I Covet my Neighbors' Ebony Spleenworts!
I love ferns: all kinds of ferns. There's something relaxing and refreshing about enjoying these woodsy plants just for their fronds, since ferns are so primitive they do not flower. The evergreen Ebony Spleenwort (Asplenium platyneuron) flourishes here in northern Florida. I transplanted some to several areas, including my rain gardens. Even though my transplants are doing well, they pale next to the lush displays in some of my neighbors' yards.
(Update: Those ferns that I liked so much were not the delicate spleenworts that I knew in Maryland, but the invasive tuberous swordfern (Nephrolepis cordifolia ). I removed my new populations as soon as I discovered this and I have continued to remove it in the wooded areas between our house and our neighbor's.)
Fern life cycle
The fern life cycle has two stages: the gametophyte and the sporophyte. The one we notice is the sporophyte, so named because it produces spores (the dust-like, one-celled particles) by the millions. Spores are produced in sacs called sori (plural of sorus), located on fertile fronds that may or may not resemble sterile fronds, depending on the species. The unequal drying of the alternate thick and thin-walled cells that line the outer surface of the sori causes miniature explosions to disperse the spores. At that size scale, the expulsion of fern spores is said to be one of the more explosive events in nature.
When the wind-blown spores land on suitable places, such as moist soil or cracks in rocks, they germinate into small, heart-shaped gametophytes with male and female parts. Gametophytes are always small because they have no vascular parts and must absorb any moisture directly by osmosis. The male parts produce flagellated sperm that need moisture to move. A new sporophyte is the product of that fertilization.
Given this complex process, is it any wonder that ferns normally spread via well-developed rhizomes? Ferns multiply asexually and most ferns you purchase have been divided from cultivated fern stocks. You may multiply your ferns by dividing them. It's a mathematical oxymoron.
The fronds of the ferns are normally divided into leaflets. Singly pinnate fronds such as the Spleenworts and Resurrection Ferns have one main stem with rows of leaflets on either side. A doubly pinnate frond means that the leaflets are divided again into sub-leaflets and so forth.
Many of the ferns that grow here in northern Florida also grow in Maryland, so they are not strangers. Here are some of my other favorites:
Cinnamon Fern (Osmunda cinnamomea)
This large bunching fern growing to three or four feet under the right conditions, sports its cinnamon stick-type, spore-laden, fertile fronds in both the fall and the spring here. The fertile fronds wilt away after the spores are released leaving the green fronds for us to enjoy until frost when they die back for the winter. Of course, winter is much shorter here in Florida, so we have a longer fern cycle. In Maryland I never saw fertile fronds in the fall. This beauty can survive in nearly full sun to full shade, but it's happiest in moist soil. I'd categorized this as a specimen fern, not a ground cover like the Spleenworts.
Royal Fern (Osmunda regalis)
Another large, specimen fern, this one is truly regal in its size, growing to three to five feet: even larger than its close relative, the cinnamon fern. The royal fern's doubly pinnate fronds have more widely spaced leaflets making it appear lacier.
The fertile sections of this fern appear at the top of the main fronds. After the spores are released, the tops will fall off. The royal fern doesn't seem to be as tolerant of full sun as either the spleenworts or the cinnamon ferns, but partial sun is fine and it does best with its feet wet.
The Netted Chain Fern (Woodwardia aerolata)
This spreading fern is a wonderful groundcover forming dense, one-foot high mats in the forests. It grows in full shade to mostly sun. Its fertile fronds start out like a regular leaf, but then curl inward, turn a rich, shiny brown, and grow taller than the sterile fronds. The sterile fronds die back in the winter leaving only the stiff fertile fronds in place.
Its fronds are singly pinnate meaning that its leaflets are not again divided. This provides a less lacy and courser appearance than most other ferns. In planning a garden-space, you want to provide a variety of textures.
Bracken Ferns (Pteridium aquilinum)
Brackens thrive in much drier locations than most other ferns, and one source stated that brackens are the most abundant fern worldwide. Some of the bracken clones are estimated to be hundreds of years old.
Farmers consider brackens to be noxious weeds because they have deep, aggressive rhizomes that sprout new plants from small pieces, resist fire and are toxic to grazing animals.
Bracken fronds are triply pinnate and are more triangular in shape than most ferns. "Pteridium" is a diminutive of "Pteris", Greek for "fern", and "aquilinum" is from the Latin for "eagle" and refers to the wing-like fronds of this fern.
Over the years, I've found it impossible to transplant a bracken and I haven't seen it for sale, but I was happy to see it growing in a wooded area in front of the house.
The Resurrection Fern (Polypodium polypodioides)
This was a new fern for me. I never saw it in Maryland. And unlike the other ferns in my list, this one is an epiphyte, which means it doesn't require soil. In fact, these little ferns, growing only to four to six inches, seem to occur most frequently on the tops of the more horizontal branches of live oaks (Quercus virginiana). Most of their lives, they look dead, but as soon as there's water they spring back to life, hence the common name.
As I said, I like all types of ferns. They just seem so calming somehow because in a garden, you are never expecting a flower and are content with their interesting foliage. I was happy to find a good variety of ferns around our house and will continue to encourage them.
Ginny Stibolt moved to northeastern Florida in 2004 and even though she's a botanist and lifelong gardener, Florida gardening was a shock. She started writing The Adventures of a Transplanted Gardener columns for the Times Union newspaper in Jacksonville. This is one of those columns archived here on Floridata.com for your enjoyment. Now she's written three Florida garden books published by University Press of Florida: Sustainable Gardening for Florida, 2009; Organic Methods for Vegetable Gardening in Florida with Melissa Contreras, 2013, and The Art of Maintaining a Florida Native Landscape, 2015. Check out her blog for the latest news and articles: www.GreenGardeningMatters.com