_by_ Ross Calvin
The problem of discussing plant life becomes complicated, for some of
those arriving in New Mexico may be compound microscope botanists, some
collectors, others pathologists, still others geneticists. Some will be
chemists or mathematicians, some others untrained in the ways of growing
things and mainly interested in seeing while they tour. But one thing is
fairly certain—most visitors will come from a distance, so it may be
useful to invite them to observe what they can readily see on the way
hither, which will be a relatively painless method of amassing some
information.
Yet the method of arrival itself suggests choices, options, and
exercises in probability. Do visitors come in covered wagons, or in jet
planes; by bus, car, train, or some other way? The most convenient way,
doubtless, is by plane traveling six hundred miles an hour at a height
of some thirty thousand feet; but the most rewarding way is by saddle or
on foot as the early collectors came.
Since one cannot know his own country well if he knows no other, a
visitor from the east arriving at an altitude of five miles will
probably be more conscious than others of drastic changes in the
landscape when he first looks down on New Mexico. Instead of the
universal green of the east, he will note the earth as an unaccustomed
tawny, reddish brown expanse, and this will be its common color through
most months of the year. He will note the absence of rivers, but the
presence of mountains which generally ring the horizon. He will wonder,
after traversing the border counties at the western edge of the Great
Plains, at the infrequency of plowlands, and will promptly conclude that
New Mexico is one vast, bare desert—an impression that will be corrected
rapidly when he visits the dark National Forests where the slim, crowded
spruces and firs tower skyward.
The visitor from El Paso, as the Chihuahua desert (the name is fairly
deserved) slides backward underneath him, will be amazed at the
serpentine stripe of vivid verdure below, all completely leveled, and
all marked off by geometrical lines and tightly bordered by pale hills
where the vegetation is reduced to tiny dots not tall enough to cast a
shadow. Still proceeding north, he will presently be above a ninety-mile
stretch where the vegetation is so skimpy and the river so closely boxed
in by desolate hills that Spanish explorers bestowed on it the sinister
name _Jornada del Muerto_—Dead Man’s Journey, which is self-explanatory.
But on the other hand, a visitor descending into New Mexico from the
northland in wintertime above this same Rio Grande will traverse a
featureless jumble of peaks on which the black coniferous forest no
longer shows as black at all but, snow-encased, gleams as white as the
naked snowfields themselves. And he will find incredible the immense
range of climate spanned in a flight only an hour long.
The jet traveler approaching from the west beholds the greatest, most
spectacular panorama of all, the true wasteland of the desert, with vast
blocks uplifted from out of earth’s crust, plateaus dissected by giant
empty canyons whose walls are seared to utter nudity by ages of the most
intense sunshine on our continent. Here the architecture of nature is
all designed on a gigantic scale, and the climate exhibits influences of
a mighty ocean, of towering mountain chains, and the range of wandering
planetary winds which created the desert. From the altitude of a
cruising jet, the distances, the speed, the color, and the light are
indescribably exhilarating.
Since the traveler arriving from any direction can see for
identification only a few species, it will suffice to point out only two
of the harbingers of eastern New Mexico, both of which are dominant on
that area of the Great Plains: the blue grama grass, which in fall and
winter bears the graceful sickle-shaped head, and the small _Yucca
glauca_ which cannot be mistaken for anything else.
Along the northern line, the visitor should look for the somber, almost
black, forest of spruce and fir with its white patches of aspen on the
10,000-foot slopes. Descending farther southward, even a casual observer
will note that these species give way first to the yellow pines, then to
the junipers (“cedars”) and dwarf pines or piñons. The visitor arriving
from the south will find most conspicuous of all the olive-green
creosote bush in its summer-winter foliage, next, the omnipresent
mesquite (_Prosopis_), then the various _Opuntia_ cacti (chollas and
prickly pears), and the yuccas.
As he comes in from Arizona, the splendid saguaros will beckon him
toward the gateway of New Mexico, but they will nowhere enter it
themselves. The vase-shaped body of the ocotillo consisting of
unbranching, ten-foot wands should be recognized at a glance, as
likewise should the various yuccas and agaves. And in early springtime,
a low tree with a rounded mass of golden bloom will joyously proclaim
its identity as a paloverde.
The desert plants thus enumerated can be recognized along various
stretches of U.S. 66 as one holds his speed at a conservative ninety or,
even better, at a conservative sixty.
The amateur scientist will need to do some homework before he learns
much systematic botany or plant physiology. It takes considerable study
to comprehend the slow, age-long process which has resulted in the
evolution of all this grotesque vegetation: the interaction of extreme
aridity, high temperature, low humidity, high evaporation, infrequent
precipitation, the hostility of numerous chemical solutions, and the
natural rapacity of the animal population. Each plant must have an
adaptation of its own, from the tiny winter annual, which must race
through its course from a tender rosette to ripened seed before the
searing sunshine arrives, on up through the series to the stoic saguaro,
which seems able to scorn nature’s enmity.
A final warning to the air traveler. He should be sure before deplaning
that he has observed a _bajada_. It is a must. Bajada is one name,
outwash slope is another, alluvial fan is still another. The stewardess
should inquire of each student, and if his answer is “no,” she should
reply, “Then you’ve just flunked the course.” A bajada is the most
characteristic single feature of all in the sloping, stony topography of
the desert—and remember that the surface of the desert is regularly
sloping and stony. The Spanish word itself means only a down slope, but
it has come to have a semitechnical sense—a fan-shaped apron of rocky
debris at the foot of a mountain where it has settled out of the summer
torrents and there keeps accumulating in successive floods. As the mass
builds up, the bigger fragments drop out closest to the parent crag,
then the small ones, finally the coarse gravel, and lowest of all on the
slope the fine sand. Thus the fragments are graduated in size, in
distance traveled, and in the nature of soil resulting. As the fan
increases in size and laps up higher and higher on the mountain’s flank,
the geologists often describe the result by saying that the mountain “is
burying itself under its own debris.” From the air, the lines of
drainage will be seen to have assumed the form of a tree with its trunk
downward, its branches high in air. But the most interesting aspect of a
bajada is the nice proportion which nature works out between the plant
species and their location on the curve.