Ferns

Underside of fern frond with sori visible
Underside of resurrection fern with sori visible.  Sori contain spores that are the fern's method of reproduction.

NPS Photo


Looking around the forests and clearings of Fort Matanzas National Monument it is easy to spot a variety of different plants, all of which have adapted to their local environment. One type of vascular plant that is more primitive than most are ferns. By definition, ferns are plants without flowers or seeds. They have feathery leaves (fronds) and reproduce by spores released from the underside of the leaves. Here at the park there are four different fern species present, all of which are noteworthy in their own right.

Resurrection Fern
This fern is an epiphyte, meaning it grows on other plants (usually live oaks or cypress trees). They do not commandeer any water or nutrients from the plants they grown on; instead they absorb them from the surrounding air. In periods with no rain they conserve water by shriveling up their fronds and turning brown. Once sufficient moisture soaks the area they open up with fronds of vibrant green again. Because it looks like they come back to life each time this happens, they have received the common name of resurrection fern.

Bracken Fern
This is a perennial fern (meaning it has a life span greater than two years) and is found all around the world in a variety of habitats - dry to wet forests, clearings, sandy soils, roadsides, lakeshores, swamps, and burned areas. Because they have underground stems called rhizomes, they are able to survive fires and re-sprout after the fire has passed. Many cultures have used this fern as a food source; however, it has been said to increase the risk of cancer. This fern is also potentially toxic to animals, especially livestock like horse and cows.

Golden Polypody
Another epiphyte, it is often seen growing on the trunks of sabal palms. They are rarely found growing directly in soil but it is not unheard of, especially in a swamp or moist forest setting. They are usually green or blue-green in color and have gold-colored scales along the stems. Chemicals present in this fern species have been studied for their ability to improve skin cell membrane integrity, and thus may protect against premature wrinkles due to unprotected sun exposure.

Chinese Ladder Brake
Chinese ladder brake is a non-native fern species that originally came from China, as its common name implies. This fern is good at growing in every corner or tiny chink it can find on stone structures (including on the walls of Fort Matanzas!). However, it has been put to beneficial use in some environmental remediation situations because it happens to be a hyperaccumulator of arsenic. It is capable of growing in soils with a high concentration of the toxic metal and absorbing it through its roots and concentrating the arsenic in its fronds. They have accordingly been planted in contaminated sites to bring the environment back to a less toxic state. Understandably, these ferns can be poisonous if ingested.

Whether any of these ferns are growing in your backyard or in one of our nation’s national parks, each one is deserving of study and recognition of its unique properties and its place in the overall ecosystem, regardless of its practical use to humankind or not.

Last updated: October 20, 2015

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