Creosote Bush...

The creosote bush (Larrea tridentata) is not a plant that excites most people. It's the most common shrub in our desert, generally looks pretty ratty, has small and inconspicuous flowers that don't smell good, and little tiny green leaves that leave an oily smear on your fingers or clothes if you brush up against it. If you crush the leaves, it smells vaguely of creosote. I'd read that if you create some humid air around its leaves by cupping your hands around a twig and blowing into them, you'll smell the wonderful aroma of rain on the desert. I tried it, and I think people are smoking something they shouldn't oughtta be – smells like a combination of stale breath and creosote to me.

But there really are some interesting things about the creosote bush. For starters, the individual plants live a very long time for a shrub: 100 to 200 years, possibly more. They produce lots and lots of seeds, but the germination rate is very low. Most of the individual plants are actually clones. It works like this: a single ancestral plant germinates from windblown or bird-carried seed, far from any other creosote bushes. That plant grows for a hundred years or so, gradually increasing in diameter, with the younger shoots on the outside.

Eventually the inner, older shoots die off, leaving a ring-shaped shrub. These are rare, but they do exist – I've seen four or five over the years. These rings gradually increase in size by the same mechanism, until (I've read) they are something like 20 to 50 feet in diameter. The biggest one I've ever seen was only about 6 feet in diameter, with about a 4 foot in diameter “dead zone” in the middle.

The scarcest resource for these plants is water; the creosote bush grows an extensive network of fine roots close to the surface to capture as much water as it can. If there is a ring of creosote plants that are (say) 20 feet in diameter, there's much more opportunity to capture water outside the ring than there is inside the ring – so more new shoots propagate in that direction. As the ring gets bigger and bigger, over thousands and even tens of thousands of years, they tend to leave fairly regularly-spaced individuals in the middle, with the spacing determined by the available rainfall. All of these individual plants are genetic clones, and taken together, there are some colonies that are on the order of 10,000 to 15,000 years old – and over a mile in diameter!

Another interesting fact about the creosote bush is probably mainly driven by how common it is, and how many flowers it has. There are at least 22 species of bees that specialize in feeding from the nectar and pollen of the creosote bush. These bees won't visit the flowers of any other plant. I can't identify any of them, but there's a very good chance that the bee I captured in the photo above is one of those 22 species...