Friday, 6 March 2015

Remarkable resurrection ferns

Resurrection ferns dried and hydrated.

Resurrection fern (Pleopeltis polypodioides)


While I'd seen spare populations of resurrection ferns when I lived in Maryland, I really became aware of them when I read "Light a Distant Fire," an historic novel about Osceola and the Seminoles by Lucia St. Clair Robson. She wrote about how the scouts could disappear into the ferns on the live oak branches. After we moved to Florida, I came to see how this could be accomplished.

This is a true fern that reproduces via spores, but it is also an epiphyte or air plant. It does not need to be in contact with soil to live. It derives its needs from the air, especially the humidity and dust that it carries.

The common name of resurrection fern is due to its ability to lose 95% of its moisture, stop its photosynthesis, and go into a type of suspended state when it appears to be dead. When it rains or when the humidity becomes high enough, the fronds unfurl and turn green in a matter of hours. Hence the name resurrection fern, because it arises from the dead.

Most other plants will die if they lose 10 to 15% of their water. Scientists have discovered that this fern has a high concentration of a special protein (dehydrin) in or near its cell walls when it is brown. When the fern is green this protein is not present indicating a chemical reaction as the water exits the cells.  In other words as the plant is drying, dehydrin allows the cell walls in the leaf to fold so that the unfolding when water is present can be reversed without damage. For the science of dehydrin see this paper in The American Journal of Botany.

Steve Christman over on Floridata.com states that you can propagate these ferns by laying pieces of the rhizome into the furrows of the bark of the tree where you want to grow it. I may try this one day, because I'd love to have more of them around on our property. On the other hand, I can wait for Mother Nature to plant them in appropriate places without doing any work.

But whatever the science, these small ferns add to the charm of Florida's live oaks. 

In their normal habitat: horizontal branches of a live oak (Quercus verginiana).

This is in South Florida in the wet season, but the ferns are turning brown around the edges.

The fern looks dead, but it's not...
After reading this post, go drink some water, because humans will die when we lose only 15% of our water. Also, full disclosure: Lucia and I are good friends and were neighbors in Maryland where she still lives and where she has written a bunch of fun-to-read and well-researched historicals. She was a librarian and knows how to make her readers feel like full participants in the story. www.luciastclairrobson.com

Green Gardening Matters,
Ginny Stibolt

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