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Which pine trees are poisonous?

Updated February 21, 2017

A pine tree is a variety of conifer, which is characterised by being able to produce cones and having scale- or needle-like leaves. Young pine trees tend to grow in cone shapes (which individuals commonly harvest for Christmas trees), while older pines will eventually lose their lower branches, and tend to have flattops that fan outward. And while pines are most commonly associated with lumber, holidays and their distinctive scent, all pines carry with them some poisonous attributes.

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All Pines Are Poisonous

All pine trees produce needles, and all of these needles, according to the New Zealand Tree Crops Association, are poisonous if ingested in large enough amounts. All pine needles, regardless of the specific tree species they come from, contain lignols, resins and mycotoxins, which can produce toxic reactions in animals, such as livestock. But certain species of pine tree are known for having particularly toxic needles.

Ponderosa Pine

The ponderosa pine (pinus ponderosa) is native to western North America, and is characterised by a distinctive orange bark. According to the U.S. Department of Agriculture, the needles of the ponderosa pine contain a unique toxin in addition to the other toxic compounds common to pines. This toxin is isocupressic acid, which is best known for causing pregnant livestock to have premature births or miscarriages. Other symptoms include excessive uterine hemorrhaging, a prolonged retaining of placenta, and endometritis, which is the inflammation of the mucous membranes that line the uterus. According to the Depart of Agriculture, the ponderosa's needles are toxic both when green and living, and when they are dried out and appear yellowish or brownish in colour. To protect your livestock from poisoning, keep them away from pine trees and needles that have fallen on the ground.

Lodgepole Pine

According to the Depart of Agriculture, the lodgepole pine (pinus contorta) is also known to produce needles that contain isocupressic acid. The tall, slender tree is known for its adaptability to different climates and is particularly well suited for growing in areas that have recently been disrupted by fire. Like the ponderosa, the loddgepole pine is native to western North America.

Monterey Pine

The Monterey pine (pinus radiata), also known as the insignis pine and the radiata pine, is another western Northern American pine that is particularly well adapted to growing in coastal environments (such as Monterey, California). According to the New Zealand Tree Crops Association, the tree's needles contain negligible amounts of isocupressic acid, but it may still be enough to cause toxic reactions in livestock if they ingest the needles.

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About the Author

Erik Devaney is a writing professional specializing in health and science topics. His work has been featured on various websites. Devaney attended McGill University, where he earned a Bachelor of Arts in humanistic studies.

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