PTERIDIUM AQUILINUM

FernThe ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns. They produce coiled fiddleheads that uncoil and expand into fronds. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida, comprising both the leptosporangiate (Polypodiidae) and eusporangiate ferns, the latter group including horsetails, whisk ferns, marattioid ferns, and ophioglossoid ferns. The fern crown group, consisting of the leptosporangiates and eusporangiates, is estimated to have originated in the late Silurian period 423.2 million years ago, but Polypodiales, the group that makes up 80% of living fern diversity, did not appear and diversify until the Cretaceous, contemporaneous with the rise of flowering plants that came to dominate the world's flora. Ferns are not of major economic importance, but some are used for food, medicine, as biofertilizer, as ornamental plants, and for remediating contaminated soil. They have been the subject of research for their ability to remove some chemical pollutants from the atmosphere. Some fern species, such as bracken (Pteridium aquilinum) and water fern (Azolla filiculoides), are significant weeds worldwide. Some fern genera, such as Azolla, can fix nitrogen and make a significant input to the nitrogen nutrition of rice paddies. They also play certain roles in folklore.

Fern

BrackenBracken (Pteridium) is a genus of large, coarse ferns in the family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that undergo alternation of generations, having both large plants that produce spores and small plants that produce sex cells (eggs and sperm) in its life cycle. Brackens are noted for their large, highly divided leaves. They are found on all continents except Antarctica and in all environments except deserts, though their typical habitat is moorland. The genus probably has the widest distribution of any fern in the world. The word bracken is of Old Norse origin, related to Swedish bräken and Danish bregne, both meaning fern. In the past, the genus was commonly treated as having only one species, Pteridium aquilinum, but the recent trend is to subdivide it into about ten species. Like other ferns, brackens do not have seeds or fruits, but the immature fronds, known as fiddleheads, are sometimes eaten, although some are thought to be carcinogenic.

Bracken

FiddleheadFiddleheads or fiddlehead greens are the furled fronds from a fledgling fern, harvested for use as a vegetable. Left on the plant, each fiddlehead would unroll into a new frond (circinate vernation). As fiddleheads are harvested early in the season, before the frond has opened and reached its full height, they are cut fairly close to the ground. Fiddleheads from brackens contain ptaquiloside, a compound associated with bracken toxicity, and thiaminase. Not all species contain ptaquiloside, such as Diplazium esculentum, a fern with fiddleheads regularly consumed in parts of East Asia, which differs from bracken (Pteridium aquilinum). The fiddlehead resembles the curled ornamentation (called a scroll) on the end of a stringed instrument, such as a fiddle. It is also called a crozier, after the curved staff used by bishops, which has its origins in the shepherd's crook.

Fiddlehead

Pteridium aquilinumPteridium aquilinum, commonly called bracken, brake, pasture brake, common bracken, and also known as eagle fern, is a species of fern occurring in temperate and subtropical regions in both hemispheres. Originally native to Eurasia and North America, the extreme lightness of its spores has led to it achieving a cosmopolitan distribution.

Pteridium

aquilinum

PtaquilosidePtaquiloside is a norsesquiterpene glucoside produced by bracken ferns (majorly Pteridium aquilinum) during metabolism. It is identified to be the main carcinogen of the ferns and to be responsible for their biological effects, such as haemorrhagic disease and bright blindness in livestock and oesophageal, gastric cancer in humans. Ptaquiloside has an unstable chemical structure and acts as a DNA alkylating agent under physiological conditions. It was first isolated and characterized by Yamada and co-workers in 1983. The pure form ptaquiloside is a colorless amorphous compound. It is readily soluble in water and fairly soluble in ethyl acetate. Except in the plants, ptaquiloside has been detected in the milk and meat of affected livestock, as well as in the underground water and dry soil around bracken fern vegetation. The prevalence of ptaquiloside in daily sources along with its carcinogenic effects make it an increasing biological hazard in modern days.

Ptaquiloside

Pteridium esculentumPteridium esculentum, commonly known as bracken fern, Austral bracken or simply bracken, is a species of the bracken genus native to a number of countries in the Southern Hemisphere. Esculentum means edible. First described as Pteris esculenta by German botanist Georg Forster in 1786, it gained its current binomial name in 1908. The rhizome of the plant was a staple in traditional Māori diets in New Zealand and was eaten by Indigenous Australians, it is now known to contain the carcinogen ptaquiloside.

Pteridium

esculentum