Pteridophytes (Ferns) in the Christopher B. Smith Preserve
Pteridophyte Characteristics: Pteridophytes are vascular plants (plants with xylem and phloem). Their leaves range from small and simple to large broad fronds with branched veins. Ferns have roots and sometimes true stems. They have alternation of generations with an inconspicuous, short-lived gametophyte (sexual) stage, and a conspicuous longer-lived sporophyte (asexual) stage. Ferns do not have flowers or seeds; they reproduce via spores. Thirty-five plant families and 568 genera are in this plant division. Members include terrestrial ferns, aquatic ferns, and epiphytic ferns.
Interactions in the Preserve: Like other plants, pteridophytes convert energy of sunlight to energy other organisms can use. The conversion process is photosynthesis. In addition, pteridophytes provide food and habitat for other organisms. Terrestrial fern roots hold soil in place which prevents soil erosion. Epiphytic ferns typically live at the base of palm fronds, where their roots help trap and hold forest debris that eventually becomes soil.
Family Species Name Common Name Blechnaceae Blechnum serrulatum Dryopteridaceae Nephrolepis multiflora Lygodiaceae Lygodium microphyllum Polypodiaceae Phlebodium aureum Polypodiaceae Pleopeltis polypodioides var. michauxiana Pteridaceae Acrostichum danaeifolium Osmundaceae Osmunda regalis Thelypteridaceae Thelypteris palustris Vittariaceae Vittaria lineta
Blechnum serrulatum is a native, perennial member of Family Blechnaceae. Although there are seven species of Blechnum in the United States, Blechnum serrulatum only occurs in Florida and it is one of the most common ferns found throughout much of Florida. Swamp fern lives in damp shady sites at the edges of wetlands and in hammocks. At the Smith Preserve, it grows along the filter marsh. The species can grow to a height of .3 to 1.5 m.
As shown in the photographs above, each frond consists of 20 to 40 paired leaflets with a single, apical leaflet. Fronds are pinnate and stiff. As shown at left, leaflets are crinkled with toothed edges. Fronds emerge directly from the soil. New growth is coppery pink and later becomes dark green.
Like other members of the genus Blechnum, and unlike most other fern genera, each individual fern has two different types of fronds, one is sterile and the other is fertile. Swamp fern spreads by spores and underground runners (rhizomes).
Asian Sword Fern
Nephrolepis multiflora is a non-native, naturalized perennial fern in Family Nephrolepidaceae. It is an aggressive invasive weed especially in hammocks. As seen in the third photograph above, Asian sword fern can be distinguished from Nephrolepis exaltata (native sword fern, aka wild Boston fern) by the dark brown scales at the base of fronds. Nephrolepis multiflora is included on Florida's Exotic Pest Council's 1999 List of Florida's Most Invasive Species as a Category I Invasive. This means it is invading and disrupting native plant communities in Florida. There is a large patch of this fern growing in the hammock to the north of the Smith Preserve's elevated entrance road.
Old World Climbing Fern / Climbing Maidenhair fern
Lygodium microphyllum is a non-native, invasive, climbing member of Family Lygodiaceae. The fern has dark brown, wiry rhizomes. In the second photograph above, a stem appears to be twining and climbing around itself and other vegetation. Actually this "stem" is a wiry stem-like leaf stalk of a branching fern frond that can grow to a length of 30 m.
Leafy branches off the main frond are 5 to 13 cm long and have compound, stalked, oblong leaflets. There are two types of leaflets; one type is unlobed and vegetative (as the leaflets shown at left), and the other type has tiny lobes of rolled leaf tissue at the leaf margins that contain sporangia. Sporangia produce spores.
Spores that land on the ground develop into gametophytes that produce sexual cells. Gametophytes are usually very small and rarely seen. Male and female sexual cells from gametophytes unite to form embryos that develop into new Old World Climbing Fern sporophytes.
Old World Climbing Fern is extremely invasive and spreading in Florida. The Florida Exotic Pest Plant Council lists Old World Fern as a Category I invasive. It alters native plant communities by smothering tree canopy and understory and creating thick mats on the ground.
Phlebodium aureum is a native, epiphytic fern that is a member of Family Polypodiaceae. As shown above, the fronds are bright green, large, and deeply lobed with up to 35 pinnae. This fern typically grows in the boots of Sabal palmetto (Cabbage Palm) and the crevices of Quercus virginiana (Virginia Live Oak.)
Its creeping rhizomes, shown in the top right corner of the photograph at left, are covered in golden-brown scales. These structures give Phlebodium aureum its common name, "Golden Polypody."
As shown in the two photographs below, a line of orange, round sori (a cluster of spore-producing receptacles) runs along each side of the bottom surface of a frond'smidrib. The spores are dispersed by the wind.
In Central American, golden polypody is used to make folk medicine tonics to treat asthma and heart disease.
Pleopeltis polypodioides var. michauxiana
This species lives from Florida north to New York and west to Texas.
It, like Phlebodium aureum, is an epiphyte. As such, it absorbs water and nutrients from the outer surface bark of large trees like cypress and live oaks.
As shown in the first photograph, it survives long drought periods by curling up. When water is present, it uncurls and "resurrects," as shown in the photographs below.
Resurrection fern has a long stem and 10 to 30.5 cm long evergreen fronds. Fronds are made of small, rounded, oblong blades. Spores are in clusters (sori) on the bottom sides of the blades. Sori look like dark scales.
Florida is the only state where Acrostichum danaeifolium exists. It thrives in semi-aquatic habitats, where it tolerates different exposures of sunlight (full sun to full shade). It cannot tolerate freezing temperatures. In the Smith Preserve, individuals grow along the margins of the filter marsh.
Acrostichum danaeifolium can be up to 3.5 m tall and nearly 2 m wide. Fronds are pinnately divided into 20 to 60 pairs of leaflets. Each leaflet is dark green on top, pale green on the bottom, and leathery. There are two types of fronds, fertile and non-fertile. Fertile fronds are taller and more erect than non-fertile. As shown in the photograph above, on the bottom of the leaflets of the fertile fronds are mats of golden brown or reddish spore cases which give the fronds the appearance of having a suede undercoating.
Potential pests of the leather fern include scale insects and slugs.
Old World Royal Fern
Osmunda regalis is a non-native, deciduous fern that normally grows in bogs and along stream banks. Its width is equal to its height: .6 to .9 m. It grows in partial shade to full shade and produces separate fertile and sterile fronds.
As shown in photographs 1 and 2, sterile fronds are spreading. Photograph 3 shows a leaflet from a sterile frond.
As shown in photographs 4 and 5, fertile fronds are erect and shorter. The species is sometimes called the "flowering fern" because its fertile fronds resemble flowers. Spores are in brown clusters at the tips of the fertile fronds.
The common name of Osmunda regalis, "royal fern", is derived from being one of the largest and most imposing European ferns. "Old World" is used to distinguish it from the American Royal Fern (Osmunda spectabilis).
Osmunda spp. roots are fibrous and used as potting medium for cultivated orchids and other epiphytes.
These photographs were taken in the Smith Preserve on March 6, 2012. The species was identified from these photographs by Roger Hammer, author of Everglades Wildflowers and Florida Keys Wildflowers on April 27, 2014.
Thelypteris palustris is a native fern member of Family Thelypteridaceae (The Maiden Fern Family). It grows in sunny marshes, swamps, and wet ditches to a height of about 1 m. The species name palustris means "marshy or swampy." The individual shown in these photographs is growing at the northeast corner of the Smith Preserve's western-most filter marsh in the wet soil along the edge.
The stipe of eastern marsh fern is straw-colored or darker. The fern is slender with pinnate fronds. Each compound leaf has 10 to 40 pairs of leaflets. The leaflets are oblong or oblong-lanceolate in shape and the margins curve down. The rhizome is long, creeping, and branching. Spores are located on the underside of the fronds in sori that appear as rows of dots near the midvein.
Because this fern often forms dense clusters of leaves, it provides good cover for the small animals.
Vittaria lineata is a native perennial member of Family Pteridaceae. This epiphyte has short, branched stems and brown scales. The fronds are ribbon-like, flexible, tapering, 10 to 60 cm long and 1 to 3 mm wide. The generic name Vittaria is derived from the Latin word, "vitta", which means "a band or ribbon." Shoestring fern usually grows in moist areas of the bootjacks of Sabal palmetto (Cabbage Palm).
As shown in the photograph at left, the bottom surface of the fronds have two grooves that contain many small reddish brown sori. Sori are clusters of sporangia. Sporangia are enclosures where spores form. In the photograph at left, yellow spores fill the grooves.
© Photographs and text by Susan Leach Snyder (Conservancy of Southwest Florida Volunteer), unless otherwise credited above.
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