Another clueless, airhead model

Monday, September 28, 2009

Ay Chihuahua!

Didn’t botanize too far south, maybe 40 miles. As far as Sevietta National Wildlife Refuge. The Chihuahua Desert is the largest of the North American Deserts (Chihuahua, Great Basin, Sonoran and Mojave). I was at the northern extreme. Creosote shrub was still present but not in abundance like the southern range. Link to this to feed your head:

Botdar was on auto-pilot and set to maximum. When I felt the tug to pull off of I-25 I knew I would encounter species I hadn’t seen in the last month. And there it was – bush penstemon (Penstemon ambiguus). A common desert plant but not easy to see because it was going dormant yet had a few flowers left. Like all desert flora it has evolved to offset the summer heat and dessicating winds. Leaves are small and linear but this is not true for all species. Some plants have a large leaf surface area but if you look close, e.g. at a globe mallow you’ll notice tiny white bumps covering the entire surface. These are “Trichomes”; hair-like structures that reflect solar rays therefore reduceing the amount of surface evaporation. Trichomes may also deter grazing.

Bush penstemon also has a very large and deep tap root. Snake Broomweed has a resinous coating on the leaves. Halophytes (salt tolerant) exude salts away from their cells and many are succulents. The large leaves of stink gourd are hairy and angular which prevent the sun’s rays from striking directly. Trees like the Rio Grande Cottonwood had deep roots and leaves that loosely “flutter” to avoid direct sunlight. The mighty process of evolution is apparent everywhere. The classics of all time are the cacti with their modified leaves as spines and photosynthesizing through their pads (stems). In the cool of the night they take in CO2 but with no sunlight to kick in photosynthesis to make sugars they have to process the CO2 temporarily into Malic Acid. Come daylight the sunlight breaks the acid down into CO2 and from there sugars (carbohydrates) can be made to power cell metabolism. Some guys a lot smarter than me figured this out and received a Nobel Peace Prize for their efforts.

For a few hours I roamed the desert region of Silvietta NWR unencumbered. I was hoping to come across a rattlesnake but the only reptile was a lizard. One jackrabbit. Most animals retire when the sun is peaking; preferring to forage or hunt at night when it’s cooler. I toyed with the idea of a night hike but the logistics weren’t there.

Five more days in New Mexico. Soon I’ll return to sad, depressing Angleton, TX.

No comments: