Hazardous Plants

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Hazardous Plants

A basic list of the Hazardous Plants important to our ancestors in the Old West.
Additions may be expected from time to time… Doc

Cocklebur Xanthium strumarium - Hazardous PlantsCocklebur (Xanthium strumarium) Aka: clotbur, rough cocklebur, large cocklebur, common cocklebur. Covered with stiff, hooked spines, which stick to fur and clothing, it can be extremely difficult to remove. Burs (seeds) are carried long distances from the parent plant with the help of humans and animals. In flower, typically from July to October. The seedlings and seeds of common cockleburs are highly toxic to mammalian herbivores, including cattle, horses, sheep, and pigs. The foliage of more mature plants is less toxic, although the fatal poisoning of calves has been reported. When cattle and horses feed on mature plants with burry fruits and flowers, this can cause obstruction of the gastrointestinal tract if they are eaten in sufficient quantity. Photo: U.S. PD 2005, USDA Robert H. Mohlenbrock.  {001}
also at:
The Originals – Resources & Hazards – Plants – Food PlantsCocklebur
The Originals – Resources & Hazards – Plants – Functional PlantsCocklebur
The Originals – Resources & Hazards – Plants – Medicinal Plants. – Cocklebur


Amanita verna - Hazardous PlantsDestroying Angel (Aminita Verna) “One lick, ecstasy; two licks, death!” Not quite, but a single bite might well be your last. The toxin is alpha-amanitin which will produce complete liver and perhaps kidney failure.You can bet the Medicine Men knew about this beautiful white mushroom; as did anyone else who collected edible mushrooms. If you aren’t sure, you had best slice your puffballs and be sure there is no ring or cup in there; immature, unreleased aminita fruiting bodies might fool a careless collector, once. It’s out there and it has some equally nasty relatives. Admire, photograph and leave be. Photo: U.S. PD 2007, Pieria  {001}


Jimson Weed Datura stramonium - Hazardous Plants

Jimson Weed (Datura stramonium) Toxic to cattle and other range animals. Sometimes called “loco weed” but this is not the main player*. Photo: U.S. PD 2005, Tabor {001}
see also:
*Locoweed – below)
The Originals – Resources & Hazards – Plants
Hallucinogenic PlantsJimson Weed


Tall Larkspur - Hazardous Plants

Tall Larkspur

Larkspur (Delphinium sp.) Some 300 species, all toxic to man and beast. A true problem plant in the west. Tall larkspur (Delphinium barbeyi), in particular, is a significant cause of cattle poisoning on rangelands in the western United States. Ranchers often delay moving cattle onto high-elevation ranges until late summer when the toxicity of these plants is somewhat reduced. Any part of this plant is toxic to humans, especially the younger parts. Skin irritation and severe digestive discomfort will soon follow ingestion; a cocktail of alkaloids can produce heart failure and various unhealthy paralyses; death can occur within a few hours. Photo: U.S. PD, Dave Powell, USDA Forest Service    {001}


Leafy Spurge Quarntine Sign - Idaho - Hazardous Plants

Quarantine Sign

Leafy Spurge (Euphorbia virgata), aka: Wolf’s Milk, is a species of spurge native to Europe and Asia, naturalized in North America, where it is an invasive species. Commonly confused with Euphorbia esula. Transported to the United States possibly as a seed impurity in the early 19th century, it has been found in 458 counties in 26 states and occurs across much of the northern U.S., with the most extensive infestations reported for Montana, North Dakota, Nebraska, South Dakota, and Wyoming. These plants contain a poisonous, milky, white, latex-like sap, toxic to cattle and horses but not to goats and sheep which have been employed in some areas attempting to control this most difficult weed. An aggressive invader, once present it can completely overtake large areas of open land, displacing native vegetation in prairie habitats and fields via shading, usurping the available water and nutrients and through plant toxins that prevent the growth of other plants underneath it. Leafy spurge quickly colonizes areas with bare soil, especially those caused by human disturbance where native species are removed. The common name “spurge” derives from the Middle English/Old French espurge (“to purge”), due to the use of the plant’s sap as a purgative in Europe. Photos: U.S. PD – LH: 2014 by Famartin, Leafy Spurge Quarantine Area sign along Goose Creek Road where it crosses from Box Elder County, Utah into Cassia County, ID. RH: 2014 by Hermann Schachner Leafy Spurge (Euphorbia virgata).  {001}


Locoweed Oxytropis Sericea - Hazardous Plants

White Locoweed
(Oxytropis sericea)

Locoweed Oxytropis Lambertii - Hazardous Plants

Purple Locoweed
(Oxytropis lambertii)

Loco Weed Common species include: White Locoweed (Oxytropis sericea) aka: white point locoweed; Purple Locoweed (Oxytropis lambertii) aka: Lambert locoweed, woolly loco; and others. All plant parts are toxic, at all stages of growth, and dangerous throughout the year, even when they have matured and dried. The toxin is swainsonine although some plants which concentrate high levels of selenium generate similar symptoms. Locoweed is found on foothills and semiarid regions. It grows in tufts or clumps, 8 to 30 cm high. Locoweed flowers resemble sweet peas. Blossoms may be blue, purple, yellow, or white. It is the most widespread poisonous plant problem in the western United States.
locoweed Map - Hazardous PlantsCattle, goats, horses, sheep and wildlife (deer, elk and pronghorn) are all affected by eating locoweed. Signs of poisoning appear after 2 to 3 weeks of continuous grazing on the plant. There are four principal effects on livestock: (1) neurological damage (particularly with horses); (2) emaciation; (3) abortions, birth defects, increased neonatal death (cattle, goats & sheep); and (4) congestive right heart failure (cattle) when grazed at high elevations.
Animals with chronic locoweed poisoning become emaciated and wasted as they lose the ability to find and utilize feed. Some may die of starvation but most will die from misadventure. No treatments have been identified that are effective in reversing or minimizing locoweed poisoning. Photos: U.S. P.D. – LH – Oxytropis sericea, CSU; RH – Oxytropis lambertii, OPSU;  Map: U.S. P.D. Locoweed occurrence in the U.S.  {001}


Poison Ivy Toxicodendron radicans - Hazardous PlantsPoison Ivy (Toxicodendron radicans) Chemical warfare with a clear liquid in the sap of the plant, Urushiol-induced contact dermatitis will cause a rash, burning or itching and lasting discomfort to most who touch it. When burned, inhalation of the smoke may cause the rash to appear on the lining of the lungs (pulmonary edema), causing extreme pain and possibly fatal respiratory problems. Photo: U.S. PD 2005, Esculapio  {001}


PoisonOak - Hazardous PlantsPoison Oak (Toxicodendron diversilobum) aka: Pacific Poison Oak; Western Poison Oak. Same game as the Poison Ivy; Urushiol-induced contact dermatitis. The smoke from burning these toxic plants is particularly dangerous, land clearing or wildfires can be serious hazards. Photo: U.S. PD 2004, Elf.  {001}
also at:
The Originals – Resources & Hazards – Plants – Functional PlantsPoison Oak
The Originals – Resources & Hazards – Plants – Medicinal PlantsPoison Oak


Poison Sumac Toxicodendron vernix - Hazardous PlantsPoison Sumac (Toxicodendron vernix) This plant used to be in the Rhus family but is not too closely related to the other sumacs. Without its berries [white], it can be confused with staghorn sumac (Rhus typhina)) [red berries], an unfortunate error. The same toxin as Poison Ivy & Poison Oak generating Urushiol-induced contact dermatitis. Same hazards when burned as the others. More dangerous than either of it’s relatives; some botanists contend that poison sumac is the most toxic plant species in the United States. Photo: U.S. PD 2005, USDA  {001}


Tumbleweeds on a fence line. - Hazardous PlantsTumbleweed (genus Salsola) According to UTAH State University it’s actually a Russian invader; native to the Ural Mountain steppe. Seeds of several closely related tumbleweed plants in the genus Salsola first arrived in the United States in flaxseed shipments brought by Russian immigrants to South Dakota (early 1870’s). The plants took to the high-and-dry environment of the Plains states and quickly spread across the West. Today, it is inextricably linked culturally with the American West. Sometimes known as Russian thistle. Not particularly hazardous, but it can blow up against fence lines, buildings and machinery on pose a fire hazard (but not an ignition source). It’s mostly just a pain when it piles up in the way. Photo: U.S. PD? internet Tumbleweeds on a fence.  {001}

for related information on this subject in Old West Daily Reader
see also:
The Originals Index- Resources & Hazards – Plants – Food Plants
The Originals Index – Resources & Hazards – Plants – Functional Plants
The Originals Index – Resources & Hazards – Plants – Medicinal Plants
The Originals Index – Resources & Hazards – Plants – Hallucinogenic Plants
The Originals Index – Resources & Hazards – Animals

barbed wire divider2 - Hazardous PlantsEnd Page: Hazardous Plants

{001} C 01/20; E 08/18: F 07/14; P 10/17

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