About Pteridium aquilinum subsp. feei (W.Schaffn. ex Fée) J.A.Thomson, Mickel & Mehltr.
Pteridium aquilinum subsp. feei, commonly called common bracken, is a deciduous herbaceous perennial plant. It produces large, roughly triangular fronds singly that grow upward from an underground rhizome, reaching 0.3–1 metre (1–3+1⁄2 feet) in height. The main stem, or stipe, grows up to 1 centimetre (1⁄2 inch) in diameter at its base. The plant dies back to ground level each autumn. The underground rhizome can grow up to 3.5 metres (11+1⁄2 ft) deep, about 5 cm (2 in) in diameter, and up to 15 m (50 ft) long. Because it regrows each spring from this underground rhizome, Pteridium aquilinum typically forms dense colonies of genetically identical fronds. These colonies can be up to 650 years old, with individual rhizomes living up to 72 years. One colony studied by Eino Oinonen in Raakkyla, North Karelia, Finland, measured 489 m (1,604 ft) in diameter and was estimated to be over 1400 years old based on its growth rate. At the start of the spring growing cycle, the rhizome first sends up fiddleheads. A single rhizome’s density and covered area maximize its biological success when producing new growth. New growth appears as vertical coiled stalks covered in silver-grey hairs, which can reach a metre or more in height before unfurling into mature fronds. Bracken is native to Europe, Eastern Asia and North America, and now has an almost cosmopolitan distribution. In the Americas, it occurs throughout the continental United States and the Canadian provinces of Ontario, Quebec, and Newfoundland. The northern edge of its range extends to southern Alaska, while its southern extent reaches northern portions of Mexico, as well as the Greater Antilles in the Caribbean. It grows as a weed in acidic upland pastures of northwestern Europe. It grows in pastures, deciduous and coniferous woodlands, and hillsides, and prefers acidic soils. It is an adaptable plant that readily colonizes disturbed areas. It can be aggressive even in its native countries; for example, in England it has invaded heather (Calluna vulgaris (L.) Hull) stands on the North Yorkshire moors. In Ireland, it is found in open woodland and sandy pastures. Reproduction occurs via sporangia that form in sori on the underside of fronds. The sori are arranged in narrow brown bands, and spores are produced over July, August and September. Common bracken contains the carcinogenic compound ptaquiloside. Ptaquiloside is known to cause haemorrhagic diseases in ruminants, and tumours plus haematological problems in non-ruminants, and it is correlated with oesophageal and gastric cancer in humans. Chronic consumption of bracken is also associated with upper digestive tract (UDT) squamous cell carcinomas in cattle (a type of ruminant), with the most aggressive and serious tumours located in the caudal (lower) UDT. High rates of stomach cancer occur in Japan and North Wales, where young bracken stems are used as a vegetable, but it is unknown whether bracken contributes to this cancer, or if the cancer can be attributed to another cause. Consumption of ptaquiloside-contaminated milk is thought to contribute to human gastric cancer in the Andean states of Venezuela. Bracken spores have also been implicated as carcinogens. Consumption of contaminated water and meat may also be dangerous. However, ptaquiloside is water-soluble, and its levels are reduced by soaking bracken in cool water. Korean and Japanese cooks have traditionally soaked bracken shoots in water and ash to detoxify the plant before eating. Ptaquiloside also degenerates at room temperature, which explains why rat studies of the toxin used toxin stored at −20 °C (−4 °F). At boiling temperature, the carcinogen denatures almost completely. Salt and baking soda also help volatilize the chemical. Selenium supplementation has been suggested to both prevent and reverse the immunotoxic effects induced by ptaquiloside from Pteridium aquilinum. Despite its confirmed toxicity, Pteridium aquilinum is the fifth most widely distributed common weed species in the world, and it has a long history of human consumption across many parts of the globe. Its toxicity and wide distribution have led to varied cultural attitudes toward consumption of the plant. In the United Kingdom, where Pteridium aquilinum grows very successfully, the rhizome was consumed during and after World War I. However, the Royal Horticultural Society now explicitly advises against consuming the plant due to its toxicity. Bracken is a widely eaten vegetable in Korea, Japan, the Russian Far East, and parts of China, where it has historically been one of the most important consumed wild vegetables. After immigrating, populations from these countries that traditionally consume bracken can still access it in new locations due to Pteridium aquilinum’s global ubiquity. In Korea, bracken is known as gosari. It is soaked, parboiled, and stir-fried, and often eaten as a side dish called namul. It is also a classic ingredient in bibimbap. In Japan, bracken is known as warabi (蕨, ワラビ), and a jelly-like starch made from it is a key ingredient in the chilled dessert warabimochi. As a type of sansai (mountain vegetable), young bracken shoots are steamed, boiled, or cooked in soups. Shoots are also preserved in salt, sake, or miso. Bracken shoots have been used to produce beer in Siberia, and among indigenous peoples of North America. The rhizome can be ground into flour to make bread. In the Canary Islands, the rhizome was historically used to make a porridge called gofio. In the Mediterranean region, bracken leaves are used to filter sheep’s milk, and to store freshly made ricotta cheese. The name Nooksack translates to "always bracken fern place" in the Nooksack language, and the rhizome of this plant was eaten extensively by the Nooksack people and other tribes of the Pacific Northwest. Young bracken fronds can be harvested easily and should be cooked for 30 to 60 minutes. Mature bracken is toxic due to thiaminase, a compound that can be destroyed by cooking. Bracken should be avoided if you do not have enough skill to prepare it properly. In Finnish traditional medicine, bracken has been used as a remedy in multiple ways. Elias Lönnrot advised using a powder made from the plant’s roots to drive away maggots. A decoction made from bracken was used to treat stomach problems, gout and joint pain. Bracken leaves were used as filling in mattresses, because it was believed to lessen rheumatic pain and drive away vermin.
