Pteridium esculentum

Pteridium esculentum
Bracken at Chatswood West, Australia
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Pteridopsida
Order:	Dennstaedtiales
Family:	Dennstaedtiaceae
Genus:	Pteridium
Species:	P. esculentum
Binomial name
Pteridium esculentum (G.Forst.) Cockayne

Pteridium esculentum, commonly known as 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,^[1] it gained its current binomial name in 1908.^[2] The Eora people of the Sydney region knew it as gurgi.^[3]

P. esculentum grows from creeping rhizomes, which are covered with reddish hair. From them arise single large roughly triangular fronds, which grow to 0.5–2 metres (1 ft 8 in–6 ft 7 in) tall. The fronds are stiff with a brown stripe.^[4]

It is found in all states of Australia apart from the Northern Territory, as well as New Zealand, Norfolk Island, Malaysia, Polynesia, and New Caledonia. Within Victoria it is widespread and common to altitudes of 1,000 metres (3,300 ft).^[5] In New South Wales, it occurs in across central, eastern and southern parts of the state. It can also be weedy and invade disturbed areas.^[4] In Australia, it grows near the southern and western coastlines, as far north as Geraldton.^[6]

Like its northern hemisphere relatives, Pteridium esculentum is very quick to colonise disturbed areas and can outcompete other plants to form a dense understorey. It is often treated as a weed. It does create a more humid sheltered microclimate under its leaves and is food for a variety of native insects.^[7] Two species of fruit fly (Drosophila) were recorded in a field study near Sydney,^[8] Another study near Sydney yielded 17 herbivorous arthropods (15 insects and two mites), notable for the lack of Hymenoptera (ants, bees and wasps) and Coleoptera (beetles).^[9]

Bracken fronds in New Zealand

Uses

The Māori of New Zealand used the rhizomes of P. esculentum (aruhe) as a staple food, especially for exploring or hunting groups away from permanent settlements; much of the widespread distribution of this species in present-day New Zealand is in fact a consequence of prehistoric deforestation and subsequent tending of aruhe stands on rich soils (which produced the best rhizomes).^[10] The rhizomes were air-dried so that they could be stored and became lighter; for consumption, they were briefly heated and then softened with a patu aruhe (rhizome pounder); the starch could then be sucked from the fibers by each diner, or collected if it were to be prepared for a larger feast. Patu aruhe were significant items and several distinct styles were developed.^[10]

Aborigines in Australia ate the roots after they were pounded into a paste and roasted.^[3]

Pteridium esculentum contains the known bracken carcinogen ptaquiloside.^[11] Concentrations of ptaquiloside in bracken in New Zealand vary greatly, and in a high proportion of stands ptaquiloside is not found. A higher incidence of ptaquiloside, and some very high concentrations, are found in areas where bovine enzootic haematuria and/or acute haemorrhagic syndrome was known to occur.^[12]

References