Excerpts from Jim Conrad's
Naturalist Newsletter

Calaguala or Samambaia fern, PHLEBODIUM DECUMANUM

from the March 4, 2012 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO

In an abandoned lot on a backstreet of Dzitas, several Huano Thatch Palms cast cool, pleasing shade. On Huano trunks, the stiff petioles of old fronds remain long after the fronds have broken off, making the trunks look bristly and raggedy. Over time, organic and inorganic detritus collects in the angles between the old petioles and the trunks, forming a kind of soil. Plants can root in that airborne palm-trunk soil, animals can take up residence there, and other organisms can come to create whole palm-trunk ecosystems.

On this particular backstreet in Dzitas, most older Huano palm-trunk ecosystems hosted a fern species I've not seen elsewhere in the Yucatán, as shown at the top of this page.

Luckily, several frond segments bore spore-producing sori, or "fruit dots," needed for identification, seen below:

Calaguala or Samambaia fern, PHLEBODIUM DECUMANUM, sori

Not many kinds of ferns have their sori scattered across their fronds' broad undersurfaces like that. Among ferns up North the only ones with sori looking a little like this are the Polypodies, genus Polypodium. In fact, our Huano-trunk fern species has sometimes been placed in the genus Polypodium, but nowadays most experts assign it to Phlebodium -- it's PHLEBODIUM DECUMANUM.

And that's interesting because I don't find Phlebodium decumanum listed for the Yucatán. It occurs from southern Mexico south deep into South America, but I am surprised to find it growing under such relatively arid conditions as here.

Finding Phlebodium decumanum here also is interesting because its fronds and rhizomes are regarded by many as medicinal. However, there's little agreement about what they're medicinal for. You can find claims that they're good for everything from whooping cough and fever to joint pain, blood needing cleansing, dermatitis, problems of the pancreas... on and on.

But, maybe there's something to the claims. Clinical research involving various double-blind placebo human trials found that a water extract from the fern was "an effective treatment for psoriasis --as well as dermatitis and vitiligo (with a 3-6 month course of treatment required)."

A common Spanish name for the fern is Calaguala. In Brazil they call it Samambaia. Medicines based on the fern are often marketed under those names.