Dr. Percival Lowell, in one of his books, (Mars as the Abode of Life), tells us that, “When the earth was young and still so warm that it was continually enveloped in a thick blanket of steam-warmer everywhere than at the tropics to-day, yet cool enough to support plant life-in the vast marshes which made up so large a portion of the continents, cryptogams composed the greater part of the vegetation attesting by the habits of the ferns of to-day the shady half-light in which they must have lived”.
This gives the impression that ferns are relatively primitive, dominating Earth long before seed-bearing plants and flowers appeared. However we can tell from the fossil record that ferns have changed substantially over time with some modern species showing recent appearance and adaptation to conditions that are often not moist or mild. They have adapted themselves wonderfully to changed conditions in the course of ages. This requires a powerful ability to withstand cataclysmic climate change and survive.
The far-famed fern
Picture 1: Phlebodium aureum growing in the Tropical Glasshouse at Reading University
The Fern, which we are celebrating here, is Phlebodium aureum (L.) J. Sm. has many common names in different languages and this is not surprising since it draws the attention to its beauty and ubiquity to be cultivated as oriental plant long times ago. In English it has got about six common names; gold-foot fern, golden polypody, hare-foot fern, rabbit-foot fern, golden serpent fern and cabbage palm fern. Other common names in other languages including: calaguala (Spanish language), laua`e haole (Hawaiian), samambia, and hartassbräken (Swedish), (GRIN, 1998). Those names refer to the golden-brown colour and the shape of this fern.
A dose of Taxonomy
Botanically, Phlebodium aureum has two synonyms; Polypodium aureum and Polypodium leucatomos. The taxonomy classification for it is Plantae; Pteridophyta (=Pterophyta); Polypodiales; Polypodiaceae.
Speaking on taxonomic side, Polypodiaceae are commonly called Polypods. Recent molecular phylogenetic analysis has led to the division of the Polypodiaceae into five subfamilies (Smith et al., 2006), and to the inclusion of genera that have at various times been placed in other families. It contains 56 genera and 1200 species. Mostly epiphytic and epipetric, a few terrestrial; widespread. Generic boundaries need clarification, and, in particular, Polypodium and Microsorum, two of the largest assemblages, are known to be polyphyletic. Certain previously misplaced genera are now shown to be nested within Polypodiaceae, e.g., Pleurosoriopsis and Gymnogrammitis.
A look into morphological features
To turn now to the more practical part of our subject let us see the features distinguish this ferns from others. This fern has creeping Rhizome, up to 3 cm in diameter; densely covered in the golden-brown scales that give the species its name, long-attenuate, up to 2 cm long. The fronds (leaves) are large and pinnatifid (deeply lobed), from 30–130 cm long and 10–50 cm broad, with up to 35 pinnae; they vary in color from bright green to glaucous green and have undulate margins, with a few scales near base . Lamina deeply pinnatifid into 8-16 (up to 35) pairs of pinna with a terminal segment, bright green or glacous. Lobes lanceolate to elliptic to linear in outline, apex pointed, venation reticulate, forming distinctive polygonal areoles, margins entire. Sori round, c. 2 mm in diameter, in 2 rows on each side of the costae, situated at the junction of 2 included veinlets, exindusiate. 2 n = 148.
Where? (Habitat & Distrbution)
This fern is rarely terrestrial in habitat, usually colonizing the canopies of tropical rainforests and the dwarf palms of subtropical forests. It is common in the cloud forests of the Caribbean and northern South America. It grows in varied habitats in Florida, including swamps and hammocks, and can thus apparently tolerate a wide range of microclimates. Its restriction to the tropics and subtropics is readily explained by its intolerance of anything other than very brief, light frosts. High levels of light are also critical for growth of this species, and its deciduous habit allows it to invade relatively dry areas.
It is native to tropical and subtropical regions of the Americas. It is confined to the eastern side of the continents, extending north into the United States to Florida and the extreme southeast of Georgia and south through the Caribbean, and northern and eastern South America to Paraguay. It is the only species of Phlebodium found in North America, the other species all confined to South America. It is naturalized in Hawaii and introduced recently in the Cook islands (GRIN, 1998).
Cultivation and uses
Phlebodium aureum is well-adapted to cultivation and is valued both as an ornamental plant and in herbal medicine. It can be cultivated in greenhouses in non-tropical climates if night temperatures do not fall below about 5 °C. Several cultivars have been selected for garden planting, with varying leaf colour from grey-green to silver-green to blue-green, or with cristate or very wavy frond margins (Wikipedia, 2013).
The medicinal qualities of ferns, real or imaginary, we find mentioned as early as 300 B. C. by the Greek philosopher Theophrastus and the rabbit-foot fern is not an exception. The plant historically has been used by the indigenous people of Honduras for malignant tumors, rheumatoid arthritis, and psoriasis. In the Amazon rainforest a maceration of the rhizome is used for fever; grated fresh, it is made into a tea for whooping-cough and kidney problems. The Boras Indians (in the Peruvian Amazon) prepare the leaves in a drink for coughs. The Witotos Indians (in the northwest Amazon) use the rhizome for treating coughs. Other Peruvian indigenous tribes use the rhizome for problems of the pancreas. Indigenous groups in Latin America use the rhizome and leaves for many different maladies including cancer, psoriasis, peptic ulcers, kidney problems, diarrhea, arthritis, and pains in joints and tendons. It is generally considered throughout the Amazon to be a general tonic, to detoxify the body, and to support the immune system (Taylor, 1996 onwards).
Beware of side effects & safety..!
Phlebodium aureum seems to be safe when used appropriately for only two days. The safety of long-term use is not known. There is very little information available about possible side effects of Phlebodium aureum. It may cause upset stomach in some people.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the use of Phlebodium aureum during pregnancy and breast-feeding. Stay on the safe side and avoid use.
Note: Pictures shown here by Zawan AL Qassabi from plants in the Reading University tropical green house and the Herbarium (RNG).
References
Smith, A.R., Pryer, K.M., Schuettpelz, E., Korall, P., Schneider, H., Wolf, P.G. (2006). A classification for extant ferns. Taxon. Vol. 55, No. 3, pp. 705-731.
Starr, F. and K. Starr. Plants of Hawaii. Starr Environmental . Phlebodium aureum. URL: http://www.starrenvironmental.com/images/species/?q=phlebodium+aureum&o=plants . [30/10/13].
Taylor, L. (1996). Samambaia. URL: http://www.rain-tree.com/samambia.htm[25 October 2013].
USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network – (GRIN) [Online Database] (1998). Phlebodium aureum. URL: http://www.ars-grin.gov/cgi-bin/npgs/html/stdlit.pl?F%20NAmer [30 October 2013]
Wikipedia: The free Encyclopedia (2013). Phlebodium aureum. URL: http://en.wikipedia.org/wiki/Phlebodium_aureum#cite_note-grin-1 [25 October 2013].