Excerpts from Jim Conrad's
from the October 6, 2006 Newsletter, written near Natchez, Mississippi, USA
JAPANESE CLIMBING FERNS ON THE MARCH
I have the same question with regard to Japanese Climbing Ferns, LYGODIUM JAPONICUM. They've been here for some years, but my impression is that their numbers now are drastically increasing.
You can see a roadcut passed by during my walk practically overgrown with Japanese Climbing Fern at the right.
In that picture, for scale, notice the goldenrods and no-trespassing sign at the top.
You can see a close-up of the much-dissected frond below.
Japanese Climbing Ferns are an invasive species introduced from eastern Asia and Australia. If you view the above roadcut picture you'll have no trouble accepting that it can smother out native ground cover and tree seedlings.
Still, it's a fascinating plant. First, it is indeed a vine, and you know that ferns aren't generally vines. Second, as I wrote in my February 23rd, 2003 Newsletter, "its anatomy is simply outrageous. What looks like the vine's wiry stem is actually a single climbing, freely branching, leaf (frond) as much as 100 feet long (30 m). What appears to be fronds arising from the stem are actually subdivisions of a single super-long frond."