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It's the signature plant of the Mohave Desert...and Angela O'Callaghan is always happy to see creosote bushes.

While I was driving past some of the thousands of construction sites around our valley, I couldn't help but notice a preponderance of two plants. One was Russian thistle, alias tumbleweed, and the other was creosote bush. Well, I'd be perfectly happy not to see tumbleweed ever again, miserable thing that it is, but I'm always relieved to see the creosote.

Now just in case you're not sure what I'm talking about, the tumbleweed is more likely to be closer to the road, because it grows best in disturbed soils. If you touch this character, you'll be afflicted with multiple, small but painful, thorns, prickles and spines.

Creosote bush, on the other hand, is the signature plant of the Mojave. Certainly there are others, but creosote is the big one. It's evergreen, and the branches may be quite spread out. The leaves are very small, thick, and shiny from the wax that helps them hold onto water. Some people call it 'chaparral', but apparently there are other plants with that name. Because it has that very airy kind of profile, some people don't like it, and it generally gets destroyed by construction equipment. But if we can get away from the idea that a shrub has to have that dense, compact habit, then creosote might be the plant whose time has come.

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Creosote flowers From about mid-winter through spring, it's covered with pretty little yellow flowers, but year-round it's an interesting shrub that I think we should be using more in desert landscaping. For one thing, it's possibly the most drought tolerant plant in the Mojave. Out in the wild, it survives on very little water. My colleague ML Robinson was telling me about a yard in the Northeastern part of town where a seven-foot creosote bush, actually a small tree, is a center of attention in the landscape. Since it gets whatever water it needs from the rest of the plantings, the homeowner just has to prune it occasionally. Even in the wild it can reach a height of ten feet.

And it has a unique scent - somebody described it as the smell of rain.

If you can see one of these plants from the road is an old plant. I read in the National Park Service website that a one foot tall creosote bush may be ten years old. Like so many survivors in the Mojave environment, it grows mighty slowly. That only makes sense. After all, when there's so little in the line of resources - like fertility and water - it's in the plant's best interest to use those resources frugally. By the way, there are creosotes in the Mojave, as well as in the Sonora and in the Chihuahua, and they all seem to have significant adaptations to help them survive their environments. Not that we'd see the differences with a naked eye, of course.

Although creosotes produce a hefty number of seeds each year, very few of them germinate. In the wild, when you see a clump of creosotes, what you're looking at is actually one plant that originated from a central crown. The central crown ultimately dies, and the remaining ring of plants looks like a set of independent shrubs. But they're not, in fact, they're more akin to the cuttings that we take of houseplants. Because of this, it's not something that is likely to become a weed.

There's a myth that creosotes prevent other plants from growing around or underneath them. That turns out not to be exactly true. They mostly prevent their own seeds from becoming new plants! When you think about it, doesn't this make sense. After all, here's a plant that survives in an extremely harsh environment - as I said before, limited water and fertility. Now, creosote seedlings would be likely to use up the exact same resources that the parent plant needs. Nobody benefits from a situation like that.

And the seeds are fussy little creatures anyway. According to the book 'Seed Propagation of Native California Plants' they need to be soaked overnight in water, and then planted in warm soil. Oddly enough, seedlings can't deal with water stress. So, there's usually a low germination percentage.

Even so, when you consider that these rings of plants are basically single plants, they may be as much as 10,000 years old - some of the oldest life on earth. Another reason why it's not necessary for it to have a lot of seedlings around.

Some nurseries are now carrying this plant, which means you don't have to worry about the seed germination problem. So, when you're thinking about something different for your low-water-use landscape, why not think creosote?

For KNPR's Desert Bloom, this is Dr. Angela O'Callaghan of the University of Nevada Cooperative Extension.

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Tuesday, November 15, 2005
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