The Extreme Drought Tolerance Of The Resurrection Fern (Pleopeltis polypodioides)

Common Names: Resurrection Fern, Little Gray Polypod, Miracle Fern, Scaly Polypod
Scientific: Pleopeltis polypodioides
Synnomyns: Polypodium polypodioides
Family: POLYPODIACEAE

We tend to think of ferns as fairly water thirsty plants that are not at all capable of the extreme drought tolerance we more typically associate with cacti and other arid succulents. However the remarkable Resurrection Fern (Pleopeltis polypodioides) bucks this trend as it's the record holder for the plant which can survive the greatest length of time between watering. It has been estimated that this plant could potentially survive up to 100 years without water, however proving this estimate would be a painfully long, multi-generational study, unlikely to be economically feasible.

Pleopeltis polypodioides is a creeping epiphytic plant that grows on the bark of larger trees including oaks and cypress pines. Occasionally it can also be found growing on rotting logs and rocks. It's native range encompasses parts of the Americas, including a large chunk of the Southeastern United States and parts of Africa.

Being an epiphyte, the Resurrection Fern doesn't obtain nutrients from the soil. Instead the plant obtains the nutrients it requires to survive from the surrounding air and water it comes in contact with, as well as any nutrients on the surface of whatever the Resurrection Fern is attached to.

The leaves of the Resurrection Fern have a coarse texture, with each growing about 25 cm (10 inches) long by 5 cm (2 inches) wide. It uses a thin rhizome no thicker than 2mm in diameter to attach to and spread across the surface of the tree, log or rock it calls home.

As you may imagine, living as an epiphyte high up on a tree trunk is quite an exposed existence. As the surface is vertical, rainfall has little chance to sink in and any dampness the tree bark absorbs will quickly dry out. Many other epiphytes such as epiphytic orchids have water-storing succulent leaves to help them tolerate dry spells. The Resurrection Fern does things a little differently.

Pleopeltis polypodioides gained its common name of Resurrection Fern because following drought its curled up, dry, brown leaves can be revived to a plump green state in about a day with the tiniest amount of rain. When the leaves dry they curl up in such a way to maximise their ability to quickly re-hydrate after rain.

Most plants will die once they loose about 8-12% of their moisture. The Resurrection Fern can loose up to an amazing 97% of its moisture and still remain alive, although rarely do they loose more than about 76% in the wild before rainfall cause them to re-hydrate again.

This remarkable fern has one additional claim to fame. Nutty astronauts have taken dried Resurrection Ferns with them on a space shuttle mission just to see if they could resurrect themselves in the absence of gravity, fascinating stuff.