attributed to cyanogenic glycosides. P. virgin- 
iana is considered a major poisonous species 
for all kinds of livestock in parts of the West 
(U.S.D.A., A.D. & P.R.D. 1964; Stoddart et al. 
1949). Its HCN content is particularly high in 
early spring. 
Irritant oils of glycoside origin are found in 
several genera of the Ranunculaceae family. 
Anemone patens and some species of Ranuncu- 
lus, which contain highly toxic “protoane- 
monin,” are at least suspected of causing some 
animal losses. 
The occasional poisonous properties of Meli- 
lotus alba and M. officinalis are attributed to 
the glycoside “coumarin.” This compound is 
closely related to that used in the rodenticide, 
“Warfarin.” Losses are generally restricted to 
cattle feeding on spoiled sweetclover in hay or 
silage; such spoilage converts the nontoxic cou- 
marin to highly toxic discoumarol. 
The saponic glycosides in Solanum spp., Ses- 
bania spp., Linum neomexicana, and Agro- 
stemma githago have occasionally poisoned 
livestock. Also, the saponins found in some 
legumes (i.e., Medicago satiro) are at least 
suspected of contributing to bloat in ruminants 
(Dougherty 1956). Saponin content varies 
with season, stage of growth, and plant part. 
Helenium hoopesi, a major poisonous plant 
found in the central Rocky Mountains, derives 
its toxicity from the glycoside, “Dugaldin.” 
Losses are usually restricted to sheep; how- 
ever, cattle have been poisoned experimentally. 
Alkaloids 
Alkaloids may be present in at least 5 per- 
cent of all plant species: most often they are 
found as soluble, organic acids. They are par- 
ticularly common in the Leguminosae and 
Amaryllidaceae families. More than 5,000 dif- 
ferent alkaloids have been identified. Most af- 
fect the animal’s nervous system. In contrast 
to glycosides, the alkaloid content in a plant 
does not vary much with stage of growth, cli- 
mate, and water availability, but it does differ 
appreciably in different species. Since alkaloids 
are usually distributed throughout the plant, 
every plant part may be considered poisonous 
to livestock. 
One of the most important poisonous genera 
on our western ranges is Delphinium spp. 
(Huffman and Couch 1942), which derives its 
toxicity from the alkaloid “Delphinine.” D. 
barbeyi, D. nelsonii, and D. tricorne often 
cause severe poisoning problems on cattle 
ranges. Some genera very poisonous to sheep 
also have alkaloids as their toxin; Lupinus 
spp. contain the alkaloid “Quinolizidine,” and 
Zigadenus spp. contain the alkaloid “Vera- 
tramine.” The malformation in lambs known 
as “monkey-face” is attributed to the Vera- 
tramine found in Veratrum californicum. Only 
64 
recently, researchers found that the congenital 
deformity in calves known as “crooked calf,” 
which occurs in many parts of the West, is 
caused by consumption of Lupinus caudatus 
and L. sericeus by the dam during gestation 
(Shupe et al. 1968). 
Oxalates 
Oxalates occur in plants in the form of solu- 
ble and insoluble acids and salts. The soluble 
oxalates of sodium and potassium are the pri- 
mary offenders. Although many plants contain 
small amounts of soluble oxalates, few have 
enough to be considered poisonous. Oxalate 
concentrations differ appreciably with both 
season and location. Usually they reach a max- 
imum in late summer and fall. 
Moderate amounts of oxalates appear to be 
readily eliminated by livestock; however, large 
concentrations can result in the precipitation 
of oxalate crystals in the kidneys and urinary 
tract. Both the amount and time of ingestion 
are important determinants of whether toxic 
levels will be reached in the blood. Also, pres- 
ence of other food in the stomach lessens the 
absorption rate and decreases the chance of 
poisoning. 
Halogeton glomeratus is perhaps the most 
well-known plant that owes its toxic properties 
to soluble oxalates, primarily in the form of so- 
dium salts. The same toxin in Sarcobatus ver- 
miculatus also has caused substantial losses of 
sheep under certain conditions. It is usually 
considered a good forage when eaten in moder- 
ate amounts along with other forage; however, 
when eaten in large amounts without other 
forage, especially in the fall, death can result. 
Resinoids 
Some of the most poisonous plants in the 
north temperate zone contain resinoids as their 
toxin. Resinoids are complex compounds that 
share a certain physical similarity despite hav- 
ing diverse chemical structures. The exact 
chemical structure is still unknown for most 
resinoids. Human beings as well as all kinds of 
livestock are sensitive to these toxins. 
Cicuta spp. is perhaps the best-known resi- 
noid plant. Both livestock and human beings 
have died from eating parts of this plant, par- 
ticularly the roots. They contain the resinoid 
“Cicutoxin,” which is characterized as a highly 
unsaturated higher alcohol. Cicutoxin acts di- 
rectly on the central nervous system, usually 
causing rapid death. Most cases of livestock 
poisoning from this species occur in the spring, 
when the new leaves are toxic and the ground 
is so soft that animals pull up and eat the roots 
along with the tops. 
Asclepias spp. are also highly poisonous resi- 
noid plants. The most toxic species, A. labri- 
formis, can cause death when as little as 0.05 
