How to Be an Invasive Exotic, Lygodium microphyllum Style

This is Old World climbing fern. It is an invasive exotic plant, and this is what it does best.

Those trees on the left are what trees are supposed to look like, all tree shaped and growing normally. Those trees on the right… wait, what’s that you say? You can’t see the trees? Oh yeah. That’s because they are covered in strings upon strings of fern that are intently keen on smothering anything and everything on their way towards the light.

Lygodium microphyllum. The life cycle of Lygodium is really neat. It’s not from around here (hence the “exotic” part), and is really, really good at spreading (thus, “invasive”). As a fern, it follows the typical “really likes wet areas” theme, and is complete with the cute little sorus collections on the underside of the fertile leaves that produce thousands upon thousands of spores. Per leaf. These spores, and the climbing nature of this particular fern, are what make it so prolific. You can see the little dots in some of these pictures. Those are the collections of things that contain the thousands of spores, not the spores themselves.

Seeds? Seeds?! They don’t need no stinking seeds. Want to reproduce? Just throw a bunch of spores out to the wind, hope some land in a nice damp bayhead (and a lot of them do), then just jump through a few fancy growth stages, and continue your growth back up towards the light. Not all of the leaves have these structures. You can see the two leaf types in the pictures below, some are vegetative, but some are just waiting to release their children. That means that when you pull at the vines to cut them, some times the spores get tossed to the breeze.

As this cycle of spore to vine is actually pretty quick, the plants unlucky enough to be the climbees, as opposed to the climbers, may not even have had time enough to die before being completely enveloped in fern. Armed with herbicide, clippers, and soon a machete (to better grapple with the ever present blackberry bushes), I have been tasked to go around and attempt to free these trees and kill as much climbing fern as possible to prevent further spread. Our goal is to cut any vine that is taller than waist high, and herbicide everything below.