Jun 25, 2006

But Its a Dry Heat

Some of the vegetation in front of Casa Sneed. People living in Arizona often dismiss the summer heat by saying, "but it is a dry heat." Well, so's an oven, but I'm not sticking my head in one! (Thank you, thank you very much. I'll be appearing here all week folks.) Many people think all deserts look like a scene from Lawrence of Arabia. Sand dunes with an occasional oasis. It isn't so. The Sneed family lives slightly north of the Mexico border, in the high Sonoran Desert. This particular desert is the hottest of the American deserts and covers the very southeast potion of California, southern Arizona and part of the Mexican state of Sonora. It is not all sand and cactus, but it is hot, hot, hot. It has periods of regular precipitation, late summer and winter, so it has a diverse array of vegetation, the most famous of which is the Saguaro cactus. We also have a variety of trees and shrubs that have adapted to this harsh environment. This mature mesquite tree is in front of my neighbor's house. It was a 15 gallon plant 11 years ago, its crown is now over 20 feet tall. You can see it is well adapted to the desert. One adaptation is these tiny leaves that help to minimize transpiration (loss of water). The mesquite has very deep roots to search for water. The tap root of a mesquite is often thicker than its trunk. This has caused many ranchers in the west to declare the mesquite a weed, because it crowds out grassland. They have tried in vain to eradicate it. Given mequite trees or cows, I vote for the trees. This mesquite grove, called a bosque, has flourished in a retention basin. It was two or three trees a decade ago. Now many more "volunteers" have emerged. This is a Mexican Bird of Paradise, a very popular drought-resistant plant used in landscaping. This one is in a neighbor's yard. In the background you can see the same bipinnated, two parallel rows of tiny leaves per stem, that is shown in the mesquite photo above. You can see why this tree is called Palo Verde, literally "Green Stick", in Spanish. It has green bark to aid in photosynthesis because it has needles, like a pine tree, rather than leaves. This prevents transpiration. The Sonoran desert is a remarkable place. You should see it sometime. Tag:

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