Thursday, November 8, 2012

Selaginella

I often post about non-ferns here, especially if I have particularly nice flowering plant photos I'd like to share, but today we shift to another lineage entirely: the often overlooked lycophytes! Lycophytes used to be called "fern allies" because the relationships between these two and the other groups of land plants weren't well understood. Now we know that lycophytes are the sister group to ferns plus angiosperms and gymnosperms, meaning that ferns are more closely related to conifers and flowering plants than they are to lycophytes. Lycophytes are equally related to all three, because they share a common ancestor with all of those three groups, before their three lineages diverged. Here's a family tree of the major land plant lineages that might clarify things:


(UPDATE, 8/6/13: Since posting this phylogeny figure over a year and a half ago, I've seen several colleagues use it in talks. I'm tickled by this, but it has also made me uneasy about the lack of attribution here for the images I used in the figure. I scavenged all seven of the images from the internet, and at this distance I've been unable to relocate the liverwort, hornwort, and lycophyte drawings; I think I recall that they are old enough to be in the public domain. Here is all the information I have about each of the other drawings and where I found them, and I am grateful to all of these artists for their wonderful work. Mosses: Moss, Watercolor, by Maria Alice De Rezende, BrazilFerns: Polypodium vulgare, Illustration from Scandinavian Ferns by Benjamin ├śllgaard and Kirsten Tind, Rhodos, 1993Gymnosperms: Pseudotsuga menziesi, by Brigid Edwards, Shirley Sherwood CollectionAngiosperms: Clematis 'Cezanne', watercolor, Karla Beatty.)

On our field trip to Organ Pipe a few weeks ago, we were after lycophytes, particularly members of the genus Selaginella. These are often called "resurrection plants" because of their ability to dry down when water becomes scarce and then rapidly rehydrate when the rains return. Here's a great video, made by a fern colleague, Fernando Matos, showing a Selaginella "coming back to life":


The ones that we found haven't quite gotten to resurrecting yet... it's pretty dry out there right now. You might not notice them at first, because they're quite diminutive and rather crinkly and dried up, but once you know what to look for, you'll find that you're surrounded by a carpet of Selaginella in many of the rocky, desert-y areas around here. The lower photos here demonstrate that:






This is the type of habitat we found these guys in, rocky upslope and surrounded by various grasses, cacti, cholla, and other typical desert plants:




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3 comments:

Susan said...

Your phylogeny is mislabeled; hornworts and liverworts need to be switched (pictures are correct).

Emily said...

Eep! Thanks Susan! They got flipped around when I was label-making in Illustrator :) Thanks for the catch! I've updated the figure in the post and it's now correct.

The Phytophactor said...

Selaginella - oldest living genus of vascular plants; now that's pretty cool.