You Can’t Keep a Good Fern Down

23 Jun

Small Leaf Climbing Fern

Lygodium microphyllum

(Lygodium means flexible. Microphyllum means small leaf)



This morning John and I pursued minor projects in Kiplinger Wildlife Preserve, in awe of the imperialistic Small Leaf Climbing Fern,  a gift that keeps on giving from the Old World, first recorded in Florida during Elvis, escaped during the Beatles.

Lygodium microphyllum 1

Going up!   By John Bradford.

Its massive growth is matched by  massive attention to its peskiness on the Internet. No need to be the millionth post on that.  For those unfamiliar with the problem, probably not Florida residents, this fern can smother a tree in the wink of an eye, climb high into the canopy, spread fires, and even reportedly snare a deer.

Lygodium microphyllum 5

Spore-bearing leaflets. By JB

Rather than rant on about invasiveness, it might be more interesting to explore the biology of this super-weed.  Two invasive Lygodiums compete to own Florida:  Lygodium microphyllum is  common around Palm Beach County.  Lygodium japonicum is more prevalent northward.   Farther north still across the Florida state line comes the native Lygodium palmatum.  The invasive species grow like lightning, L japonicum as much as three inches a day.

Lygodium frond segment

Leaflets along a small stretch of one long rising leaf.

These clambering vines are not really vines.  The entire aboveground  climber is a leaf, a frond, although division into leaflets along a stringy center gives the false appearance of a leafy stem.    But no.  The true stem is at or below ground level,  launching the immortal ever-lengthening leaves skyward to go forth and multiply.    The individual leaves climb 30 feet or more.

And here is how:    The tip of most any fern leaf (frond) is a curl called a crozier.   Normally the crozier uncurls, and that’s that.  But this is no normal fern.  In Lygodium the crozier never uncurls.  It just keeps on lengthening the leaf.    The leaf portion behind the crozier stays bare like a thin twig and forms a hook.  The hook rotates on its own, and also blows in the wind.   All this twistin’, and hookin’; and blowin’ is an effort to hook onto something to climb.   When that happens, let the rise ensue until the leaf snakes to the top of the host, then the hooky business resumes seeking a taller host.  Upsie daisy!  Below the hooky region the older regions broaden out into the characteristic leaflets,  hundreds of them like lights bulbs strung on a wire around a used car lot.

Lygodium microphyllum crozier

Climbing Fern crozier

If a leaf extends high up into the tree and then breaks off, oh my, what a disaster.  But no, wait, there is a safety mechanism.  Along the leaf are fuzzy rust-colored buds ready to grow forth and save the day.

That the leaves rise directly from the “roots” allows direct immediate nutrient interchange between leaf and “root.”   Such efficient root-leaf commerce has turned out, it seems, to allow for especially enriched roots to cope with bad soil, not to mention fuel that magical leaf growth.

Lygodium microphyllum stem tip region

Hooked leaf tip, crozier at the very end.

Botanists have shown…at least under some circumstances…the plants to grow equally well in bright sun and deep shade.  They do not care.   Wet places are favorite habitats, pine woods will do, and even sometimes dry scrub.    It’s all good!   Flooding seems to boost spore production, and that is a deliberate segue:

Ferns reproduce by dust-sized spores blowing in the wind.  One individual Climbing Fern can produce astronomical numbers of spores.  There has been concern that workers exterminating the fern get their clothes contaminated with spores, spreading the pest unwittingly, helping it rather than wiping it out.

Lygodium microphyllum bud

Fuzzy bud on leaf.

Watch the hook helped by wind seek a new host to climb:   CLICK

When the baby Climbing Fern  grows from the spore it matures as female with a trick. She releases hormones to make the  nearby babies mature male as automatic mates.

If that fails, the female develops its own sperm-producing organs and fertilizers itself.

There’s no stopping Climbing Fern.

Lygodium microphyllum being sprayed by John Lampkin with permission

Photo courtesy of John Lampkin.


Posted by on June 23, 2017 in Uncategorized


5 responses to “You Can’t Keep a Good Fern Down

  1. Chris Lockhart

    June 23, 2017 at 10:23 pm

    I love the tongue in cheek description of OWCF as a ‘good’ fern. BTW, Japanese climbing fern has jumped to Palm Beach County now and then. Sometimes tougher to treat due to a thicker root system (more storage capacity, perhaps?). they’re both wiry, so come armed with pruning shears or a blade! As of a few years ago, their distributions overlapped in 16 counties. I think OWCF has gotten as far north as Volusia County and kept at bay. What a pesky fern it is!! Kill it!! but cut all the wiry stems or it will be back in little time. 🙂

  2. FlowerAlley

    June 24, 2017 at 9:14 am

    Fascinating reporting.

    • George Rogers

      June 24, 2017 at 9:41 am

      Chris, You know of any definite and accessible Japanese CF near Jupiter? There was a patch along the St. Lucie River but it got “taken care of.” Also herbarium sheets from some in Jupiter Farms I can’t find, probably eradicated, and some down near Lion Country Safari probably also sprayed away by now. I’m looking for some easy to get to for photos.

    • George Rogers

      June 24, 2017 at 9:41 am

      Thanks Flower Alley…you tend to deal usually with more attractive species nobody wants to spray.

  3. theshrubqueen

    June 24, 2017 at 3:45 pm

    Used to plant JCF in Atlanta as an ornamental. Hard to get started!


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