confronting vegetation: Pteridium

The attraction of New Caledonia, for me and especially for my biologist friend Phil Gleeson, is its vast and bizarre array of endemic plants -- species of plants that are found nowhere else. So I treasure the irony that it's here, for the first time, that I really started to look at one of the most widespread plants on the planet.

Bracken fern (Pteridium) is cosmopolitan in the beautiful scientific sense of that word: it's found on every continent except Antarctica, in a vast range of climates and situations.  (Cosmopolitan is more or less the opposite of endemic, which means found only in one place.  Endemism -- lots of plants you won't see anywhere else -- is what biologists like Phil and dilettantish plant-lovers like me go to New Caledonia for.)  

For a while, all Pteridium were thought to be a single species, which would have made it by far the world's most widespread plant.  So it's not surprising that in its very ordinariness, it stands out from New Caledonia's crowd of unique personalities.

I noticed it because of how it dies.

In New Caledonia at least, dying bracken (in the sense of dying back to the surface, which is a normal part of life for this perennial fern) goes through four very distinct phases.  First it's green, then it turns black, then light brown, and finally a silvery white. 

At the end of this process, the shriveled plant is oddly evocative of a cow skull.

Why is New Caledonia's dead bracken white, almost silver? A Wikipedia photo from the Maritime provinces of Canada supports my faint recollection that in the Northern Hemisphere, dying bracken is mostly brown.  (Is that true where you are?  Go have a look; there's probably some bracken near your house.  And is it only New Caledonia's bracken that goes through four color phases in the course of dying?)

To aggravate my scientist friend Phil, I might speculate that dead bracken is so intensely white here because brown wouldn't look so good against the red-brown soil that dominates this part of New Caledonia; in, short, if one could believe in intelligent design, we could praise the designer's good eye for contrasts in color.

For that matter, why is nature beautiful at all?  When in our evolutionary history did one of us discover that the world is beautiful, and why did that confer an advantage on the bottom line of survival and reproduction?

Comments

[Teresa Gilman]

OK, Jarrett, now I'm going to grab the nearest dog and go out bracken sighting this weekend. I'll let you know how it's dying here, and the colors. But if you're going to get all existential on us, go read some Nathalie Angier, and she'll stir up your wondering about beauty at all, and why, and why not.

Your photos are lovely.

Teresa

[Peter]

Beautiful post.

I know nothing about dying bracken, but there's nothing around here that looks that white dead, unless it died by fire.

[Philip Gleeson]

I'm not sure that you really understand what aggravates me. I simply reject that there are scientific theories that are distinct from aesthetic theories. There are only truth claims, statements that claim to represent a reality about the world. There is nothing wrong with making a claim that bracken might be white to look good against the orange soil. However, to do so, you must then posit a being or process that is doing the choosing and has aesthetic opinions. If you wish to infer an intelligent designer then that is your prerogative, but that leaves a lot more unexplained than it purports to answer.

I think the question about beauty is a far more interesting one, and one that has occupied many minds. The important point to note, as you have, is that beauty is in the eye of the beholder, so the question is really why do we find nature beautiful, rather than why is nature beautiful. It's easy to find evolutionary explanations for why we find particular faces or bodies beautiful. Is our appreciation of the beauty of nature just an extension of that process or something different?

[Jarrett]

Teresa and Peter. Thanks for these comments. I look forward to further reports from the field.

Phil. Exactly. We don't disagree at all, except on the matter of truth claims. All sentences beginning "I might speculate ..." are trivially true, and this truth is obviously not the point. The purpose of such statements is to conjure the imagination rather than assert a claim about the world.

[Dave]

Bracken here turns pale yellow at first, then brown. Nothing like in these striking photos of yours.

[Ms. P]

Lovely post, and delightful blog. (Found you through pronoia)

[Teresa Gilman]

[sigh!] I've yet to find the dying bracken, though I've gone out twice with that intent. It's either that I've got distracted by the more vivid colors now present [see my latest post] or else there is no bracken where I've gone.

But, good scientist that I am, I won't give up.

T.

[Jarrett]

Thanks, Teresa! If you didn't notice the dead bracken, it probably wasn't that interesting. I've since looked at dead bracken in Australia, and it's brown as well. The silver-white quality of New Caledonian death remains a mystery and a fascination.