The item commonly sold as an “air fern” is a familiar household decoration, often presented in a small pot or terrarium. Its appeal lies in the fact that it appears to be a low-maintenance plant that thrives without soil, water, or sunlight. This popular name is highly misleading, as the delicate, fern-like structure is not a plant at all, nor is it alive, but rather the skeletal remains of a marine animal.
The True Identity: Not a Plant, But a Marine Animal
The decorative “air fern” is the preserved colony of a hydrozoan, a marine invertebrate classified in the phylum Cnidaria (which includes jellyfish and corals). The most common species used is Sertularia argentea, also known as sea fir or Neptune plant. What is displayed is the non-living, branching exoskeleton that once provided structure for a colony of tiny organisms.
This skeletal material is composed of chitin, a rigid, protein-like substance similar to the material found in the shells of insects and crustaceans. The bushy, fern-like appearance comes from the numerous small chambers, called hydrothecae, that once housed individual hydroid polyps. When alive, the colony lived attached to hard substrates on the seabed in the cooler waters of the North Atlantic Ocean.
The material is collected primarily as a byproduct of commercial trawling operations, particularly in the North Sea. Once harvested, the colonies are cleaned and dried for display. The specimens are frequently dyed a vibrant green to enhance their resemblance to a living houseplant, a practice that contributes to the product’s misconception.
Distinguishing the “Air Fern” from True Air Plants
The misnomer “air fern” often causes confusion with actual living organisms known as air plants. True air plants are species of Tillandsia, which belong to the Bromeliad family (the same group as the pineapple). These are epiphytes, meaning they naturally grow by attaching themselves to other plants, such as tree branches, without drawing nutrients from their host.
The Tillandsia air plant is a photosynthesizing organism that requires regular moisture and light to survive. It absorbs water and nutrients through specialized scales on its leaves called trichomes, rather than through its small, anchoring roots. Maintenance involves soaking or misting the entire plant regularly, typically once a week, along with providing bright, indirect sunlight.
In contrast, the decorative hydrozoan skeleton is non-living and requires the exact opposite care regimen. It does not photosynthesize, will never grow, and cannot be revived with water. The fundamental difference is that one is a living plant capable of growth, while the other is the dried remains of a colonial animal.
Maintenance of the Decorative Display
Since the “air fern” is not a living organism, care focuses entirely on maintaining its aesthetic appearance and preventing damage. The primary concern for these brittle, dried skeletons is the accumulation of dust, which is challenging to remove from the delicate, fine branches. The safest cleaning method involves using a soft feather duster or gently blowing the dust away with a low-speed, cool-setting hairdryer.
Rough handling or attempting to wipe the surface with a cloth should be avoided, as the fine, chitinous structure can easily break or crumble. Exposure to moisture, such as placing the item in a humid bathroom or kitchen, is detrimental. High humidity can cause the material to soften, potentially leading to mold development or causing the color to bleed or run if the skeleton was dyed.
The dyes used to color the specimen are also susceptible to fading when exposed to intense light. Therefore, the item should be displayed away from direct, harsh sunlight to prevent the green coloration from bleaching out over time.