Thursday, November 1, 2012

Desert ferns

Finally, some fern sightings here in the desert! These come to you courtesy of Organ Pipe National Monument, located in the far southwestern corner of Arizona. I took a field trip there with my lab last week, in search of Selaginella (which will be the focus of my next post), and we also came across two ferns growing cheek-by-jowl with those little lycophytes. My desert fern ID skills are not (yet!) great, so these might be off. If anyone recognizes either of these, please leave a note in the comments. 

First up we have an Astrolepis species, possibly A. cochisensis:

 And next we have, I'm pretty sure, Notholaena standleyi:

These guys may not look like much, but they are doing exactly what ferns (or any plants, for that matter) in the desert should be doing: trying to conserve water. They are xerophytes, plants that are adapted to places where there is very little moisture. And they are nicely demonstrating several of the adaptations that ferns around here have for dealing with this. For example, the Astrolepis is quite furry, and those little hairs serve two purposes: they shade the leaf a bit, and they help trap any moisture that becomes available, from rain, dew, or a particularly humid day. The Notholaena is employing a different strategy. It has curled up, reducing surface area, and is probably dormant and waiting for the next rains to arrive. Other desert ferns have farina, a waxy or grainy covering on one or both leaf surfaces that reflects light and prevents evaporation. 

There are some nice resources available online if you're interested in cultivating or identifying desert ferns, or learning more about their xerophytic adaptations. There's a nice list of southern Arizona ferns, complete with illustrations, and from the same source, a page about desert fern adaptations.

Finally, here are some views of the lovely Organ Pipe terrain around where we found these ferns... and of course the eponymous cactus itself:

1 comment:

Jake Dyer said...

Organ Pipe is awesome! Pretty amazing vegetation in the Sonoran Desert... Just found your blog today and I love it! I am not a fern expert, however, I am a 'green things' enthusiast! Look forward to more posts!

-Jake Dyer

P.S. We had Tom Givnish's class together back in 08 I believe? I was in the forestry department. Anwyays, good to see you doing well!