Phlebodium aureum

(Phlebodium refers to veins, as does the medical condition Phlebitis. Aureum means golden. Polypody means “many feet,” referring to the fuzzy stems.)

Polypodiaceae

Take a look at a Cabbage Palm in the woods or in a yard.  Chances are it hosts a Golden Polypody fern hanging out of the old dead leaf bases, or even among green ones up top. 

As plant perched up on another plant, Golden Polypody pushes the envelope on the term “epiphyte.”  Its massive snakelike stem burrows intimately among the leaf bases.   It does not pull free easily, and then there are mycorrhizae.  Mycorrhizae are fungi embedded in plant roots, one end in the root, the other engaged in decaying organic matter, sending a share to the fern root.  Where are those Golden Polypody mycorrhizae going?   There’s no evidence the fern and its fungal friends penetrate into the living tissue of the palm, or cause it any harm.   Still, if you used radioactive fertilizer on the palm, would radioactivity turn up in the fern?    Funny—come to think of it—-some fertilizer can be a teensie tiny bit radioactive.

What’s known slightly better is the ability of Phlebodium ferns to suppress competitors.  There you are, a fern growing on a palm trunk.  Wouldn‘t it be convenient to poison other ferns, mosses, vines, and competitors who would like to share the palm trunk?   If you look at a lot of palms with Golden Polypodys you might conclude that they do seem surprisingly free of competing trunk-dwellers.   Hard to certain about that, but the ability has been lab-tested.   Interestingly, the fern suppresses other plants only when the fern leaves are present.   Other ferns can stifle Golden Polypody too, it is warfare! Much more study needed.  Speaking of chemo-warfare, the fern also produces a false insect hormone, polypodoaurein, no doubt to confuddle buggies who cause the fern distress.

The truly odd thing about Golden Polypody  is that it is really two species for the price of one.  This fern is a perfect example of something that is not rare in the plant world:   it has not the normal two sets of chromosomes,  but rather four sets, two from a species called Phlebodium pseudoaureum and two from Phlebodium decumanum, both of these native to Tropical America, not Florida.    (It may be a useful reminder that you and I have two sets of chromosomes, one set from your mother and one from your father. Whem mommies and daddies make a baby the baby does NOT have four sets of chromosomes.) ((Unless it is Phlebodium aureum.))

Now then, isn’t that something—-neither of the parental fern species live in the U.S. but when the two are combined into Phlebodium aureum,  it can live all the way to Georgia.    Although not studied adequately to be sure of the full situation, and for reasons I don’t want to attempt to explain in a short blog,  the two-species-in-one Phlebodium aureum is self-fertile, giving it the ability to colonize new places, such as Florida.   Come to think of it, on a much smaller scale, self-fertility is handy for a fern living isolated on a tree trunk.

Does Phlebodium aureum live together with its two “parent” species?   Yes, in Puerto Rico Phlebodium aureum (with its four sets of chromosomes) crosses with its “parent” species, each with two sets of chromosomes, the offspring having, you guessed it, three sets of chromosomes.