Sunday, March 05, 2006

Toward Burning Bushes

Running home the other night, up the long hill to our house, I wondered: Why do plants not glow (or glow more often) in nature? We can engineer them to glow, granted. But I’ve found no example of a naturally-occurring plant that glows.

Why my surprise? Because I should think that plants might reproduce more efficiently if they could attract night pollinators with glowing flowers. I would thus have expected glowing plants to evolve, and to occur naturally with unsurprising frequency. Perhaps I underestimate the energy required to phosphoresce; perhaps plants rely on pollinators' sense of small rather than of sight for good reason. But wouldn't the same calculations counsel against glowing in animals?

At any rate, I look forward to seeing more of bioengineered phosphorescent plants. Some people in my neighborhood like to light up their landscaping at night. I cannot deny the aesthetic impact of a nice lighting job, yet I rue the waste. Surely it would prove more economical to let your landscaping provide its own light. And wouldn’t you enjoy walking up to your front door under a canopy of twinkling flowers? Or the pillars of illuminating palms? Coo-ell.


philippe de backer said...

Here are some reasons why I think plants don't exhibit bioluminescence to my knowledge

The reaction to make things glow in nature is very energy expensive. It costs ATP, the energy source of a lot of reactions in the cell, both for plants and animals.

Also, insects often see in the ultraviolet spectrum. You often see that the appearance of flowers drastically changes when we look at a flower not under "normal light" (what we can see), but under ultraviolet light.

A bioluminiscence reaction often emmits light in the green spectra, so it would be useless to insects, because they can't see it.

Night pollinators often find their way to flowers through scent. That is why most night bloomers often have a strong scent.

But I agree with you that it would be cool. I worked in the lab for a year with fluorescent plants, and it is a cool gift for you girlfriend...

Jeff Brown said...

I didn't know insects can't see bioluminescence! That's cool.

I was going to say that my guess is that the benefits of bioluminescence to plants must be low, because the cost doesn't seem prohibitive -- surely some plants (e.g. cacti) receive more energy than they use.

Tom W. Bell said...

Interesting and informative comments, Phillipe! Thanks.

Good point about cacti and other succulents, Jeff.

By the way, rereading my post, I see I might have clarified the obvious: When I spoke of plants relying on smell more than sight, I was of course referring to how they lure pollintors at night.

Mizz bee said...

Why flowers don't glow in the dark? What an interesting mental exercise! In addition to the other arguments presented, I think that they don't glow for the same reason that female moths don't glow either, the males can locate them by smell alone, miles away; so, they can do the same thing about flowers, I suppose, and most nocturnal pollinators are moths.