Organ Pipe Cactus National Monument.
At first glance, the monument looks like an exceedingly dry series of plains and valleys crossed and bordered equally dry mountain ranges, the Cipriano Hills and Bates Mountains on the west, the Ajo Mountains on the east, which impings on the western border of the huge Tohno O'Odham Indian Reservation (previously referred to as the Pima Indians), the Puerto Blanco Mountains that cut diagonally across the monument, passing the visitor center.
The flatlands (more or less) that are most significant include the quite large Sonoyta Valley, in which the park visitor center is located, extends northward to make contact with the Ajo Valley. The La Abra Plain lies west of the Puerto Blanco and Sonoyta Mountgains. All of these areas are full of typical and beautiful Sonoran Desert plants and wildlife. Two well-maintained gravel drives allow visitors to become intimately familiar with this singular park. Both drives start at the visitor center. Both are one-way and return drivers back to the center.
The 53-mile Puerto Blanco Drive penetrates the desert country and circles the colorful Puerto Blanco Mountains. The drive passes through mind-boggling variety of sonoran scenery and a highly diversified plant community that includes growths of saguaro, organ pipe, and senita cacti, as well as a welter of woody plants such as the elephant tree (Busera microphylla), and ironwood (Olneya tesota), a member of the legume family. Ironwood is beautiful during the spring when it is covered with lavender flowers.
Careful observation often brings into view specimens of Mormon tea (usually Ephedra trifurcata, but there are others). This plant belongs to an ancient lineage (joint-fir family). We were startled to learn that these spindly-looking plants are actually gymnosperms related to pines. Close inspection of the stems reveals the presence of tiny joints that bear the minute leaves and nearly microscopic cones (male and female, borne on separate plants since the sexes are separate. The "cones" bear bear one to three seeds.
Mormon tea, as indicated above, is a name that may be applied to a variety of other American species, such as E. viridis. Several other common names have been applied to these plants, desert tea, whore's tea, among others.
Ephedra has been used for centuries as medicine for several illnesses, and still is. Chinese species (E. sinica), commonly referred to as Mahuang or Ma Huang, is probably the principal source of the active ingredients ephedrine and pseuephedrine, which are used for nasal decongestants and lung and bronchial constriction, although these same alkaloid drugs are present in American species as well.
A good place to look for Ephedra and other interesting plants along the Puerto Blanco drive (also along the Ajo Mountain Drive) is on the bajadas around the bases of the mountains. Bajadas are produced as the mountains erode and rocks and other debris fall to create the skirt-like slope which retain more water than the mountains themselves. Another name for bajadas is "alluvial fans." But whichever name is applied, the fans provide living space for an amazing diversity of life.
Visitors given to early-morning rising and walking may encounter a large array of birds, reptiles, and interesting mammals that are found on the bajadas during other parts of the day. However, there are two birds that are common at any time of the day, the cactus wren and the phaenopepla (built like a black cardinal).
The Puerto Blanco Drive
Driving the Puerto Blanco Route through the park also discloses many desert washes, usually dry, that support lush growths of trees and cacti, such as ironwood, jojoba, and senita cactus (Cereus schotti), bearing long, black spines. Of course, barrel cactus (Ferocactus wislizeni), organ pipe cactus (Stenocereus thurberi), and the saguaro cactus (Carnegiae gigantea) may be seen throughout the park.
Senita cacus and organ pipe cactus barely get into the United States, which is why this special park was established, i.e, to protect them. It must be pointed out that the Sonora Desert is the only one of the five deserts found in the United States that have these giant columnar cacti growing in it. They are, in fact, the hallmarks of this particular desert. With a casual glance, one might mistake these two cacti for saguaros. However, both the senita and organ pipe cactii do not have a central trunk that gives rise to lateral branches. Instead, both species send shoots up from ground level, none of which are branched.
The distribution of the saguaro cactus extends along the Yaqui River in Sonora, Mexico northward to central Arizona and westward into extreme southeastern California near the Colorado River. This is the largest cactus in the U. S.--we would have said in all of North America but the cardon cactus of Baja California is larger.
The saguaro is a slow grower. A two-year old saguaro is only about a quarter-inch tall, and by 40 years of growth they average only about ten feet in height. The huge specimens that tower fifty feet or more and have several branches (no branches appear on specimens younger than 40 years) are 150 years to more than 200 years of age. The creamy-white, fragrant blossoms occur in circles at the tips of the branches. The flowers are fertilized by various bees, long-tongued bats that lap the nectar, and by the white-winged dove.
The saguaro's two- to three-inch fruits are egg-shaped, and when ripe (July) they are brilliant red and pulpy. The Tohono O'Odham Indians collect them and process them into a thick, sweet syrup, which they ferment into an intoxicating wine. Many of the saguaros bear round holes that lead into gila woodpecker nests, which are often used by elf owls for daylight sleeping. The lining off these nests eventually callous over to a perfect water-proof jug shape that the Indians cut out and use as water containers of canteens.
The saguaro cacti are supported by an internal woody skeleton that consists of twelve or more anastomosing rods that extend the entire length of the trunk. These rods, as well as the soft tissues, are impregnated with silica, giving added strength to the huge plants.
Before we leave the subject of saguaro cacti, we would be remiss if we failed to mention a rare but rather spectacular deformation in this species. The deformation is referred to as a "cristate" or "crested" growth. These weird formations usually grow at the ends of main stems or large side branches. The park service maintains records on the geographic sites of plants bearing these growths, records that are available to visitors. Just ask for information at the visitor center.
What causes these marvelous deformations is unclear. Some botanists believe that they are caused by injuries, but others think they are the result of genetic accidents. Whatever their cause, they are one more reason for visiting the park.
A mixed cactus community
By the time you have negotiated about 12 miles of the Puerto Blanco Drive, it will become apparent that you are in a distinct plant community, one that is referred to as the "Mixed Cactus-Palo Verde Community," although a better name would be "Bajada Community," since these plants are found mainly on the slopes. Actually, these plants, along with creosote bush, comprise more than 50% of the park's flora.
Of course, these are not the only plants that grow in these areas. Mescal (Agave colorata) a beautiful plant that is used in Mexico to ferment an alcoholic beverage of the same name--"mescal," but tequila, none the less. Chain-fruit cholla and other related species are also common on the bajadas.
After curving to the left, visitors are treated to views of the rugged Bates Mountains, foreboding and desert dry, these vastly eroded peaks were built up about 22 to 25 million years ago. This section of the park suffers from very low rainfall and, thus, about 80 percent of the lowlands are covered by a mixture of creosote bush (Larrea tridentata) and triangle-leafed bursage (Ambrosia deltoides).
Regardless of the low plant-species diversity, this community supports a rather large animal fauna, including kangaroo rats, the blacktailed jackrabbit, often seen resting in the shade of shrubs, and many reptiles, including a rather long list of lizards and snakes, including rattlesnakes and several non-poisonous species like the California kingsnake (Lampropeltis getulus californinae). While taking this drive on early mornings, or at twilight, it is not unusual to encounter various mammals, such as wildcats, kangaroo rats, skunks, ringtail cats, and others.
At sign 18 (about 24 miles from the visitor center, a side road (roughly 0.5 mile long) leads to the Quitobaquito Oasis, the only true woodland marshland in Organ Pipe National Monument. Because of the spring-fed water supply, the Indians and wildlife used this oasis. There is even a rare species of pupfish in the springs, and a large number of bird species are normally present.
Finally, the Puerto Blanco Drive passes a side road at mile 33.3 on the left that progresses four miles to the Senita Basin, a pretty valley lying between the Puerto Blanco Mountains and the Sonoyta Mountains. This basin protects what are considered to be some of the best examples of the senita cactus (Lophocereus schotti) in the United States. Several excellent examples of the elephant tree (Bursera microphyllum) are also present. This is one of the few sites where the tree may be found in the U.S. The pink rocks surrounding are 40 to 60-million year old granite.
The Ajo Mountain Drive
Return to the Puerto Blanco Road, turn left onto it, and drive a few miles to contact Arizona State Highway 85, turn left, and follow it back to the visitor center. From there, the Ajo Mountain Drive 21 miles) makes its way through the rugged Ajop Mountains and more of the offerings of the Sonoran desert.
Although shorter than the Puerto Blanco, the Ajo Drive is no less interesting and educational. Much of the higher terrain is rocky and volcanic in origin. In much of the area, a mixed shrub plant community prevails, including species like the foothills palo verde (Cercidium microphjyllum), triangle-leaf bursage, and bush (Encelia farinosa).
There is, of course, a wealth of creosote bush, saguaros, and organ pipe cactus, prickly pears, mesquite, teddy bear cholla (Opuntia bigelovi), so-called because of the dense white spines that cover the body. Because the Ajo Mountains receive considerably more rain than most of the rest of the park, the canyons and valleys support thriving communities of jojoba, agave, rosewood, and juniper trees, especially on rocky terrain.
Visitors will note bird nests in many of the cholla cacti. These nests are principally those of the cactus wren and the curved-bill thrasher. Redtail and Harris hawks build their large, conspicuous nests in the crotches of saguaro cactus branches. But these communities also provide habitats for a variety of other birds, mammals, and reptiles. When the temperatures drop in the evening or in early morning, hiking will usually bring visitors in contact with reptiles such as the desert tortoise (rare and endangered), rattlesnakes, an occasional Gila monster (Heloderma suspectum). Rabbits (desert cottontails, jackrabbits), rodents, javalinas (a heavy-bodied, pig-like animals).
At mid-point on the Ajo Mountain Drive, there is a picnic area that provides tables, grills, and chemical toilets. An interesting 4-mile round-trip trail climbs to Bull Pasture, which is fairly laborious, gaining 800 feet in elevation as it reaches the top. There is no water. Canteens or bottled water are required.
There are many birds in and around the picnic area, including Gambel's quail with their funny little top-knot feathers flitting around, glistening-black phainopeplas, and various handsome sparrows. Rise early, eat breakfast at one of the tables, and sit quietly to draw in animals looking for handouts.
For campers and RVers, there is an inexpensive campground with hookups in nearby Lukeville. The monument also maintains a campground (first come, first served) near the visitor center (fees of $12 collected) with water, restrooms, grills, tables, and a dump station. Fully outfitted camping parks may be found in Ajo thirty miles north of the monument, where there are also plenty of motels.
Problems the park faces
Organ Pipe Cactus National Monument is not without problems. Both sociological and ecological ones have arisen.
The societal problems involve Mexican people who sneak through the the park in order to get into the United States. Most, of course, seek paying jobs. Unfortunately some among those illegally crossing the border do so to bring in illegal drugs.
The illegal crossing is, of course, a dangerous undertaking. It doesn't take long to die of dehydration or of heat prostration in this region. The drug dealers and/or their delivery people all face incarceration or death from shootouts. The park rangers, who constantly attempt to control these undesirable individuals, also face danger. One ranger has already been shot to death.
A major ecological problem emerged via the accidental or purposeful introduction of exotic species from foreign countries. One of the worst problems was the accidental spread into the Sonoran Desert, including Organ Pipe Cactus National Monument, of African bufflegrass, doubtless from Texas where the noxious weed was brought in during 1940 for grazing cattle, goats, and sheep.
The scruffy grass spread vigorously into Sonora, Mexico during the 1960s. This one- to four-foot tall, highly drought-resistant grass was first discovered in Organ Pipe in 1984. It reproduced rapidly and soon began to crowd out native vegetation in the southern part of the park, even threatening to eliminate saguaros in some areas. The grass spread into other parts of the Sonoran Desert through Arizona and into New Mexico. To exacerbate the problem, bufflegrass re-sprouts rapidly following fires, even spreading more rapidly by means of underground runners. This makes the grass an even more daunting enemy of the desert.
Faced with these concerns, the Park Service undertook a major removal in 1998-1999, taking out more than 40 tons of bufflegrass. A year later, it was deduced that mechanical removal was a practical method of controlling the grass, if new seedlings are removed the following growing season.
It is obvious, however, that the control of bufflegrass, and doubtless other dangerous weeds, will require on-going vigilance. But it will be worth the effort. The Park Service estimates that the expense of mechanical control of bufflegrass is less than that required to pick up refuse along the park's roads. To ignore the problem, not to undertake the effort, would put a unique ecosystem in harms way.
Organ Pipe Cactus National Monument is so highly ranked among parks of the world that is has been included as a component of the International Biosphere Reserve. And the sunsets: The sunsets are wonderful. If you spend much time alone in these desert fastnesses, you'll more than likely slip quietly into a solipsistic niche of the universe. We have.
Branley Allan Branson is a professor at the department of Biological Sciences at Eastern Kentucky University. He and his wife Mary Lou have contributed several articles to World & I.
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|Title Annotation:||NATURAL SCIENCE|
|Author:||Branson, Branley Allan|
|Publication:||World and I|
|Date:||Dec 1, 2007|
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