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| In Florida, the endangered Adiantum melanoleucum is known only from Miami-Dade County. This fragrant maidenhair is said to have a sweet aroma when crushed, but it is so rare that I don't want to disturb it. |
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| The South Florida endangered endemic Trichomanes punctatum ssp. floridanum, or filmy fern, looks more like a liverwort than a fern. |
South Florida Ferns
Jennifer Possley, M.S., GIS Lab Coordinator / Field Biologist
A few months ago, I took a new position at Fairchild which involved monitoring rare plants on Miami-Dade County lands. Although I have been working with sub-tropical plants for quite some time, this work has given me many surprises and shown me how much more I have to learn about South Florida and its flora. One of the things that has struck me most is how many of the county's rare plants are ferns. In Miami-Dade County, the construction of canals has dried up much of the habitat, and urbanization has completely destroyed a great number of the limestone formations that once supported fern colonies. However, if you visit areas where rivers formerly flowed freely, the intricate nooks and crannies of the old limestone banks still support the remnants of what once must have been an amazing variety of ferns.
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| The author surrounded by Acrostichum danaeifolium, the giant leather fern, in the dry bed of the Deering Estate's Cutler Creek. |
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| Double treat: a sinkhole is populated with the endangered ferns Tectaria fimbriata, the least halberd fern, and Lomariopsis kunzeana, the holly fern (found in Florida only in tiny populations in Miami-Dade County). |
Ferns, a sister group to all flowering plants, were one of the first groups of land plants to evolve, millions of years ago. Florida's diversity of ferns is unrivaled by any other location in the continental U.S. The State of Florida is home to more than 120 native ferns; many of them grow in South Florida. The main reason this area has so many species of ferns is the variety of habitats offered by the unique limestone formations of the Miami rock ridge. Sinkholes, solution holes and cliffs provide an ideal substrate for many of these green, lacey plants.
Miami-Dade County is embarking on an exciting restoration project for one such former wetland, the Deering Estate's Cutler Creek. The first phase of this project involves the installation of a small dam (or "weir") at the east end of the creek, which flows through the hammock. As the field biologist monitoring rare plants on county lands, I (along with other biologists from Fairchild and the county) get the opportunity to be involved in this project by observing the vegetation changes that may be caused by installation of the weir. And first on the list of plants to be affected (positively, we hope!) are ferns.
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| Thelypteris reptans is an endangered fern that reproduces by a mode unique to the genus - on the end of long fronds, it creates plantlets which root separately. | Fairchild field botanists Kristie Wendelberger and Adrianna Muir are working on the Cutler Slough rehydration project, studying the ferns adjacent to Cutler Creek. |
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| This limestone outcropping is a beautiful reminder of a time when water flowed freely through Miami-Dade County, carving out the Miami Rock Ridge and creating a haven for ferns. | Ferns reproduce by spores that are usually borne on the underside of the leaves. The spores on this relatively common Campyloneureum phyllitidis, the long strap fern, are ready to pop! | The endangered Odontosoria clavata is also called the wedglet or parsley fern. This delicate fern bears spores differently from most ferns: They are found in cup-like structures at the ends of leaf segments. Botanist and explorer J. K. Small wrote of discovering a large population of this fern in a Miami-Dade County hammock: "... the rocky floor was literally carpeted with this fern. It grew so luxuriantly that deer would lie in the dense beds and several times they arose from their ferny beds only a few feet in front of us as we approached." He goes on to say that this population was extirpated by urbanization. |
Ferns are exciting and sometimes a little intimidating, too. Since they are not flowering plants, they can be difficult to distinguish visually and even taxonomically. Further, many species hybridize to form unique varieties that are intermediate between their parents in morphology. However, I have found they repay the effort it takes to learn about them. In the last few months of taking notes, memorizing features, attending Florida Native Plant Society workshops, and taking photos, I have become increasingly fascinated by South Florida's extraordinary ferns.
Locating and identifying ferns was greatly facilitated by Keith Bradley of The Institute for Regional Conservation and Steve Hofstetten formerly of Miami-Dade County Department of Environmental Resources Management
Data on ferns in South Florida is from:
Nelson, Gil, 2000
Ferns of Florida,
Pineapple Press, Inc., Sarasota, FL
Small, J. K., 1929
From Eden to Sahara: Florida's Tragedy,
Science Press Printing Company, Lancaster, PA.
Garden Views Summer 2003