Ferns tough out their space in the Turks & Caicos Islands bush

Story & Photos By B Naqqi Manco, TCI Naturalist

As a child of the late 1970s, I feel fortunate to have barely missed some of the most iconic and horrid trends of the decade—the hair, the clothes, the odd novelty gifts—I was too young then to be taken in by them. But I clearly remember one remnant of the Disco Era that made a significant impression on the mind of a budding naturalist. Hanging from the dining room wall, opposite a matching hideously utilitarian chrome Contemporary chandelier, was a three-bowl, vertically stacked chrome planter holding three plants of the most unbelievable colours: Leprechaun green, goldenrod yellow, and flapper-dress magenta. The small plants were tough, supple and fleshy, and branched upwards and outwards toward my mother’s collection of Royal Doulton face steins and Bunnykin figurines. My parents called them “air ferns,” and despite my compassion-rooted protests, insisted that they needed neither soil nor water to survive, and fed only on air. They looked alive, and felt alive, and so I eventually subdued my scepticism enough to allow the air ferns to sit in their shiny silver planter . . . but I never stopped checking to see if they had grown, or branched, or given any other sign of life.

Of course the popular “air ferns” of Contemporary 1970s home decor were not actually alive, which I discovered only upon remembering and investigating a few years ago. They are, in fact, not even plants, let alone ferns. Schlepped up by fishing vessels in the North Sea (a bi-product of bottom-trawling), the dead skeletons of hydrozoans (animals related to corals) are dried, dyed obnoxious colours, and packaged as eternally living, completely care-free plants.

True ferns are not so carefree, as the few struggling to survive on my dresser can attest. Ferns are special plants—they are ancient in evolutionary time, and they are stuck somewhere on the scale of complexity between non-vascular mosses and higher flowering plants. They have a remarkably complex life cycle, one that involves a totally separate form of life to create the fern, and they grow in strange and unexpected places. Mostly, those places are moist, humid, and shady—and locations of this sort are restricted, in the Turks & Caicos Islands, to a few micro-habitats in sinkholes, caves, a few dense tropical forests, and dank wells. Due to the restricted size of these micro-habitats, ferns are not especially common in TCI. Only a handful of species grow here, and some are quite unexpected in terms of form or habitat. Some are perennial, leafing out only after hurricane season rains and surviving as crusty brown rhizomes for the remainder of the year. One even “dies” seasonally, only to spring back to life when drenched.
When actively growing, ferns can be identified by a few common characteristics. First, ferns have buds that uncurl as they grow, resembling the scrolled carvings on the ends of string instruments—and named, logically, fiddleheads. Second, ferns do not usually grow a branching, upright stem or trunk, but rather hide their main stem underground or closely pressed onto a log, tree, or rock. Third, ferns are not flowering plants. They produce no flowers, fruits, or seeds. Their eccentric method of reproduction involves two distinct life stages and a strangely animal-like fertilisation process.
To reproduce, ferns produce button- or capsule-like structures that yield spores, tiny genetic particles that can fly away on a slight breeze. Sometimes these structures are on the underside of mature leaves, often arranged in regular patterns. Other times, the structures are separate and can even resemble seed pods—but spores are not seeds. A seed is a fertilised plant embryo, with genetic information from two parents. But a spore contains only genetic information from the plant that produced it—it bears half the chromosomes it needs.
If a spore lands in the right place, it will begin to grow, but not into a fern. It grows into a small, disc-shaped, fleshy green blob that looks more like algae than a land plant. This little creature, called a gametophyte, produces the species’ sex cells—eggs; and not pollen, but flagellate, mobile sperm cells. When drops of rain or dew wet the gametophytes, the liquid allows the sperm cells to swim to other gametophytes and fertilise their eggs’ cells. Only when a gametophyte’s egg is fertilised will it form a fully-functional life form that grows into a mature fern. The gametophyte, something which few people have seen or would notice, dies as the fern grows roots and leaves called fronds. This is why ferns need moist, damp locations to grow—their bizarre reproduction method depends on an abundance of water to facilitate fertilisation.
All of this un-plant-like hanky-panky behaviour means that ferns are not as simple to grow as plants that grow from seeds. Fern spores in horticulture have to be grown in sealed containers of sterilised peat moss, and it can take months for the gametophytes to form. When they do form, they require rain-mimicking hand-misting to allow the fertilisation of the eggs to take place. Finally, tiny ferns will grow from fertilised gametophytes, and then one has the challenging task of keeping the fern alive.
The Victorians developed these and further methods for keeping ferns from dying. They even went through a gardening period called pteridomania, an obsessive collecting and displaying of not only live ferns in gardens, homes and glasshouses; but also of fern motifs on everything from stationery to textiles, from dishes to gravestones. The Wardian case, a miniature glasshouse originally developed to transport live plants from tropical colonies to England on the decks of sailing vessels, became the preferred device of fern culture to protect them from the Victorian period’s industrial smoke. Terrariums for ferns also became popular, as were entire specially-designed glasshouses to display ferns. Collections of ferns (and later orchids) from around the world became a conspicuous consumption luxury of the wealthy, and led to the decline in the wild of several of the more popular species. Fortunately, the aforementioned culture methods were discovered, which allowed for the domestic production of ferns to feed into the botanical demands of the time.
One of the most popular and well-remembered ferns of the pteridomania period is the long strap fern Campyloneurum phyllitidis. Recently confirmed to exist in the Turks & Caicos Islands for the first time, this stately, un-fern-like fern occurs from South Florida, through the Greater Antilles, and into Central and South America. It is classified as rare in the Bahamas. Previously thought to be absent from the Turks & Caicos Islands, the fern is now known to occur in North Caicos, where it was discovered in February 2012. Two large individuals were located by the author south of Kew Settlement in a low, rich area, attached firmly around the lower parts of tree trunks. The long strap fern is an epiphyte (like many of the ferns in Turks & Caicos), meaning it attaches itself to a tree for support. Residents of Kew Settlement confirmed that the plant is known from a few other locations, including low areas around “oak bottoms,” or temporary rain-fed pools surrounded by wild oak trees Bucida buceras.
The strap fern was formerly classified in the large genus Polypodium, which has been broken up into several genera that included two of our other rare native ferns. The rabbit’s foot fern Phlebodium aureum is another large and stately fern, named for its fuzzy auburn rhizomes which look like “lucky” rabbits’ feet. Also called the serpent fern, the large lobed leaves are usually shed in the dry season and leaf out to appreciate the hurricane season rains. Bright orange buttons of spores are lined up on the bottoms of the fronds. In much of its range, this fern inhabits one specific habitat niche—growing in the labyrinth of burlap and cork at the crown of big top palms Sabal palmetto. In the Turks & Caicos Islands, our big top palms grow in areas too dry and exposed to host this fern, but they can be found, rarely, gripping the bottoms of trunks of small trees in the gallery forests around Kew, North Caicos and clinging to the inner walls of the deep, ancient wells of the same settlement. The fronds can grow to nearly a metre long, making this fern an obvious feature in the few spots it occurs.
Another epiphytic fern that resembles the rabbit’s foot fern but is significantly smaller is the rather miraculous resurrection fern Pleopeltis polypodioides. While its fronds are only a few centimetres long, and it clings rather subtly to rough tree branches and logs in a very small area of North Caicos (namely, around the ruins of Teren Hill Plantation), the resurrection fern’s well-deserved namesake proves to be an amazing phenomenon. In times of drought, the little resurrection fern does what most plants do when they do not get enough to drink—the fronds shrivel and desiccate, becoming crispy, dry skeletons, sadly bent over and folded in surrender to drought, looking like some tragic plant relic from a Dr. Seuss-inspired desert.
But a simple downpour transforms these skeletons. Unlike other plants that die when they become crispy, the resurrection fern is able to absorb water right into the very same leaves it used in the previous rainy season— inflating with water, greening up, and becoming alive again. During the short part of the year that they are able to exist fleshy and lush, the resurrection fern grows, its slender, wiry rhizomes creeping through and under furrowed bark of large trees and logs.
Ferns often like to grow on the trunks of trees, and one fern that is very rare in TCI—so rare that only one specimen has ever been found—enjoys clinging to life on the side of a tree along with a bracket fungus. The lobate armoured fern Tectaria lobata has just a few maple-like leaves, but it seems TCI’s alternative droughts and hurricanes in the last few years proved too much for it to take, and TCI’s only known specimen seems to have disappeared.
Not all ferns are rare though. The profanely common Boston fern Nephrolepis exaltata, which has been extensively cultivated as a houseplant, is found throughout TCI, sometimes in very unexpected places. It grows from beneath stones in quarries, as a weed on the floors of nurseries, from the moist walls of water cisterns, and even in the branches of trees. While this plant is native to the Caribbean region, it may have made its way around the TCI more from spores released from cultivated house or garden plants.
Another fairly common fern in TCI is the southern shield-fern Thelypteris kunthii. This fern is especially common in wells and caves, where it can grow quite large. A verdant bed of southern shield-fern can be seen at the bottom of Charles Rigby Hole in Middle Caicos south of Lorimers, but don’t take too close a look—the hole is undercut and impossible to enter or exit without full climbing gear! This fern can also be found in moist, shady locations such as old cisterns and leaky cistern walls. In its habitat, it can be very common.
Even more ubiquitous worldwide is the fern known as bracken Pteridium aquilinum. Bracken is considered one of the most widespread plants in the world, and it is an extremely successful invader of all sorts of otherwise undesirable habitats. Not only can it survive on very low soil nutrients, but it is resistant to both drought (its leaves are extremely tough, and can shed), fire (the stems remain over a foot underground, only the leaves emerge), plant competition (it releases growth-inhibiting chemicals into the soil around its roots that can persist for a decade), and insects (its chemical defence includes naturally-produced cyanide). Bracken occurs usually in open areas, such as pine yards and palmetto flats, but is occasionally found in forest shade as well. One large stand in North Caicos creates what is called a brake, or thicket, that is singley populated by this species. Bracken’s usual success story is that when it colonises a barren habitat, it overcrowds and poisons any other plants and animals out of the way. The fronds are usually about three feet tall in TCI, but in some cases can grow to eight feet high, making it one of the largest ferns in TCI.
A fern larger than bracken, (far more massive in fact), is also found in TCI. The leather fern or swamp fern Achrostichum aureum may be found growing in low, wet areas beside borrow pits and inland blue holes in the Caicos Islands; sometimes it even grows right in the water with its feet wet. With gigantic fronds stretching to eight feet in typical length, covered with broad, fleshy leaflets, this fern is a champion among TCI ferns. A luxurious stand of leather fern can be seen wreathing the perimeter of Cottage Pond in North Caicos, where it provides a respite for birds such as common gallinules and least grebes. It is found in several other similar situations, but Grand Turk residents can get a good look at a massive specimen that grows in the fountain in the Secret Garden restaurant of the Salt Raker in Grand Turk. This particular specimen was taken to Grand Turk as a tiny sporeling(?) and has grown to mammoth proportions, having survived Hurricane Ike and pleasing diners with its elegant, swooping fronds.
Ferns are rarely aquatic like the leather fern, but Nash’s pepperwort Marsilea nashii is a real rule-breaker. Not only is this fern aquatic, but it doesn’t look like a fern at all. The fronds grow thin, wire-like stems, topped with four identical leaflets in a sort of four-leafed clover arrangement. Even less fern-like, the pepperwort folds its leaflets together each evening, going to sleep for the night. It is not a large plant; the fronds top out at about ten inches in height, and that’s only when the plant is extremely well-watered and fed. A botanist colleague from Royal Botanic Gardens, Kew once found a tiny specimen of it in a dry pond bed, and asked me what member of the legume family it was. I had to find a fiddlehead of new growth to convince him it was indeed a fern!
Although usually found on moist banks of ponds, the pepperwort also happily grows underwater, extending its frond’s stems upwards so the leaflets float on the water surface like shamrock-shaped lily pads. Try pushing the lily pads underwater, and the plant reveals its special waterproofing trick—tiny hairs on the leaflets repel water in a silvery sheen, keeping them forever floating and never wet.
Nash’s pepperwort grows in low, rich, fresh-water environments, only in the TCI and the Inagua islands in the Bahamas. Both of these island groups are low on freshwater habitats and so the fern is not particularly common. Also, freshwater ponds in TCI tend to dry up seasonally—but the Nash’s pepperwort has a solution to this problem. Turning red to shield its tender leaves from too much sunlight, the fern reduces its new frond size until the entire plant shrinks down to the size of a quarter. It may even dry up completely and die.
But this death is a sort of temporary state. The pepperwort does not produce spores on its fronds like most ferns. This odd little fern produces sporocarps, which are little fuzzy pods at the base of the fronds along the creeping stems. These pods hold the sorus, a spore-producing tissue. When the conditions are dry, the sporocarps lock tight. But when rains flood the soil and submerge the sporocarps in water, the pods open and the sorus begins to grow. Snaking out of the pod like a mucous serpent, the sorus extends into the water, produces spores which immediately form into gametophytes underwater, and fertilisation occurs in a sub-aquatic orgy of thousands of gelatinous wormy fern members. The juvenile pepperworts often grow directly along the sorus until it disintegrates, then they float away to grow elsewhere. As if this method of reproduction was not admirably adaptive enough, the sporocarps are known to last when dry, fertile and fecund, for over a century.
Nash’s pepperwort can be found in most of the TCI, but a remarkable lawn of this plant occurs at Grand Turk’s North Wells. Pass your hand carefully among the grasses and rushes and fog-fruit verbena all dwarfed by constant grazing of hoofed animals toward the south end of the well site, and soon the tiny four-leafed clovers will become apparent. A single strand of the pepperwort stem transferred into a flowerpot full of mud and kept adequately soggy will soon bloom into a lush, dense mound of lucky little clovers!
Nash’s pepperwort can also be encountered at the South Wells of Grand Turk, in wells and pools along Back Road in South Caicos, and in the Garden Ponds of Middle Caicos. It is one of my favourite plants, for its unusual appearance and ease in care. I have a few dense pots full of it myself, and at one time had a rather frighteningly wild mound of it inhabiting a gigantic washtub full of peat moss and rainwater. It prefers bright sunlight and ample water, so a fancy circa-1976 chrome hanging wall planter in a shadowy dining room just won’t do for it, as it did for my mother’s air ferns. I’ll keep enjoying this amazing little plant in its outdoor setting, knowing that it is not only more alive than those ersatz Technicolor air ferns, but also has a far more intriguingly sordid reproductive life.