Scientific name: Pteridium aquilinum (L.) Kuhn
Common name: Brackenfern
Description: This cosmopolitan perennial fern starts the growth of its fronds in June, and they remain green until early October. The fronds reach a height of 2 to 4 feet and develop from deep underground stems. The blades of the fronds are broadly triangular in outline and two to three times pinnate. The mature fronds bear thousands of spore-bearing capsules (sporangia) on the lower leaf margins. The leaf margin recurves downward to protect the delicate sporangia.
Occurrence: This species is found frequently from Virginia and Tennessee west to the Pacific in the middle and upper mountain zone, and is found generally in subacid soil In moist forest clearings. It also occurs in burned-over sites in forests where there is some shade.
Toxicity: Brackenfern contains a carcinogen that may cause cancer. Although humans do not normally eat brackenfern, the carcinogen may occur in the milk of cows that have fed on the plant. Bladder and intestinal cancer has been produced experimentally in cows fed brackenfern and in animals that subsequently drank milk from these cows.
Symptoms: No symptoms of direct poisoning in humans are recorded. The high incidence of bladder and intestinal cancer among humans in WaIes, where brackenfern is common in grazing lands, may be related to contaminated milk.