PTERIDIUM AQUILINUM: CHARACTERISTICS, HABITAT, LIFE CYCLE, PROPERTIES - SCIENCE - 2024

Pteridium aquilinum is a perennial fern species that belongs to the Dennstaedtiaceae family. Known as amambáy, fern, eagle fern, common fern, female fern, pig fern, wild fern or jeleche, it is a species with wide distribution around the planet.

It is a herbaceous fern with a robust and thick rhizome with alternate fronds and petioles up to 2 m in length. The leaflets are made up of oblong terminal pinnae with a smooth upper surface and a pubescent underside; the sporangia are grouped in marginal sori and develop globular spores.

Pteridium aquilinum. Source: Ximenex / CC BY-SA 2.1 ES (https://creativecommons.org/licenses/by-sa/2.1/es/deed.en)

The spores are very small and light, which favors their dispersion over great distances through the wind, even between continents. It develops in a great variety of ecosystems and types of soils, it is also a dominant species that prevents the growth of other plants.

It is a rustic species that adapts to adverse conditions and lacks natural enemies due to the fact that it produces metabolites with a toxic effect. Its rhizome is very resistant to fire and has a dense growth, which is why in certain ecosystems it is classified as a weed.

It is considered a toxic plant, its spores present carcinogenic substances, so its presence is associated with cases of stomach cancer. In addition, the fronds contain thiaminase, an enzyme that destroys thiamine or vitamin B _{1 in} the body.

General characteristics

Appearances

Isospore fern with creeping growth, formed by thin underground rhizomes of brown color and covered with dark hairs, measuring between 50-100 cm in length. In general, it forms a dense bush with numerous fronds reaching 1-2 m in length, under certain conditions up to 4-5 m.

Leaves / fronds

The leaves, known as fronds or fronds, are megaphiles or large, flattened and vascularized leaves formed by oblong pinnae. Each frond, 1-4 m long, is tripinnate or tetrapinnate, smooth on the upper surface and hairy on the underside.

The fronds grow quite separate and have a petiole smaller or equal in size to the leaf blade. The petiole is straight, stiff and furrowed, with a broad and densely hairy base.

Sporangia / spores

On the underside of the fertile fronds, sori are formed, structures where sporangia that contain the spores develop. Sporangia are spheroidal structures with thickened cell walls. Sporulation occurs between June and October.

Trilet spores are the reproductive cells that contain the genetic material and allow the fern to reproduce. They are protected by a membrane known as indusios or are directly exposed to the outside.

Detail of the leaves of Pteridium aquilinum. Source: © Hans Hillewaert

Taxonomy

- Kingdom: Plantae

- Division: Pteridophyta

- Class: Pteridopsida

- Order: Pteridales

- Family: Dennstaedtiaceae

- Genus: Pteridium

- Species: Pteridium aquilinum (L.) Kuhn in Kersten (1879)

Etymology

- Pteridium: the name of the genus derives from the diminutive «pteris» which comes from the Greek «pteron» which means «wing», alluding to the shape of the fronds.

- aquilinum: the specific adjective in Latin means "like an eagle."

Infraspecific taxon

- Pteridium aquilinum subsp. aquilinum

- Pteridium aquilinum subsp. centrali-africanum Hieron. ex RE Fr.

- P. aquilinum subsp. decompositum (Gaud.) Lamoureux ex JA Thomson

- P. aquilinum subsp. fulvum CN Page

- Pteridium aquilinum var. pseudocaudatum Clute

- Pteridium aquilinum f. aquilinum

- P. aquilinum f. arachnoidea Hieron.

- P. aquilinum f. Fernald decipiens

- Pteridium aquilinum f. glabrata Hieron.

- Pteridium aquilinum f. longipes Senkozi & Akasawa

- P. aquilinum f. pubescens Hieron.

Shoots of Pteridium aquilinum. Source: © Marie-Lan Nguyen / Wikimedia Commons

Synonymy

- Pteridium japonicum Tardieu & C. Chr.

- Pteridium latiusculum (Desv.) Hieron. ex Fries

- Pteris aquilina L.

- Pteris aquilina Michx.

- P. aquilina f. glabrior Carruth.

- P. aquilina var. lanuginosa (Bory ex Willd.) Hook.

- Pteris capensis Thunb.

- Pteris lanuginosa Bory ex Willd.

Habitat and distribution

Its natural habitat is located in cool areas, forest clearings, grasslands, intervened land, abandoned crops, pastures or road margins. It is common in mesophilic forests, tropical forests, pine and oak forests, low deciduous forests, and high evergreen forests.

It is a fern that adapts to a wide variety of climates and soils, although it is susceptible to dry and freezing climates. It forms dense populations that completely cover the surface where it develops, and its rhizome is very resistant to forest fires.

It grows under shady forests, on various types of soils in their different stages of degradation, provided they are acidic. It prefers deep, loamy and sandy soils, well drained, slightly siliceous and with low saline content.

It is considered a cosmopolitan species that develops from sea level to 2,500-3,000 meters above sea level. However, it does not grow in the desert or xerophilic regions, nor in the polar, Arctic and Antarctic regions.

Biological cycle

The Pteridium aquilinum species is a perennial plant whose life cycle has two heteromorphic phases. The sporophytic phase, which is considered dominant, producing spores, and the gametophytic phase, where the gametes are produced.

To complete its life cycle, the eagle fern requires two generations of plants with different genetic endowments. One generation is diploid, the sporophytic, and the other haploid, the gametophytic.

The fern plant constitutes the diploid generation, each of the cells of the plant has two copies of chromosomes. In this phase known as sporophytic, the sporangia that contain the spores develop.

Once the spores germinate, a new sporophyte does not develop, but a new seedling develops. This generation is haploid and is known as a gametophyte, since it produces gametes in order to reproduce.

Fern life cycle. Source: Carl Axel Magnus Lindman / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Stages of the life cycle

- The cycle begins with the sporophyte or the fern plant as it is commonly known.

- The diploid chromosomal loaded sporophyte reproduces through haploid spores that are formed through meiosis.

- From each spore, by mitotic division, a haploid gametophyte is formed, with the same chromosomal load as the spore.

- The gametophyte develops male and female gametes. The ovules develop in the archegonia and the sperm in the antheridia.

- Humid environments favor the displacement of male gametes to fertilize the ovum.

- Once the ovum is fertilized, it remains attached to the gametophyte.

- The fusion of the genetic material of the male and female gametes form a diploid embryo.

- The embryo develops through mitosis to develop a new diploid sporophyte, thus completing the life cycle.

Pteridium aquilinum in its natural habitat. Source: Charlesblack / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Properties

Nutritional

Young fern fronds can be eaten as greens similar to asparagus. However, the presence of certain toxic substances requires prior cooking or a brine treatment for a long time.

With the dried and ground rhizomes, a low quality flour is produced to season certain traditional dishes. In some regions, the rhizomes are used as a substitute for hops and mixed with malt for artisanal brewing.

Handcrafted

In some regions, the dried fern is used to burn the skin of pigs after slaughter. In the same way, the fronds are used for the packaging, protection and transfer of various agricultural products.

Tannery

The rhizomes contain astringent elements or tannins. The decoction of the rhizomes is used to tan animal leather or buff.

Industrial

The ashes obtained from the burning of the entire plant are used as mineral fertilizer due to its high potassium content. Similarly, the ashes are used to make glass, mixed with bait to make soap or dissolved in hot water to clean canvases.

Medicinal

The eagle fern has certain metabolites that give it certain medicinal properties. In fact, it is used as an antidiarrheal, diuretic, laxative or vermifuge, in the case of amoebas or worms that affect the digestive system.

It is used as a hypotensive to regulate blood pressure, to relieve headaches and is effective in the case of glaucomas. In addition, it is recommended to relieve bleeding caused by prolonged menstruation and compresses or plasters of the fronds are used to heal and reduce swelling.

Tincture

The young fronds are used as a dye to color wool pale yellow, using potassium dichromate as a mordant. In the case of using copper sulfate, a greenish tone is obtained.

Illustration of Pteridium aquilinum. Source: Carl Axel Magnus Lindman / Public domain

Toxicity

Eagle fern fronds contain a wide variety of chemical compounds that are toxic to people who consume them in large quantities.

It contains the enzyme thiaminase, considered an antinutrient that destroys or prevents the absorption of thiamine or vitamin B ₁. It also has prunasin, which is a cyanogenic glycoside, and the flavonoids kaempferol and quercetin, carcinogenic substances with a highly toxic effect.

Regular consumption by cattle can cause internal bleeding, due to its carcinogenic and mutagenic activity. Even people who consume milk are predisposed to developing tumors of the stomach or esophagus.

Ruminants present with suppuration and bleeding from the nose, high fever, rapid pulse, general weakness, internal bleeding, bloody stools, and red urine. In equines, motor incoordination, tremors, lethargy, irregular pulse, collapse and seizures are observed, even death.

References

1. Eslava-Silva, F., Durán, Jiménez-Durán, K., Jiménez-Estrada, M. & Muñiz Diaz de León, ME (2020). Morpho-anatomy of the life cycle of the fern Pteridium aquilinum (Dennstaedtiaceae) in in vitro culture. Journal of Tropical Biology, 68 (1).
2. Pteridium aquilinum (L.) Kuhn (2019) GBIF Backbone Taxonomy. Checklist dataset. Recovered at: gbif.org
3. Pteridium aquilinum. (2020) Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
4. Pteridium aquilinum (L.) Kuhn (2006) Asturnatura. Recovered at: asturnatura.com
5. Pteridium aquilinum (2018) Connect-e: Sharing Traditional Ecological Knowledge. Recovered in: conecte.es
6. Sánchez, M. (2019) Eagle fern (Pteridium aquilinum). Gardening On. Recovered in: jardineriaon.com
7. Vibrans, H (2009) Pteridium aquilinum (L.) Kuhn. Mexican weeds. Recovered at: conabio.gob.mx