Monday, April 1, 2024

A ferny tale (Marsilea macropoda mystery solved)

Marsilea macropoda in Wildflower Treasures
    This is not really an April Fool's post--although a fern that looks like a four leaf clover is certainly a novelty. I can't remember who first brought this--I am sure it was from Texas--but we planted it here and there at Denver Botanic Gardens (and I have a thrifty colony at my house). The colony above no longer exists, the Wildflower Treasures is now a veggie plot. I somehow doubt the ferns were rescued when the site was bulldozed. And come to think of it, what happened to all that flagstone?

Marsilea macropoda range map in BONAP

How could a plant with such a southerly distribution be such a toughie? It took a bulldozer to get rid of that colony. It thrives for me between paving stones next to the pond at our home--where it alternately drowns and bakes and freezes and cooks.

A slightly larger image of the plant--an herbarium specimen from Texas, where our original plant came from--I recall someone telling me that it grew gloriously, making a solid mat in a bed in front of the entrance of San Antonio Botanical Garden.

That factoid swam around in my head for many decades: at least three. I kept it there, no doubt, hoping one day to finally visit that garden (a fine garden, incidentally: I should do a blog post about it...but it would be long and this story is mercifully short).

A long time ago, someone (who are all these people anyway?) told me the fern had been removed from that bed: I can't recall who, but this factoid joined the other one....and last Tuesday, I finally got to SABG with Tom Peace and Patrick Kirwin--two terrific plantsmen and friends. I was recounting pretty much everything I've just told you as we walked towards the entrance gate.  

As I was wrapping up my tale of woe to my friends, Tom spied this label in the bed where the fern once putatively grew. Factoid one and two appear to both have been correct! Hallelujah--perhaps now I can free up that brain space for new factoids.

In the interest of fairness and accuracy, there were two tufts of Bigfoot Water Clover ACROSS the wide sidewalk from the putative bed where the label was. Perhaps THAT was the bed were they once grew and now have largely disappeared? And the label somehow crossed the path?

But many new and more pressing factoids are starting to crop up...

Marsilea vestita

Here is the BONAP range map for Marsilea vestita: much more common and widespread than M. macropoda. As you can see from the image below, it certainly resembles our putative plant...

How similar are the two species? Since M. vestita is so widespread, why have I never seen it? How does it compare to M. macropoda

One mystery solved, a lot more mysteries are emerging!

In any case, I'm grateful to have resolved at least a few long standing questions. How many lingering mysteries are rattling around in your brain?


  1. I am surprised Marsilea would grow in what looks like dry gravel.

    A reason you might not have come across Marsilea before is not spending time in wetlands.

  2. The spot where that Marsilea grew in Wildflower treasures, James, was irrigated regularly (the troughs were mostly alpines and needed regular watering) so I doubt the fern ever dried out much. But I've found it to be incredibly adaptable--there's a clump growing in the largely UNWATERED APEX crevice garden--at the base of a rock, on a northern exposure to be sure. This is one fabulous groundcover: I don't know a single commercial source now that Laporte Alpines stopped selling mailorder.


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