The varied lifestyles of epiphytes

Epiphytes are, by definition, plants that grow on other plants, but like many aspects of the natural world, they don't quite fit within this box.

Species that most commonly grow on trees can also be found in many other habitat types in New Zealand. Here are some examples:

Tawhiri karo (Pittosporum cornifolium) growing on limestone. Photo: C. Kirby.

Raurenga (Cardiomanes reniforme), kowaowao (Microsorum pustulatum) and filmy ferns (Hymenophyllum species) growing on volcanic scoria. Photo: C. Kirby.

Yes, the kowaowao here is growing on another plant but in the frond bases - not on the trunk or branches... a little different. Photo: C. Kirby.

Puka (Griselinia lucida) growing in a thin soil profile on a small island. Photo: C. Kirby.

Maybe a better definition of an epiphyte is a plant that can handle dessication, wind and fluctuating temperatures? They are very hardy plants and have a range of features that help them survive in harsh conditions. This new definition seems to work for these tough characters:

Peperomia growing in a crack of a rock outcrop. Photo: C. Kirby.

Kirk’s kohuhu (Pittosporum kirkii) growing on a cliff. Photo: C. Kirby.

Kowaowao climbing up a rock. Photo: C. Kirby.

There are other terms that can describe these different lifestyles: a "saxicole" is a plant that grows on rocks and a "halophyte" is a plant that can handle exposure to salt water but maybe these species are best described as "hardy opportunists"? Inhabiting these harsh environments presents an opportunity to thrive and reproduce where other species can't.