Epiphytes: Air Plants & More

Ball moss is a common epiphyte & is typical
of what most people imagine when they
think "air plant." It attaches itself to a tree
& spends its life there.
 

Epiphyte derives from Greek epi- 'upon' and phyton 'plant'. An epiphyte is a non-parasitic, organism that grows on a plant and that derives moisture & nutrition from its surrounding ecosystem. Most people associate this with the terrestrial epiphytes or "air plants" that make their living without touching the ground, but wait, there's more...

Terrestrial epiphytes

Terrestrial epiphytes are plentiful where there is frequent rain or fog such as rain forests (both tropical and temperate) and also areas like Florida, especially near wetlands, but some epiphytes are also found in drier areas. They could be vascular flowering plants such as orchids, cacti, or bromeliads including ball moss & Spanish moss. They include vascular spore-producing plants such as ferns. Almost 10% of vascular plants are epiphytic.  Non-vascular, spore-producing plants such as mosses and club mosses are frequently epiphytes. 

Since epiphytic life can be precarious, many of these plants have fine hairs or waxy surfaces to trap or keep water. Some collect water in-between their leaves, but others have adapted to water shortages by using the CAM or C4 method of photosynthesis that can take place even when all their stomata (leaf pores) are closed to conserve water.

Lichens, which are not plants, but 3-way symbiotic organisms (fungi, algae, & bacteria), are also epiphytes when attached to plants. 

Strangler figs (Ficus spp.) are a special case: they are hemi-epiphytes when they begin life as a epiphyte high in the canopy, but when their aerial roots reach the ground, they are no longer epiphytes. It's a clever strategy, especially in rain forests where there is low light on the ground and the canopy is crowded. It's in the light when its young and it often takes over its host's spot in the canopy after strangling it by wrapping its roots around it.
(See below for more on terrestrial epiphytes.)

These barnacles, sessile animals (crustaceans),
attached to a kelp stipe (stem above the holdfast),
are marine epiphytes. 

Marine epiphytes

In the marine environment, plants, such as non-vascular seaweeds and vascular, flowering seagrasses, provide surfaces where sessile organisms can settle. Marine epiphytes include algae (micro & macro), bacteria, sponges, bryozoans, ascidians, protozoa, hydroids, crustaceans, & mollusks. They make their living from the nutrients and oxygen from the surrounding water, not from the plants. Sometimes, when there are too many epiphytes, the host plant may suffer from lack of light or lack of its own gas exchange.

 

Epiphytes in Florida

The "Real Florida" forests include a wide variety of epiphytes. In this Central Florida preserve,
southern live oaks (Quercus virginiana) support resurrection ferns, Spanish Moss, ball moss, & more.

This classic Corkscrew Swamp photo by Audubon shows the prevalence of epiphytes on ancient bald cypress trees (Taxodium distichum) growing in standing water. 

This strangler fig (Ficus aurea) at Corkscrew Swamp started its life high in its host tree as an epiphyte, but now that its aerial roots have reached the ground, it's no longer an epiphyte.

Lichens are not plants but 3-way symbiotic organisms. They are epiphytes when attached to trees or other plants, but not when they are attached to rocks or other substrates.

Spanish moss (Tillandsia usneoides) is a flowering plant in the bromeliad family. While not sessile, it's an epiphyte when it's draped on tree branches. It cleans the air, produces oxygen, supports pollinators, & does not need to be removed from your trees. (The red fruit in this January photo are maple seeds.)

The cardinal air plant
 (Tillandsia fasciculata) has a large showy flower, unlike its relative Spanish moss (T. usneoides) that has flowers so tiny that most people have never seen them. 

This collection of epiphytes on tree bark includes resurrection ferns, ball moss, & lichens.

The ghost orchid (Dendrophylax lindenii) is a rare epiphytic orchid native to Florida, Cuba, & a few other Caribbean islands. Photo from Corkscrew Audubon. 

The presence of epiphytes in an ecosystem proves the resilience of Nature to make the best use of space in ways that we can only superficially understand. 

References:
- Remarkable resurrection ferns 
- There's nothing Spanish or mossy about Spanish moss 
- Lichen: a three-way symbiotic organism 

- CAM/64 photosynthesis in epiphytes
- Learn more about the C4 method of photosynthesis here: The science behind southern grasses
- Science direct on epiphytes

Green Gardening Matters,
Ginny Stibolt