Note: I’m away and offline this week. I’ve set up an auto-post series of this Mexican-Tree-Adventure story in my absence.
One of the biggest differences between the forests of the Western United States, and those of the East is the uniformity of trees. While forests in the East tend to be confusing jumbles of a dozen or more different types of tree, forests in the West generally consist of only a few trees in a given area, and in many locations, just one. This in turn makes it easier to recognize a given species of tree. For example, if you live in Denver long enough, and routinely hike, or bike, or just drive through the foothills West of the city, no matter how disinterested you are, you’ll eventually learn to recognize a Ponderosa Pine.
The type of predominant tree or trees in Western forests almost always depends on elevation of the forest in question. Lower areas in the Intermountain West generally have no trees, while mountains and high plateaus have lots of tall trees. In between there’s usually a sort of transition zone, where stubby “sort-of” trees form open “woodlands”. The most common type of woodland in the West is “piñon-juniper” woodland, named for the two types of “trees” that comprise it. Juniper is usually the more shrub-like of the two, while piñon looks more like the first real “tree” as one climbs out of the desert, or the last as one descends into it.
During my first years in the West, piñons were always something to be passed by on the way to mountain or desert hiking or camping destinations. But several years ago, some friends and I began regularly visiting a network of mountain bike trails in extreme Southwestern Utah (examples here and here.) The trails lie atop two adjacent flat-topped mesas at roughly 5,500 feet, and the tops are covered in piñons. Over a few years, visiting these mesas three or four times a year, I came to enjoy the smell, the wide-open spacing, and eventually the distinctive silhouette of piñons, and on a whim one year I bought a book about them: The Piñon Pine, by Ronald Lanner. (I’ve mentioned Ron previously, in this post.) I browsed the book couple of times, then left it in the seat-pocket of my truck, along with the Utah topographical atlas and the Audubon Guide to the Night Sky. There it rested, always on-hand, but half-forgotten, for a couple of years.
On October 2005, Arizona Steve and I were hiking Notch Peak in Utah’s West Desert. In the afternoon, returning to the truck, we followed a shallow canyon lined with piñons. We noticed a few nuts on the ground, looked about, and saw that virtually every piñon in sight was full of open cones, each laden with nuts. We spent the next hour collecting, returning to the truck with a zip-lock baggie full of nuts.
Our camp dinner that evening was spaghetti and pesto, and roasted pine nuts sounded like a welcome addition, but neither of us had much of an idea how pine nuts are actually roasted. Remembering Lanner’s book in the seat pocket, we followed his instructions, crafting a cooking sheet of sorts out of aluminum foil and roasted the lot over an open fire. They turned out delicious, and we spent the rest of the trip snacking on pine nuts and congratulating ourselves on our Euell Gibbons-like prowess at finding and preparing foods in the wild.
When I returned home, I was curious enough to finally read Lanner’s book cover to cover, and found it fascinating. Early on in the book, there’s a chapter in which Lanner briefly describes the various species of piñon that occur in the U.S and Mexico, before focusing for the remainder of the book on the two most common types of piñon in the U.S.: Singleleaf and Colorado piñon. One of these caught my eye:
Martinez piñon (Pinus maximartiezii Rzedowski) is one of the newest of the piñon pines to science. This species, with long needles and inch-long nuts, grows in a remote canyon in Mexico’s state of Zacatecas… the incredible cone- up to ten inches long and four pounds in weight when green- is one of the most bizarre products of any pine anywhere.
Ten inch cones? Inch-long pine nuts? It sounded remarkable. I was curious enough to spend an hour googling the Martinez piñon, and that hour lead to several more hours and eventually to my search for the Blue Piñon, and a crash course in pine botany.
Most people, when they think about pines at all, assume that any tree with needles is a “pine tree”, which is not the case. Pines are evergreen trees that bear cones, and whose needles are clustered together in little bundles called fascicles, which connect the needles to the branch. Spruces, firs, Douglas firs, hemlocks and most everything on a Christmas tree lot are not pines. If you live in the Northeastern U.S., the most common pine you’re likely to see is Eastern White Pine. If you live in Denver, it’s Ponderosa Pine. If you live in Michigan, Jack Pine is a true pine. In Oregon, you’re likely to see Lodgepole or Jeffrey Pine.
Pines have been around for a couple of hundred million years, and for at least the last 135 million, they’ve been divided into two distinct sub-genera: Haploxylon, or “soft” pines and Diploxylon, or “hard” pines. The “soft” and “hard” originally referred to the qualities of the wood, but the reference has lost its meaning over time as more and more species have become known to botanists; there are some “soft” pines with harder, less workable wood than some “hard” pines. The real difference between soft and hard pines is in the anatomy of the needles and wood. In the center of every pine needle is a fibrovascular bundle which carries essential nutrients along the length of the needle. In soft pines, each needle has a single microvascular bundle at its center. In hard pines, each needle bears two such bundles. About a third of all pines are soft pines.
Soft pines, in turn, are divided into two sections: Cembra and Paracembra. Cembra are those soft pines in which the umbro, or tip of each scale of the cone, points downward, as they do on the cones of Sugar Pine and Limber Pine. Paracembra are those soft pines in which the umbro is thick, reflexed outward, and sometimes thorned. All piñons and nut pines are Paracembra.
Depending on who’s counting, there are between eleven and fifteen distinct species of piñon, ranging from Central Mexico to Southern Idaho. The reason for the variable number of species is that botanists have and continue to disagree on whether some particular types of piñon are in fact species, varieties, or hybrids.
In the US, piñons generally grow in “woodlands”, most commonly occurring with one of two species of juniper. Rising out of the desert, scattered junipers are generally the first plant that could conceivably be called a “tree”. As the altitude starts to increase, piñons start to appear, become more common, and eventually predominate until the piñon -juniper woodland becomes a piñon woodland. Atop flat-topped mesas at the right altitude and latitude, piñons can form pure, vast, open yet unbroken woodlands.
All piñons have wingless seeds, or nuts, which means that piñons require a dispersal agent to reproduce and expand their range. In the Western U.S., the most effective dispersal agents are corvids, a group of birds that include piñon jays and scrub jays. Corvids harvest piñon seeds, transport them some distance, and then bury them in underground caches. Because they cache more than they actually eat, some number of these buried seeds eventually germinate and grow into new piñons. After about 25 years, these new piñons develop nut-bearing cones, and the cycle is repeated.
Here in the U.S., the vast majority of piñons are of two species: Colorado Piñon, Pinus edulis, and Singleleaf Piñon, Pinus monophyla. The two are easy to tell apart. Colorado piñons have two needles per fascicle, while Singleleaf Piñons are the only pine to bear one needle per fascicle. There are other differences: Singleleaf nuts are a bit longer, have thinner shells, and are- in my opinion- a bit tastier. Singleleaf Piñon dominates throughout Nevada, Western Utah, California and Arizona. Colorado Piñon dominates in Colorado, New Mexico and Eastern Utah. In several areas in Utah and Arizona the two types grow together and often hybridize.
Paleobotanists believe that Singleleaf Piñon arose some 20 million years ago as a mutant offshoot of Colorado Piñon. The mutant population was somehow separated and thrived. Over millions of years the ranges of these two species ebbed and flowed across Northern Mexico and the Western U.S countless times, driven by changes in climate and topography, until reaching their present ranges within the last 5,000 years.
All fifteen or so different species of piñon occur in Mexico. And Mexico doesn’t just have a lot of different types of piñon; it has a lot of different types of pine in general. Of the one hundred some-odd species of pine in the world, more than fifty occur in Mexico, and many of those occur nowhere else.
Botanists regard Mexico as a “secondary center of pine evolution.” Secondary, because it’s thought that pines originated in Asia, but once they made it over and down to Mexico, they speciated rapidly. Mexican geography is a jumble of mountains- some ranging up to 4,000 meters- and valleys sandwiched between two oceans. As climate and precipitation have varied through the millennia, Mexico has supported a myriad of ever-changing microclimates, leading to repeated incidences of speciation, reunion, hybridization and extinction. One of the challenges of rare Mexican pines is determining whether they represent a new species, a hybridization event, or the last stand of rapidly disappearing relict species. This diversity lead to the discovery of new species well into the second half of the twentieth century, and Mexico remains a Mecca of sorts for pine botanists.
All About Jerzy Rzedowski
In 1946, two Polish Jewish concentration camp survivors, Arnold Rzedowski and his 20 year-old son Jerzy, emigrated to Mexico. Arnold remained only a few years before continuing on to Israel, but Jerzy, who had found that he liked the land and the culture, decided to remain. He found work as a translator at the Polish embassy, where he worked for a few years while mastering Spanish. In 1950, he resumed his studies which had been interrupted by the war. Although lacking documentation of his prior academic accomplishments, he passed the rigorous entrance examination of the Instituto Politécnico Nacional and began his studies in biology, later concentrating in botany.
Following his dissertation in 1954 on the vegetation of Pedregal de San Angel, Rzedowski worked first for Instituto Nacional de Investigaciones Forestales and then as a botanical explorer for Syntex Laboratories, followed by a period of work and further study in Europe, before earning his doctorate in 1961 from the Universidad Nacional Autónoma de México. Later that year, Dr. Rzedowski accepted a position as professor and investigator at the Escuela Nacional de Ciencias Biológicas, in which he spent the next two decades.
In 1963, Rzedowski found some unusual pine nuts for sale in the market of Juchipila, a moderate-sized town in extreme southern Zacatecas state. The nuts were an inch long, with shells a millimeter thick. Conversations with local inhabitants led him to Cerro Piñones, an 8,000 foot mesa some twelve kilometers southwest of town, and it was there that he discovered the Blue Piñon. Rzedowksi named it Pinus maximartinezii, for his mentor and good friend, Maximo Martinez (1888 – 1964), the father of modern Mexican botany. (Several years later, Rzedowski had a pine named for himself- Pinus Rzedowski- probably Mexico’s second rarest pine.)
Pinus maximartinezii today is known by several names. Botanists, when not referring to it by its scientific name, generally refer to it as Maxipiñon or Martinez Piñon. Locals, who of course knew of the tree long before Rzedowski, commonly refer to it as Piñon Azul (Blue Piñon) or Piñon Grande (Big Piñon). The “blue” refers to the color of the needles, which bear a light blue tint at times, especially after rains.
The trees cones are by far the biggest of any piñon, and one of the biggest of any pine. Growing as big as pineapples, cones develop for 2 years before drying out and opening, typically bearing forty to fifty seeds each.
In 1985, a team of Mexican researchers mapped the entire range of the Blue Piñon. Its range is limited to 10 square kilometers, all of which are private land, spread around the high flanks of Cerro Piñones, above the village of Pueblo Viejo, at the very southern end of the Sierra Modrones mountain range. They estimated the total number of trees at between 2,000 and 2,500. Several sources I located noted the poor reproduction of the species, attributed to overgrazing, brush fires, and seed collection by locals.