The Resurrection Fern often blankets the limbs of mature trees, leading many homeowners to worry that the plant is slowly strangling or poisoning its host. The concern is understandable, as the fern’s appearance changes dramatically, seemingly dying and reviving with the weather. Understanding this unique plant and its relationship with the tree answers the common query about its potential for harm. This organism is not a threat to the health of a sound tree, but rather a harmless cohabitant of the forest canopy.
Defining the Resurrection Fern
The Resurrection Fern (Pleopeltis polypodioides) is a small, low-growing fern commonly found across the Southeastern United States, extending as far west as Texas and north to Delaware and Kansas. Its fronds are typically lance-shaped and measure between 4 to 12 inches long, spreading widely by slender, creeping rhizomes that anchor it to surfaces.
The most notable characteristic is its appearance when dry versus when wet. During periods of drought, the fronds shrivel, curl inward, and turn a grayish-brown, appearing dead. However, within hours of rainfall, the fronds uncurl and turn a vibrant green, springing back to life, which is the source of its common name. It thrives in moist environments, often found growing on tree trunks, rocks, and the large, textured limbs of live oak trees.
The Epiphytic Relationship with Host Trees
The primary reason the fern is not a threat to its host is its classification as an epiphyte, or “air plant.” This means the fern uses the tree purely for physical support, providing a stable surface to anchor itself and gain access to sunlight. The fern’s roots, which are actually long, creeping rhizomes, simply attach to the rough outer bark and do not penetrate the tree’s living vascular tissues like a parasite would.
Unlike parasitic plants, such as mistletoe, the Resurrection Fern does not derive nutrients or water from the tree’s internal systems. Instead, it collects all necessary moisture and minerals directly from the environment. Rainwater, airborne dust, and nutrients leaching from the surrounding bark are the fern’s sole sources of sustenance. This relationship is a harmless form of symbiosis, where the fern benefits from the host without causing it any damage.
The Science Behind Desiccation Tolerance
The fern’s ability to survive prolonged dry periods is rooted in desiccation tolerance. During a drought, the fronds shrivel and curl to minimize the surface area exposed to the elements, drastically reducing water loss. This mechanism allows the fern to lose an astonishing amount of its cellular water, often up to 75%, and in extreme drought conditions, as much as 97%, without suffering permanent damage.
In contrast, most other plants would perish if they lost more than 10% of their water content. The secret to the fern’s resilience lies in protective biochemicals, specifically specialized proteins and sugars like trehalose. These compounds stabilize the plant’s cell structures and prevent irreversible damage to cellular membranes during the severe dehydration process. Once water is reintroduced, the fern rapidly rehydrates, and its metabolic activity, including photosynthesis, resumes within a few hours.
Practical Implications for Tree Health
For a healthy, mature tree, the presence of the Resurrection Fern is benign, and removal is generally unnecessary. The fern thrives in areas where conditions are conducive to its growth, indicating adequate moisture and light, usually present on the large, horizontal limbs of trees like live oaks. The fern’s mats also create a beneficial microhabitat for small insects and fungi, contributing to the overall ecosystem.
The only potential, though rare, issues arise when the fern growth is exceptionally dense. A thick layer of any epiphyte can create excessive weight, which may contribute to limb failure during severe storms or high winds, especially on structurally unsound trees. Furthermore, a heavy blanket of ferns could block light from reaching the bark, but this rarely impacts the tree’s health since the bark is non-photosynthetic. Any noticeable tree decline is almost always attributable to underlying problems like disease, root damage, or pests, not the fern itself.