Oaxaca Journal (7 page)

Clouds on the mountaintops—fabulous vista! As we climb a little higher, Boone points out a magnificent
Douglas fir on a precipitous outcropping to our left. This stand of Douglas firs was discovered, he adds, in 1994, by a botanist from the Hungarian Museum of Natural History. It is the southernmost population of Douglas firs in the world. Boone goes on to speak of Oaxaca as a uniquely rich botanical borderland where plants of northern origin, like these pines, mingle with South American plants that have migrated north.

Other plants:
Abies oaxacana
. Madrones—
Arbutus
, with red wood and peeling bark. Indian paintbrush, orange, along the road, admixed with blue lupins and a purple lobelia. Small yellow flowers—marigolds. Other yellow flowers are dismissed as DYCs—damned yellow composites. The plants of the Compositae family include dandelions, asters, thistles, and others, where the flower head is composed of florets radiating out from a central disc. They are among the most common of all wildflowers and often difficult to identify. Bird-watchers use similar phrases: There are fine, interesting birds, and then there are the LGBs—little gray birds—flitting everywhere, distracting the attention.

The bus climbs higher and higher, and now we get to the top of the ridge, 8,400 feet above sea level. A lumber road goes off to the left, up to the top of Cerro San Felipe. It is colder here, wetter, and more moss is to be seen. As we start our descent, we drive just a mile or two, and stop at a small gully called Río Frío. John Mickel immediately identifies a new fern, a spleenwort,
Asplenium hallbergii
. I ask, in an idiotic way, “Who was Hallberg?” John looks at me strangely, and says “Ask Boone!”

Then he swoops off to another fern,
Anogramma leptophylla
. “This is one of the great ferns of the world! It’s full size, only an inch or two high. It’s a cutie, only occurs at high elevations.” He moves quickly to another fern,
Adiantum
, a maidenhair, and another, an
Asplenium
.

John becomes tremendously enthusiastic over almost every fern we see, and when he was asked which was his favorite, he had difficulty giving an answer. “When speaking on fern cultivation,” he said, “I find myself citing the ostrich fern as my favorite, and a minute later the autumn fern is my favorite. In fact, I have three hundred favorite ferns. I love the ostrich fern for its great shuttlecock form and its wide-creeping runners, and the autumn fern for its red sori and dark lustrous fronds that remain standing upright and green all through the winter. I like the Himalayan maidenhair for its delicate beauty. Some of my favorites have special memories—I found the Mexican woodfern on top of Cerro San Felipe, here in Oaxaca, after its not having been collected anywhere for over a hundred years. For scientific study,
Anemia
and
Elaphoglossum
claim my vote, though
Cheilanthes
and
Selaginella
are close behind. How do you choose among your children? They are all wonderful, and the more you know them personally, the more you love them.”

My attention wanders a bit—I see we are surrounded by sweet-smelling salvia, sage. And beautiful calla lilies in a field, in which there is a notice in Spanish which I puzzle out slowly: Anyone Who Does Not Respect This Property Will Be Jailed. Or shot, or beheaded, or castrated.

“Here’s
Pleopeltis interjecta
,” John continues, “Big round sori with yellow spores,” he says, looking at the clustered sporangia,
“a splendid specimen! Another
Mildella
, with smooth margins,
M. intramarginalis
. If it’s serrate, it’s
serratifolia
.” My head is spinning with all the different ferns and their names, and I move away and wander a bit by myself, homing in on a wonderful tree full of mosses and lichens. When ferns get too much for me, I need to go lower, to the simpler, less demanding forms. To appreciate this microworld one needs a powerful
hand lens—we all carry these—or even (as Dick has) a pocket microscope, to see the tiny stars of mosses, the fairy cups of lichens.

I join Robbin, who is standing by a stream. He points out liverworts, and a hornwort,
Anthoceros
, in which one can see a blue-green, nitrogen-fixing bacterium,
Nostoc
. Animals, higher plants, even hornworts, he says, may think themselves superior, but ultimately we are all dependent on about a hundred species of bacteria, for only they know the secret of fixing the air’s nitrogen so that we can build our proteins.

“Here’s an
Elaphoglossum
, at last!” says John Mickel, climbing a crag. “There are six hundred species. They all look alike. This is …” He hems and haws, turning it this way and that under his lens. “This is
E. pringlei
, I guess.”

Most ferns are fairly easy to distinguish and identify, by the size and form and color of their fronds, the way they are divided, their veins, the character and location of their sori, their general habitus. But
Elaphoglossum
is tricky in this regard. In his swift, minute, and almost intuitive examination, John must have looked at some very subtle differences, such as the form and distribution of the blade scales, characteristics visible only with a hand lens.

When I ask Boone about
Asplenium hallbergii
he is tactful enough to overlook my blunder, my failure to understand that
he
is Hallberg, that this is a species named in honor of him: Boone Hallberg. (I had failed to realize this, or forgotten it, because to everyone here, he is just “Boone.”) I am intrigued by the mysterious Boone. I pick up fragments: He is not just a systematic botanist, Scott says. His interest has always been more
in agriculture and ecology. He came to Mexico as a young man, drawn by the special needs of Oaxaca. He was especially concerned with deforestation, and tried hard to get people in different villages interested in the replanting of trees. He seemed to have a special gift for communicating with the local people directly and easily, getting things started from a grassroots level. He had been interested, too, in agricultural problems and possibilities, and especially the potentials of new sorts of corn.

Boone’s Spanish seems as fluent and idiomatic as that of the local Oaxacans—he is earnestly conversing now with Fernando, the driver’s son. Fernando is perhaps sixty years Boone’s junior, but they are completely at ease with one another, the old man and the boy. Indeed, I get the sense that he is seen as something of a father figure by the local people.

I remember now—I failed to make the connection earlier—that Mickel and Beitel’s book, the fern bible, is dedicated to Boone, for it was Boone who originally suggested to John that he catalog the ferns of Oaxaca. Oaxaca, he said, was probably richer in ferns than any other state in Mexico, and also among the least studied. Incited by Boone’s suggestion, John had made a series of trips during the sixties and seventies, collecting nearly five thousand specimens from all over the state. Boone himself contributed another five hundred in the early seventies, many of them rarities. By 1988, when the
Flora
was published, John and his colleagues had discovered no fewer than sixty-five new species of fern, and catalogued a grand total of 690 species, in Oaxaca alone. Boone had been behind all this, providing room and board, guide service, logistical support and transportation.

Here in Mexico, Boone is saying, you have to use your brains to know what’s going on. In the States everything is published, organized, known. Here it is under the surface, the mind is challenged all the while.

The richness of Oaxaca’s ferns seems miraculous, for there are no more than a hundred or so in New England, perhaps four hundred species in the whole of North America. There are ferns in all latitudes—a brave thirty species in Greenland, for example—but far more as one goes toward the Equator. There are nearly 1,200 in Costa Rica, where Robbin teaches a course every year. And there is an incredible variety of shapes, sizes, formats, whole families of ferns with no exemplars in the temperate zones. In Oaxaca, too, there is every sort of habitat, from the arid central valley (itself a 5,000-foot-high plateau) to rain forest and cloud forest, to mountainsides. Tree ferns, climbing ferns, filmy ferns, shoestring ferns, they are all here, in unparalleled diversity.

Robbin’s mind and mine, we discover, have both been going back to the little hornwort we had seen near the stream, with its precious, symbiotic freight of nitrogen-fixing bacteria. We are bathed in nitrogen, the atmosphere is four-fifths nitrogen. All of us, animals and plants and fungi alike, need it to manufacture nucleic and amino acids and peptides and proteins. But no organism other than bacteria can make use of it directly, so we are all dependent on these nitrogen-fixing bacteria to convert
atmospheric nitrogen into forms of nitrogen the rest of us can use. Without this, life on Earth would not have got very far.

Intensive cultivation of a single crop tends to deplete the nitrogen in the soil quickly, but the Mesoamericans discovered early on, as other agricultural people did, by trial and error and experimentation, that beans or peas grown along with the corn could help replenish the soil more rapidly. (It was also discovered that alder trees, though not legumes, could similarly fertilize and enrich the soil, making possible a more intensive cultivation of other crops. The planting of alders had become an integral part of Mexican agriculture by 300
B.C.
) In Europe, Robbin points out, many other legumes such as clover and alfalfa and lupin were grown as animal forage, and these were even more effective in restoring nitrogen to the soil than peas or beans. In China and Vietnam, he continues, warming to his theme, the great restorer is not a legume, not a flowering plant at all, but a tiny water fern,
Azolla
, which engulfs and lives with a nitrogen-fixing cyanobacterium,
Anabaena azollae
. Rice, half-submerged in rice paddies, grows much more vigorously if
Azolla
is ground into the mud—in Vietnam, they call this green manure.

Even though this practical knowledge had been around since the Stone Age, no one really knew why it worked, just that it did. Only in the nineteenth century was it realized that the strange nodules often present on the roots of legumes were full of bacteria, and that these, with their special enzymes, could fix atmospheric nitrogen and make it available to the plant (similarly with the nodules on alders, and the
Anabaena
in
Azolla
). With the eventual decomposition of such plants, the
now-assimilable nitrogen compounds would be released into the soil.
^*

It was also realized around this time that however carefully one fertilized the soil with compost or with animal waste, however much one grew beans and vetches and clover and lupin, one could not feed an exploding human population without additional, inorganic fertilizers which were extremely nitrogen-rich. By the end of the nineteenth century, it was becoming clear that a nitrogen crisis was pending, that one had to have more ammonia or nitrates available if an exponentially expanding human population was not to starve—the catastrophe Malthus had dreamt of a century earlier. There was a rush on the South American beds of nitrates and guano (the Peruvians had long used these to guarantee a fertile soil), but these were exhausted in a few decades. Thus the supreme challenge, by the beginning of the twentieth century, was to make synthetic ammonia, for there was no longer enough natural fertilizer on the planet.