals affected: cattle, sheep, horses

Ranunculus aeris L.
Common name: tall buttercup
Toxin: glycoside
Habitat: open areas
Animals affected: cattle, sheep, horses

Ranunculus cymbalaria Purch
Common name: alkali buttercup, trailing buttercup
Toxin: glycoside
Habitat: wet ground
Animals affected: cattle, sheep, horses

Ranunculus scleratus L.
Common name: crowfoot, buttercup
Toxin: glycoside
Habitat: marshy ground
Animals affected: cattle, sheep, horses

Rosaceae

*Cereocarpus montanus Raf.
Common name: mountain mahogany
Toxin: cyanogenetic glycosides
Habitat: dry hillsides
Animals affected: cattle

Malus sylvestris Mill.
Common name: apple
Toxin: cyanide in leaves
Habitat: cultivated
Animals affected: cattle, horses, mules

Prunus armeniaea L.
Common name: apricot
Toxin: cyanogenetic glycoside, especially in seeds (pits)
Habitat: cultivated
Animals affected: cattle, sheep, horses

Prunus persiea Batsch
Common name: peach
Toxin: cyanogenetic glycoside, especially in seeds (pits)
Habitat: cultivated
Animals affected: cattle, sheep, horses

*Prunus serotina Ehrh.
Common name: southwestern chokecherry
Toxin: cyanogenetic glycoside
Habitat: along streams
Animals affected: cattle, sheep, horses

*Prunus virginiana L.
Common name: chokecherry
Toxin: cyanogenetic glycoside
Habitat: moist canyons and slopes
Animals affected: cattle, sheep

Santalaceae

Comandra umbellata (L.) Nutt.
Common name: bastard toadflax
Toxin: alkaloids, glycosides, selenium
Habitat: plains and forested slopes; parasitic on other plants
Animals affected: cattle, sheep, horses

Scrophulariaceae

Castilleja spp.
Common name: paintbrushes
Toxin: selenium
Habitat: foothills and plains
Animals affected: cattle

Sinopteridaceae

Dryopteris filix-mas (L.) Schott
Common name: malefern
Toxin: thiaminase
Habitat: damp, rocky places, often along streams
Animals affected: horses

*Notholana sinuata (Lag.) Kaulf. var. cochisenis (Goodding) Weath.
Common name: Jimmy fern, cloak fern
Toxin: unknown, passed through the milk
Habitat: dry, rocky areas, along canyon walls
Animals affected: sheep

Solanaceae

*Datura stramonium L.
Common name: Jimsonweed
Toxin: alkaloids
Habitat: waste or cultivated ground
Animals affected: cattle, sheep, horses, swine, mules, chickens, humans

*Datura wrightii Regel.
Common name: datura, thornapple
Toxin: alkaloids
Habitat: mesas and waste grounds
Animals affected: cattle, sheep, horses, swine, mules, chickens, humans

Hyoscyamus niger L.
Common name: henbane
Toxin: alkaloids
Habitat: moist roadsides
Animals affected: cattle, sheep, fowl

Lycium halimifolium Mill.
Common name: matrimony vine
Toxin: unknown
Habitat: dry hills and plains
Animals affected: calves, sheep

Lycopersicon esculentum Mill.
Common name: tomato
Toxin: alkaloids in leaves and vines
Habitat: cultivated
Animals affected: cattle, swine

Nicotiana attenuata S. Wats.
Common name: coyote tobacco
Toxin: nicotine
Habitat: sandy ground near streams and washes
Animals affected: cattle, sheep, horses, swine

Nicotiana giauca Graham
Common name: tree tobacco
Toxin: nicotine
Habitat: along desert streams and washes
Animals affected: cattle, sheep, horses

Nicotiana trigonophylla Dunal
Common name: desert tobacco
Toxin: nicotine
Habitat: desert canyons, washes
Animals affected: cattle, sheep, horses

Physalis virginiana Mill. var. sonora (Torr.) Waterfall
Common name: groundcherry
Toxin: unknown
Habitat: moist ground, widespread
Animals affected: sheep

*Solanum elaeagnifolium Cav.
Common name: silverleaf nightshade, horsenettle
Toxin: glycoalkaloids
Habitat: shaded slopes or waste areas
Animals affected: cattle, sheep

Solanum nigrum L.
Common name: black nightshade
Toxin: glycoalkaloids
Habitat: shaded slopes or waste areas
Animals affected: cattle, sheep, horses

Solanum rostratum Dunal.
Common name: buffalobur
Toxin: glycoalkaloids
Habitat: plains and waste areas
Animals affected: cattle, swine

Solanum triflorum Nutt.
Common name: cutleaf nightshade
Toxin: glycoalkaloids
Habitat: plains, roadsides, streambeds
Animals affected: cattle, horses

Solanum sarachoides Sendt.
Common name: hairy nightshade
Toxin: glycoalkaloids
Habitat: waste areas
Animals affected: cattle, sheep, horses

Typhaceae

Typha latifolia L.
Common name: cattail
Toxin: hayfever
Habitat: marshes, ponds
Animals affected: horses

Urtica gracilis Ait.
Common name: stinging nettle
Toxin: stinging hairs cause dematitis, nitrates
Habitat: rich damp soil in thickets in mountains
Animals affected: horses

Verbenaceae

Aloysia wrightii (Gray) Heller
Common name: whitebrush
Toxin: unknown
Habitat: dry, rocky slopes, often on limestone soils
Animals affected: horses

Zygophyllaceae

Kallstroemia hirsutissima Vail
Common name: hairy caltrop
Toxin: unknown
Habitat: dry plains, widespread
Animals affected: cattle, sheep, goats

Peganum harmala L.
Common name: African rue
Toxin: alkaloids
Habitat: southern dry plains
Animals affected: cattle

*Tribulus terrestris L.
Common name: puncturevine, goathead
Toxin: nitrates, photosensitizing compound, saponins
Habitat: disturbed areas
Animals affected: sheep

References

Fuller, T. C., & McClintock, E. (1986). Poisonous Plants of California. Berkely, CA: University of California Press.

James, L. F., Keeler, R. F., Johnson, A. E., Williams, M. C., Cronin, E. H., & Olsen, J. D. (1980). Plants poisonous to livestock in the western states (Inf. Bul. 415). Washington, D.C.: US Department of Agriculture.

Kingsbury, J. M. (1964). Poisonous plants of the United States and Canada. Upper Saddle River, NJ: Prentice-Hall, Inc.

Norris, J. J., & Valentine, K. A. (1957). Principle Livestock-Poisoning Plants of New Mexico Ranges (Circular 274). Las Cruces, NM: Cooperative Extension Service.

Schmutz, E. M., Freeman, B. N., & Reed, R. E. (1968). Livestock-Poisoning Plants of Arizona. Tucson, AZ: University of Arizona Press.

Original Author(s): Kelly W. Allred. Professor, Department of Animal and Range Sciences, New Mexico State University, Las Cruces. Published February 2010.

Casey Spackman is an Assistant Professor and Extension Range Management Specialist at New Mexico State University. He earned his Ph.D. at Utah State University. His Extension efforts aim to assist producers, land managers, and agency personnel in monitoring and developing management objectives that maintain or improve natural resource health and sustainability.  

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Reviewed December 2024. Las Cruces, NM.