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Pteridium aquilinum Minimize
BRACKEN FERN -  Pteridium aquilinum
BRACKEN FERN -  Pteridium aquilinum
BRACKEN FERN -  Pteridium aquilinum
BRACKEN FERN -  Pteridium aquilinum
BRACKEN FERN -  Pteridium aquilinum

Pteridium aquilinum

BRACKEN FERN

Distinguishing features
Native perennial herb with black horizontal rhizomes deep in the soil (often below plow depth), by means of which it spreads and forms large patches; leaves 3-4 feet tall in good sites; leaf stalk forks into three main parts, producing a triangular, bipinnately pinnatifid blade; spores produced in late summer in sporangia protected by the rolled-under edges of the blade.
Description
Deciduous fern with a horizontal root system that can grow up to several meters long.
Geographic range
Found throughout the United States in dry open woodlands. Spreads rapidly due to its extensive root system.
Toxic principle
Thiaminase splits the essential vitamin thiamine (B1) into its two inactive components, pyrimidine and thiazole, causing thiamine deficiency.
Toxicity
Bracken fern is associated with poisoning of cattle, sheep, pigs, horses, and humans. Horses must consume a diet of 3-5% bracken fern for at least 30 days before clinical signs appear. Rhizomes are the most toxic portion of the plant.
Mechanism of toxicologic damage
Thiamine is essential in energy metabolism and is broken down by thiaminase. Thiamine deficiency causes CNS depression and polioencephalomalacia.
Diagnosis
Clinical signs
Depression, muscle tremors, uncoordinated gait. Retinal degeneration and blindness. Hemorrhaging and bone marrow destruction, urinary bladder cancer, and digestive tract cancers.
Laboratory Diagnosis
Severe anemia may be seen. Decreased thiamine levels and increased pyruvic acid levels are seen.
Treatment
Treat horses with 5 mg/kg body weight of thiamine intravenously. Repeat the dose intramuscularly for several days. Nursing care and systemic antibiotics are also helpful.
Prevention
Feed animals a balanced diet free of bracken fern.

Read more in the Poisonous Plants of Pennsylvania Publication

Effect on Animals Minimize
Cow with hemorrhage into muscle seconday to aplastic anemia.

Cow with hemorrhage into muscle seconday to aplastic anemia.
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