The Magazine of the Arnold Arboretum - VOLUME 78 NUMBER 3
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The Magazine of the Arnold Arboretum VOLUME 78 • NUMBER 3
The Magazine of the Arnold Arboretum
V O L U M E 7 8 • N UM B E R 3 • 2 0 2 1 CONTENTS
Arnoldia (ISSN 0004–2633; USPS 866–100) 2 Building a Comprehensive Plant Collection
is published quarterly by the Arnold Arboretum Jeffrey D. Carstens
of Harvard University. Periodicals postage paid
at Boston, Massachusetts. 5 A Conservation SOS: Polygonum hickmanii
Holly Forbes
Annual subscriptions are $20.00 domestic or
$25.00 international, payable in U.S. dollars. 7 An Unusual Autumn at the Dana Greenhouses
Subscribe and purchase back issues online at Tiffany Enzenbacher
https://arboretum.harvard.edu/arnoldia/ or send
orders, remittances, change-of-address notices, 10 A Brief History of Juglandaceae
and all other subscription-related communica- Jonas Frei
tions to Circulation Manager, Arnoldia, Arnold
Arboretum, 125 Arborway, Boston, MA 02130-
18 Discovering the Majestic Mai Hing Sam of Laos
3500. Telephone 617.524.1718; fax 617.524.1418; Gretchen C. Coffman
e-mail arnoldia@arnarb.harvard.edu 28 Backyard Climate Solutions
Arnold Arboretum members receive a subscrip- Edward K. Faison
tion to Arnoldia as a membership benefit. To
become a member or receive more information,
38 A New Look at Boston Common Trees
please call Wendy Krauss at 617.384.5766 or Kelsey Allen and W. Wyatt Oswald
email wendy_krauss@harvard.edu 42 Case of the Anthropocene
Postmaster: Send address changes to Jonathan Damery
Arnoldia Circulation Manager 44 Planting Edo: Pinus thunbergii
The Arnold Arboretum Rachel Saunders
125 Arborway
Boston, MA 02130–3500 Front and back cover: Jonas Frei’s collection of walnut
family fruits includes a disc-shaped wheel wingnut (Cyc-
Jonathan Damery, Editor
locarya paliurus, back cover) among other more familiar-
David Hakas, Editorial Intern
Andy Winther, Designer looking species. Photo by Jonas Frei.
Inside front cover: Glyptostrobus pensilis is the only living
Editorial Committee member of a genus that was once widespread throughout
Anthony S. Aiello the Northern Hemisphere. The illustration shows a Glypto-
Peter Del Tredici strobus fossil collected near Reading, England. From Gard-
Michael S. Dosmann ner, J. S. 1886. British Eocene Flora (vol. 2, part 3). London:
William (Ned) Friedman Palaeontographical Society. Biodiversity Heritage Library.
Jon Hetman
Julie Moir Messervy Inside back cover: The precision of Itoˉ Jakuchuˉ’s observa-
Jonathan Shaw tions is evident in Old Pine, an ink painting in which he
fluidly captures the essence of a Japanese black pine (Pinus
thunbergii). Painting: Harvard Art Museums, promised gift
Copyright © 2021. The President and
Fellows of Harvard College of Robert S. and Betsy G. Feinberg, © photography: John
Tsantes and Neil Greentree © Robert Feinberg (TL42147.7).
Photograph of Japanese black pine (11371*M) at Arnold
Arboretum by Jonathan Damery.
Publication note: Volume 78 will comprise six issues
published on the current quarterly schedule. Volume 79
will begin with the first issue published in 2022 and will
include four issues.
CARSTENS, J. D. 2021. BUILDING A COMPREHENSIVE PLANT COLLECTION. ARNOLDIA, 78(3): 2–4
Building a Comprehensive Plant Collection
Jeffrey D. Carstens
B
uilding a germplasm collection can take McCoy connected me with Marty Silver, a
years or, more realistically, even multiple park ranger at Warriors’ Path State Park, who
careers to assemble. The United States graciously volunteered to help. Silver stated
National Plant Germplasm System has nine- he had “limited botanical skills” and was sim-
teen stations around the country, and the goal ply an “interested amateur botanist spending
is to acquire, conserve, evaluate, and distribute spare time in the field in various wild places
genetically diverse plant material. As a gene- in Tennessee.” To ensure initial success, we
bank curator at the North Central Regional selected Monarda didyma as the target from
Plant Introduction Station in Ames, Iowa, I’m eastern Tennessee, since we had no holdings
responsible for managing collections of woody of the species from the region. The species also
plants like ashes (Fraxinus) and chokeberries displays very conspicuous red flowers from
(Aronia), and also herbaceous plants. The col- July through August and is somewhat ubiqui-
lections arise from plant exploration by staff tous in the target area. This would make the
members (I typically make at least five col- plants relatively easy to locate. By the end of
lection trips per year), through exchange with August 2018, Silver had documented several
other genebanks or public gardens, or by spe- flowering patches of M. didyma, and that fall,
cific arrangements between a curator and an he returned and successfully collected seed
independent collector. The latter became more (accession Ames 34356). Despite living approx-
important than ever in 2020, as the coronavirus imately an hour away from the sampling site,
pandemic restrictions prevented normal travel. Silver conducted this travel and exploration on
One of our most notable collections from a volunteer basis.
this unusual season occurred in the mountains As Silver and I communicated after the 2018
of northeastern Tennessee. The story, however, collection, he drew my attention to a very
began in June of 2018, when I sent an email to thorough floristic survey of the nearby Rocky
Roger McCoy, the director of the Tennessee Fork Tract, written by Foster Levy and Elaine
Division of Natural Areas, looking for con- Walker, published in 2016. Silver connected me
tacts in eastern Tennessee who might be able with Levy, who brought our attention to several
and willing to collect native Monarda species. Monarda specimens from the area that were
Monarda, or the bee balms, is a group of her- labeled M. × media, a taxon that was missing
baceous plants native to North America and within our germplasm collection. We desig-
Mexico and is represented by approximately nated this hybrid as our next target.
eighteen species. Our Monarda germplasm Monarda × media is of potential interest for
collection in Ames currently includes four- development as an ornamental landscape plant.
teen species, represented by 164 accessions. Moreover, when I reviewed the published litera-
In the last couple of years, we’ve acquired ture and herbarium specimens, I found a curious
interesting samples, including three species backstory for the taxon, suggesting that well-
that were first described by botanists within documented wild collections could also support
the past decade: M. luteola, found in north- taxonomic research. The taxon was described
eastern Texas and southwestern Arkansas; M. over two hundred years ago, in 1809, by the
austroappalachiana, endemic to the Southern German botanist Carl Ludwig Willdenow, who
Appalachians; and M. brevis, a dwarf, early- published the name without the multiplication
flowering species found in West Virginia and symbol. The symbol is used to indicate plants
historically in Virginia. of hybrid origin, although it is not required in
Facing page: Collaboration is key for developing a plant germplasm collection. A recent seed
collection of Monarda × media in northeastern Tennessee is a case in point.
PLANT PHOTOS BY MARTY SILVER; SEEDS BY ASHLEY SONNER, USDA ARS NCRPIS
Monarda 3
4 Arnoldia 78/3 • February 2021
a taxonomic name nor does authorship change the field as an opportunity to be completely
in the event a name is later recognized as a distanced while regaining a sense of normalcy.
hybrid. While Willdenow’s description does Using Levy’s herbarium vouchers, we identi-
not suggest that he recognized this taxon as a fied a total of three potential sites, but since
hybrid, he nonetheless noted an affinity to M. the specimens were described from a broad geo-
fistulosa, commonly known as wild bergamot. graphic area, their relocation was going to be
By 1901, Merritt Fernald, a botanist at Harvard, challenging. A few weeks later, Silver reported
described observing numerous intermediate finding Monarda × media while on a hike on his
forms of M. media, making separation from day off. His hike to get to these populations was
M. fistulosa difficult. three and a half miles (one way) with an eleva-
Currently, Monarda × media is recognized tion climb of over two thousand feet. He took
as a variable group of plants with intermedi- notes, GPS coordinates, and photos. Making
ate characteristics of M. didyma and either the hike once again in the fall, Silver relocated
M. fistulosa or M. clinopodia or both. These the five previously flagged flowering patches,
numerous intermediate forms may stem from but one patch had been completely destroyed
the various hybrid combinations, and thus, the and another patch was nearly decimated due
name M. × media should ultimately be assigned to human disturbance. He collected seeds from
to a specific combination (for instance, M. the available patches and then shipped them
didyma crossed with M. clinopodia), with new to Iowa. I assigned them an accession num-
names given to each of the others. Surprisingly, ber (Ames 35579) and deposited them into the
Willdenow did not designate a type herbarium repository’s freezer, which maintains the seeds
specimen, which could make it more difficult at 0°F (-18°C). This collection will be periodi-
to determine which combination should, in cally monitored for viability, and when ger-
fact, retain the original name. mination falls below a critical level, it will be
To correctly sample true-to-type specimens regenerated using controlled pollination tech-
of Monarda × media in nature, Silver would niques ensuring the preservation of the genetic
need to mark populations in bloom, since M. profile for the future. Since Silver sampled each
clinopodia—a white-flowered species—and clonal patch separately along with appropri-
M. didyma are often found nearby; sometimes ate plant descriptions, the collections will be
they are even intermixed with M. × media. This important resources for future research (includ-
raises an interesting question about whether ing ecogeographic and phylogenetic studies).
M. × media plants are stable in nature or The collections might also be useful for select-
ing superior genotypes for the nursery industry.
whether they require the parents to constantly
Having one collection of this taxon is, of
resupply them. Despite subsequent discussion
course, only a start—additional samples are
about conducting reconnaissance and sampling
desired. Yet Silver’s collections demonstrate
for M. × media in 2019, Silver had other projects
the critical importance of local assistance while
that left no time to acquire samples.
assembling a comprehensive germplasm collec-
The following year, as implications of the
tion, especially given the amount of time and
coronavirus pandemic were becoming clear, I
effort required to acquire even a single collec-
followed up by asking about the possibility of
tion. In the end, I’ll never forget Silver humbly
sampling a Monarda × media population. Sil-
labeling himself as an “amateur botanist with
ver quickly replied, “I am much more out and limited taxonomic skills,” as his Monarda ×
about in the field (outside and distanced) these media collection is one of the most exciting,
days. If pointed in the right direction, I’ll be glad well-documented samples of Monarda that I’ve
to try and find populations within my limited accessioned in my nearly twenty-year career.
taxonomic skills.” While the pandemic quickly
resulted in travel cancellations and restrictions Jeffrey D. Carstens is the curator for woody and
(out of state, not to mention out of the coun- herbaceous plants at the North Central Regional Plant
try) across many agencies, Silver saw being in Introduction Station.
DAVID GREENBERGER
A Conservation SOS: Polygonum hickmanii
Holly Forbes
P
lants with less-than-showy flowers tend coalition called California Plant Rescue. Each
to get overlooked, even by some of the year we make an ambitious plan for conserva-
sharpest botanists. When a plant is only tion fieldwork in the greater San Francisco Bay
a few centimeters tall and flowers later in the Area, and for 2020, we planned a packed calen-
season than its more eye-catching neighbors, it dar. Most of our fieldwork was derailed by the
can be even easier to miss. The Scotts Valley restrictions put in place to limit the spread of
polygonum (Polygonum hickmanii) is a case COVID-19, especially given the timing of the
in point. This tiny species was first described restrictions. Annuals and herbaceous perenni-
in 1995 and was already very rare. It occurs als on California’s Central Coast tend to have
in a limited urban area in Scotts Valley, near a short spring cycle of growth and seed set. By
Santa Cruz, California, where it is under pres- the time permission was given to be in the field
sure from development. Only 2,100 plants were for just day trips, seeds had already set and been
observed in 1997, and in 2003, the United States dispersed for many species.
Fish and Wildlife Service listed it as endangered Scotts Valley polygonum, in contrast, is
under the federal Endangered Species Act. an annual wildflower that typically starts to
As the curator of the University of California germinate in December, flower from May to
Botanical Garden at Berkeley, I work with the August, and set seeds in August. The species
national Center for Plant Conservation and a is now known to occur on less than an acre of
In recent years, the endangered Scotts Valley polygonum (above) has been observed in only one wild population.
FORBES, H. 2021. A CONSERVATION SOS: POLYGONUM HICKMANII. ARNOLDIA, 78(3): 5–6
6 Arnoldia 78/3 • February 2021 private land adjacent to a new housing develop- ing through September 22. The evacuation zone ment. The development company established a included the two historic polygonum sites. The conservation easement to protect Scotts Valley only extant site, from which the seeds had been polygonum and another endangered species, collected, was on the margin of the evacuation Scotts Valley spineflower (Chorizanthe robusta zone, just across a four-lane highway. It could var. hartwegii). Both species are in the buck- have easily been different. The fire burned so wheat family (Polygonaceae). In 2015, no Scotts hot in places that any seeds present in the soil Valley polygonum were found at this site, and were cooked. During the fire we anxiously it wasn’t until 2020 that the number of plants checked the maps. It was a great relief to learn went above four hundred, less than 25 percent that the polygonum sites did not burn. of the population observed in 1997. Our purpose for collecting seeds was two- In the past, Scotts Valley polygonum has been fold: first, to create a conservation seed bank documented at two nearby locations, but no as a backup in case the population is lost for specimens have been observed there in recent any reason, and second, to produce more seeds years. One of these locations is a special eco- by growing plants in a nursery environment. logical preserve adjacent to Scotts Valley High This amplification of seed numbers may make School, where the polygonum has not been it possible both to reestablish the plants at their observed since 2015. The site is fenced and historic sites and to augment the numbers of managed to support the species, but we have plants within the conservation easement. limited hope it will reappear on its own. In November, propagator Susan Malisch at When my colleagues and I could finally the University of California Botanical Garden return to the field, pandemic protocols required sowed one-third of the polygonum seeds from all participants to travel solo in vehicles and our seedbank. As of late January 2021, over 85 to maintain at least a six-foot distance from percent germination has been observed. Each one another when working at the sites. I was seed was sown individually to minimize root fortunate to work with two other botanists, disturbance when the plants are moved into Kathy Lyons and Jaymee Marty, at the easement larger containers. The plants aren’t likely to site on August 7. We declared ourselves free grow larger than six inches tall and perhaps two of COVID-19 symptoms and signed liability inches across—giants compared to the plants in waivers for the landowner. The plants occupied habitat, where they are crowded together and an area of less than forty square feet, scattered typically grow about one and a half inches tall. across an undulating grassland. We worked for We look forward to a successful crop of hours on hands and knees making a modest Scotts Valley polygonum in 2021. If all goes as seed collection from the less than five hundred planned, we will have thousands of seeds to use plants—all that is left in the world. in saving this species from extinction. Wildfires As we collected the tiny seeds from the plants and other threats still pose an incredible risk (removing only a small percentage of the seed to the species, but with a robust conservation set), we remarked on how it almost felt normal seedbank and the knowledge of how to grow the to be in the field again, despite the pandemic. plants to reproductive size, we can safeguard Travel restrictions had resulted in a huge reduc- its future. Botanists are paying close attention, tion in the number of cars on the road, which and Scotts Valley polygonum is no longer over- meant that, as a side benefit, travel between looked. Next November, we plan to work with Berkeley and Scotts Valley flowed along at the the federal Recovery Implementation Team— speed limit, instead of crawling through typical a team established by the Fish and Wildlife Silicon Valley gridlock. Travel each way took Service—to place seeds back into the habitat. one hour instead of the usual three. A few weeks after our work, the CZU Light- Holly Forbes is the curator of the University of California ning Complex wildfire in Santa Cruz and San Botanical Garden at Berkeley. Support for the Scotts Mateo Counties blackened over eighty-six thou- Valley polygonum project is provided by the Ventura sand acres, starting on August 16 and continu- Office of the United States Fish and Wildlife Service.
ENZENBACHER, T. 2021. AN UNUSUAL AUTUMN AT THE DANA GREENHOUSES. ARNOLDIA, 78(3): 7–9
An Unusual Autumn at the Dana Greenhouses
Tiffany Enzenbacher
O
ctober was quiet. The headhouse at the This annual activity has occurred at an
Dana Greenhouses was still, except invigorated level since 2015, when the Arbo-
for the dim hum of the radio, a neces- retum launched the Campaign for the Living
sity for an almost empty building. In previ- Collections, a strategic ten-year initiative to
ous years, the same location would have been increase the biodiversity and conservation hold-
marked with a cacophony of sounds, the door ings of our living collections by adding nearly
thrown ajar as Arnold Arboretum plant collec- four hundred wild-collected taxa that were not
tors eagerly arrived to unpack their hard-earned already growing in our landscape. As part of
seeds and plants. Sieves and colanders would the campaign, staff organized and executed as
have rattled against the center worktable as many as five expeditions annually, traveling to
plant production staff removed fruit pulp from locations in northern Idaho, central China, the
each seed, and everyone would be talking about country of Georgia, and elsewhere.
new and exciting acquisitions. Seed cataloging I have participated in two of those expedi-
and cleaning is a departmental undertaking, tions myself: one to the Ozarks and another to
sometimes lasting the entirety of fall and into northern Illinois and Wisconsin. It was reward-
early winter. ing to engage in the full process, from planning
TIFFANY ENZENBACHER
The pandemic changed fall and winter routines at the Dana Greenhouses, providing an unplanned reprieve from processing new,
wild-collected plant material. Chris Copeland (above) prepares grafts of a plum (Prunus alleghaniensis), one of hundreds of clonal
propagations that are completed annually.
8 Arnoldia 78/3 • February 2021
expedition logistics and obtaining permits to prises scattered populations on the Delmarva
harvesting in the field and then processing seed Peninsula of Delaware and Maryland.) For me,
back at the Dana Greenhouses. The collection this collection brought home the purpose of
that stands out most from my two experiences the campaign and the urgency of preserving
was of the endangered seaside alder (Alnus threatened taxa.
maritima ssp. oklahomensis). I collaborated In the fall of 2020, however, those collections
with Kea Woodruff, then the Arboretum’s plant ceased due to the pandemic. Planned expedi-
growth facilities manager, to collect seed from tions to China, Japan, and South Korea were
two plants growing along the Blue River in postponed. In the headhouse of the Dana Green-
Tishomingo, Oklahoma. We were guided by houses, the difference was striking. Only two or
local experts. This subspecies of the seaside three members of the plant production depart-
alder has only been documented in three other ment worked on-site on any given weekday, in
locations in the wild, all near the Blue River. an effort to de-densify our workspace and to
(The two other subspecies also have extremely allow staff to care for children who were com-
restricted ranges—one occurs in a single loca- pleting schoolwork from home. This revised
tion in northwestern Georgia, the other com- schedule continues into the new year. Other
TIFFANY ENZENBACHER
When new plant material arrives at the Dana Greenhouses, staff begin a detailed process of record keeping. New innovations have
streamlined the process. Sean Halloran (above) readies softwood cuttings and will note rooting observations using a newly devel-
oped mobile application in spring.Dana Greenhouses 9 nonessential staff are not permitted inside the our plant propagator, had to transport boxes building. Now, our team hears only the quiet of binders to and from his home as he toggled sounds of greenhouse doors opening as we between remote and on-site work this spring. check the facilities, monitor plants for water, Our team has also completed work that will and scout for insect pests and diseases. We hear help us to map, track, and communicate about the clatter of containers being placed on potting plants in our nurseries using additional Land- benches as we prepare to transplant seedlings scape Management System tools. Chris Cope- and the swish of cutting media components land, our greenhouse horticulturist, worked being mixed as we get ready for winter hard- with members of the Landscape Management wood cutting season. We occasionally share the System team to acquire and upload locations of same workspace, but only brief, work-related over 250 nursery plants. Specimens are now vis- interactions can take place. Our team meetings ible on a dynamic map, and we can easily pic- are now virtual. ture spatial patterns and adjust maintenance of The production cycle for plants already in the the next generation of Arboretum plants. Like- greenhouses and nurseries has not significantly wise, when horticulture staff inherit a tree after slowed this year, although the headhouse tables it has been transplanted into the landscape, are bare: no collection sheets from the expedi- they can use this new set of tools to determine tions strewn about, no bags of fermenting berries noteworthy events that transpired during the or cones to go through. During this altered time, tree’s early life. as we have continued with usual greenhouse and We are also working with Mike O’Neal, the nursery tasks, the plant production department director of BG-BASE, to analyze information has had the opportunity to refocus our direction about our repropagation attempts. Each year on other activities. We have made enormous we duplicate hundreds of historic Arboretum strides to integrate our workflows into the Land- plants through vegetative propagation—a pro- scape Management System, a new digital tool cess whereby resulting progeny are genetically developed at the Arboretum, which combines identical to the original. Halloran and O’Neal horticulture and curation efforts through mobile are in the process of creating BG-BASE sum- applications and an internal website. mary reports. The result will help determine One component of this system, PropMan- whether the repropagation of a specimen in ager, will eventually replace the use of hand- the landscape is complete. Instead of Halloran written propagation cards, which are used to spending weeks at his desk writing code and record treatments and results for propagation manually sleuthing through BG-BASE tables, attempts, including for seeds that return from he will be able to run a quick query to have expeditions. Currently, when seeds arrive, staff access to all the data needed. record propagation methods and experiments The scene at the Dana Greenhouse is certainly on these cards. While some seeds can be sown different than it was in autumn 2019. That year, immediately, others must undergo periods of we processed over 150 seedlots and mailed surplus cold or warmth. Others require treatments to material to over a dozen collaborating institu- weaken the seedcoat: sandpaper or an acidic tions. Yet the unplanned reprieve from receiving solution. Data from propagation cards are then campaign material has allowed our plant produc- entered into BG-BASE, the Arboretum’s plant tion team to collaborate on projects that would records database. Then, as germination, trans- have otherwise progressed incrementally over planting, and other events occur, the cards are multiple years. We are now better equipped than updated, corresponding data are input into BG- ever and prepared for the onslaught of new seed BASE, and the cards are refiled into a binder. collected by Arboretum explorers who are eager PropManager will allow us to create a digital to be back out in the field. “card” on a mobile device and record events in real time. We observed how inefficient the Tiffany Enzenbacher is manager of plant production at the physical card system was when Sean Halloran, Arnold Arboretum.
FREI, J. 2021. A BRIEF HISTORY OF JUGLANDACEAE. ARNOLDIA, 78(3): 10–17
A Brief History of Juglandaceae
Jonas Frei
W
hen I first encountered butternuts on found growing as lone specimens on farms. But
the ground of the arboretum here in the number of these solitary trees has declined
Zürich, Switzerland, I was puzzled. in the region since the industrialization of agri-
The tree these nuts fell from must have died culture half a century ago. Walnut farms and
or been felled years ago, so I only had the seeds orchards are relatively new in the German-
for identification. This North American spe- speaking part of Europe, and walnuts bought
cies, Juglans cinerea, is rarely seen in European in grocery stores here mostly originate from
cultivation outside specialized tree collections, France (Périgord and Grenoble), the United
and I didn’t recognize the ridged, oblong nuts. States (California), or Chile.
When I took a few home, they were not easy to Members of Juglandaceae, however, were
identify within books on common park trees. once among the most common trees of allu-
After additional research, however, the butter- vial forests in Central Europe. Fossils allow us
nut aroused my fascination and left me with to look back on a plant family whose greatest
questions about the whole walnut family (Jug- diversity and distribution preceded the ice ages
landaceae). I had long been familiar with this in the Paleogene and Neogene. Many species
group of plants, but the more I read about them, disappeared only a few hundred thousand years
the more I realized that, in fact, I knew so little. ago. I became fascinated by this history. The
Like the butternut, many other members of fossil record reveals a long, slow story of evo-
the walnut family were absent in books that lution and shifting ranges, and it provides a
I had at home: hickories (Carya), wingnuts counterpoint to the story of the family’s rapid
(Pterocarya), and platycarya (Platycarya). As I globalization in recent centuries.
encountered each new species, new questions Not far from Strasbourg, in the Rhine Val-
arose. After several years of intensive study, ley of France, researchers and fossil collectors
my pursuit evolved into a book project, Die have discovered fossilized butternuts, described
Walnuss, which was published (in a German under the name of Juglans bergomensis. These
edition) in late 2019. My work with this unique fossils correspond so closely to the North
plant family went far beyond scientific analy- American butternut that it is hard to find
sis; it also involved an artistic exploration of visual differences. The nuts must have fallen
the unique variety of forms of this plant fam- into the shallow water and sandy substrate of
ily. I wanted to make the knowledge hidden in the Rhine five million years ago, but they still
scientific papers accessible through a language have almost the weight and feel of fresh nuts
of drawings and photographs. These differ- due to carbonization. In fact, this species had a
ent approaches—science and art—offered new wide distribution: its fossils have been reported
ways of observing and understanding the world in Italy, the Netherlands, and wider parts
of walnuts. of eastern Europe and Russia. Similar fossils
dating to the Neogene have been found in
∫
I live in a region with no native species of this Japan and in the southern United States. Fossil-
widespread plant family. Here, you can occa- ized hickory nuts are also present in the Rhine
sionally find the North American eastern black sediments, including those of a widespread
walnut (Juglans nigra) planted as an ornamental fossil taxon called Carya globosa, which is sim-
tree in parks. The English walnut (Juglans regia) ilar in appearance to the water hickory (Carya
was most likely introduced by the Romans into aquatica). Although all the European hickory
the northern parts of Europe and can often be species went extinct millions of years ago,
Facing page: The walnut family is best known for nut-bearing species like the English walnut (Juglans regia), pictured
here in the Thur Valley of Switzerland, but the family also includes notable wind-dispersed species.
ALL IMAGES BY THE AUTHOR12 Arnoldia 78/3 • February 2021 the nuts look as fresh as if they were only a few cies could migrate according to climate condi- years old. tions, many European species died out with Walnut family species with large, animal- every cooling and warming. The fossil record dispersed fruits are only part of the story. Wing- indicates that wingnuts survived this back and nuts (Pterocarya)—a genus that is now known forth the longest of all Juglandaceae, but in the for six extant species—were once dominant end, they vanished irretrievably, just like the trees here in Central Europe along rivers and in European magnolias (Magnolia), kiwis (Actin- mountain slope forests. These are ancestors of idia), and sweetgum (Liquidambar). Other gen- the species we now call the Caucasian wingnut era of woody plants, including maples (Acer) (P. fraxinifolia), which today runs wild in parks and ashes (Fraxinus), are now represented in and gardens in Central Europe, its root sprouts Europe with only a few species but had much forming dense stands. Some horticulturists greater diversity before the Pleistocene ice ages have argued that we should cease planting this that started about two and a half million years species in our gardens, given these invasive ago. The diversity of these genera in Europe was tendencies, but based on the fossil record, we similar to their modern-day representation in could also view the wingnut as a returnee from North America and Asia. another era. After all, wingnut leaf fossils in The fossils reveal more than former distri- the Stuttgart region were found in sediments butions and long-extinct species—the record of the Holstein interglacial and date back only also documents how the walnut family evolved 325,000 years. The few remaining populations from an entirely wind-dispersed family to one of this once widely distributed species are with the charismatic nut-bearing species that increasingly threatened in their last refuges in we know today. Some of the oldest fossils of the Caucasus. Wheel wingnuts (Cyclocarya) Juglandaceae fruits originate from the United and platycarya—both unusual wind-dispersed States. Fruits of a wheel wingnut named Cyc- genera now found only in East Asia—are also locarya brownii have been found in different represented in the fossil records in Europe. sites from the Paleocene, occurring shortly The reason the walnut family went extinct in after the K-T boundary, the geologic marker Europe while some species meanwhile survived that separated the Cretaceous and Paleogene a in North America and East Asia is related to good sixty-five million years ago. This event of the geographical shape of the continents. Here mass extinction was both the end of the era in Europe, the Alps and the Mediterranean Sea of dinosaurs and ammonites and the beginning form a barrier for the north-south migration of a new chapter for the walnut family. of plant species. In cold periods, trees could Cyclocarya looks very typical for early mem- survive only in the southernmost corners of bers of the family, especially since its fruits are Europe; therefore, while in America plant spe- spread by the wind and not by birds or mam- Fossils document the former abundance of the walnut family in Central Europe, where no members of the family naturally occur today. Hickory (Carya) fossils, shown above, were collected from sediments in the Rhine Valley, close to Strasbourg, France, and are around five million years old.
Juglandaceae 13
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m
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The author’s illustrations show both the diversity and beauty of the walnut family: (a) English walnut,
Juglans regia; (b) little walnut, J. microcarpa; (c) Japanese wingnut, Pterocarya rhoifolia; (d) Japanese
heartnut, J. ailantifolia var. cordiformis; (e) black walnut, J. nigra; (f) butternut, J. cinerea; (g) Arizona
walnut, J. major; (h) Platycarya strobilacea; (i) Ma walnut, J. hopeiensis; (j) Manchurian walnut, J. man-
dshurica; (k) nutmeg hickory, Carya myristiciformis; (l) buart hybrid, J. × bixbyi; (m) Chinese butternut,
J. cathayensis; (n) bitternut, C. cordiformis; and (o) Chinese wingnut, Pterocarya stenoptera.14 Arnoldia 78/3 • February 2021
mals. Back in Paleocene, some fifty million
∫
years ago, mammals only started to special- Today, in Central Europe, almost forty species
ize in the new ecological niches that became and hybrids of Juglandaceae are cultivated. Dur-
available after the extinction of the dinosaurs. ing my research, I traveled to many parks and
Many other winged walnut species emerged. arboreta, looking for insight into the diversity
Some went extinct, but the descendants of oth- of this family. I was driven not only by my
ers are now populating the tropics of the New scientific interest in Juglandaceae but also by
and Old World: Oreomunnea in Central and my enthusiasm for the aesthetics of their hab-
South America, and Engelhardia in Southeast its, leaves, and fruits. The readers of my book
Asia and northern India. It was only with the should be able to make their own journey of
diversification of mammals, especially squir- discovery through the walnut family, on the
rels, that some walnut species developed fruits tracks I have uncovered with my research.
that could be spread by animals. Often, after days of traveling, I would find out
Squirrels and other rodents drove the evolu- that a tree I wanted to visit had been cut down
tion of Juglandaceae in two different genera: or that a rare species was simply confused with
walnuts (Juglans) and hickories (Carya), which an ordinary, oft-planted one. I created a collec-
evolved within separate lineages. Birds, espe- tion of seeds of all the cultivated species and a
cially the crow family, likely played a part in leaf herbarium. The collection soon included
the distribution from the beginning as well. hundreds of fruits and nuts from different loca-
Because animals never find all the nuts they tions in Europe, which made it possible to dis-
stash in their winter storage places, they con- tinguish between the species and hybrids. Later,
tributed to the spread of these groups, and evi- the collection became the basis for the illustra-
dently, they were quite efficient. Walnuts and tions of all species in the individual portraits
hickories spread through North America, Asia, of the book.
and Europe, populating much of the Northern These trips through Europe searching for
Hemisphere. In the case of the walnuts, this pro- the different species of the walnut family also
cess must have taken place during the span of brought to light the stories of other humans—
about ten million years. The oldest known fos- botanists and horticulturists—who moved the
sil record of the genus, a species named Juglans walnut family all over the world. While I could
clarnensis, was discovered in North America find many species within a day or two of search-
and dates back forty-four million years, while ing, many researchers spent years traveling
the oldest European specimen of J. bergomensis through the natural habitats in North America
is around thirty-three million years old. and Asia a few centuries ago. In the time of
Later, humans helped with the worldwide Carl Linnaeus, only three walnut species were
spread of two major species: the English walnut known to European researchers. Besides the
and the pecan (Carya illinoinensis). Whereas English walnut, Linnaeus included the North
squirrels and crows spread walnuts and hicko- American butternut and the eastern black
ries on three continents over several million walnut in his Species Plantarum, published
years, humans extended the range of cultivation in 1753. The hickories—especially the Asian
into all other suitable climatic regions within species—were documented much later.
a few decades. The English walnut (a species The genus name Carya was proposed by the
of Eurasian origin) and pecan (from the south- English botanist and plant collector Thomas
eastern United States) are now cultivated well Nuttall, who used the name, in 1818, in his work
outside their native range, including in parts of The Genera of North American Plants. He had
South America, northern and southern Africa, borrowed this name from ancient Greek, where
Australia, and New Zealand. So, the tasty ker- karya was a word for walnut. The valid botani-
nels of the walnut became the main reason for cal name for a genus or species should always be
this widespread distribution—a process started the one from the first official description, and
by squirrels many millions of years before the in this case, Nuttall’s proposal wrongly became
fossil records prove the evolution of humans. the namesake of the genus. Ten years earlier,Juglandaceae 15
a
b
c
e
d
f
g
i
h j
k
m
l
The large kernels of walnuts and hickories have inspired animals to disperse the species widely: (a) English walnut
(cultivar), Juglans regia; (b) water hickory, Carya aquatica; (c) shellbark, C. laciniosa; (d) Chinese hickory, C. catha-
yensis; (e) bitternut, C. cordiformis; (f, g, h) English walnut (cultivars); (i) butternut, J. cinerea; (j) black walnut, J. nigra;
(k) Japanese walnut, J. ailantifolia; (l) Japanese heartnut, J. ailantifolia var. cordiformis; and (m) pecan, C. illinoinensis.
the hickories were described under the name whereas Hicoria is derived from the Algonquin
Hicoria by the American polymath Constan- word for a well-known hickory dish: pocohi-
tine Rafinesque. These circumstances led vari- quara. That name reveals an obvious fact: these
ous scientists to urge for reinstating the earlier trees have a cultural importance that far pre-
name, but the change was never implemented. dates their scientific documentation.
It would have been a respectful act, not only to Philipp Franz von Siebold was one of the first
honor the scientific rules but also because the Europeans to collect plants in Japan. One of
Greek word karya refers to the English walnut his great collections was Platycarya strobila-16 Arnoldia 78/3 • February 2021
cea, which was described in 1843. Some bota- that formed in the western United States due
nists initially thought it was a conifer due to to the proximity of the eastern black walnuts,
its cone-like fruiting structures. In 1844, the cultivated in parks, and natural populations of
famous English plant collector Robert Fortune the Arizona walnut (Juglans major). And the
also found Platycarya in China. Assuming that walnut fruit fly (Rhagoletis completa), which
it was a new, not-yet-described species, he sent once lived inconspicuously on the black wal-
herbarium material and seeds to the Royal Hor- nut species of North America, today spreads
ticultural Society in London. John Lindley, the quickly in walnut orchards of Europe.
secretary of the society, named the plant after Meanwhile, the close planting of related
its finder, Fortunaea chinensis, and called the Juglandaceae species leads to the formation of
species the most important new find of For- hybrid offspring. This has led to major changes
tune. Later, it became known that Siebold had in natural environments, especially in the case
described the species one year earlier, so today of the butternut populations in North America.
the name Fortunaea is only used as a synonym. Many of the butternut trees that can resist the
These scientific explorations—and those of butternut canker also carry the genetic material
other botanists—made it possible to describe, of Japanese walnuts (Juglans ailantifolia). Resis-
collect, and, of course, cultivate many of the tant hybrids have greater fitness, as they sur-
species as ornamentals and orchard trees. But vive and have more offspring, which could be a
this era of Siebold and Fortune was not sim- blessing for the American butternut stocks that
ply a time of great scientific discovery; it was survive the strong fungal infestation. On the
also a time of European colonization, in which other hand, conservation of the “real” butter-
the gathering of knowledge on expeditions was nut becomes more complicated. This scenario
often combined with ideological, cultural, and reveals the cascade of unintended but profound
religious imperialism. This movement of plants environmental consequences of human actions,
around the world coincided with violations which cannot be easily resolved.
of ethical standards by European maritime pow- Of course, the walnut family experienced
ers and a merciless approach to other cultures. various climatic changes over the past fifty mil-
The relatively slow but efficient distribution lion years and therefore changed its distribution
of Juglandaceae by squirrels and mice seems again and again. It is assumed that many of the
innocent in comparison. species we know today are the result of hybrid-
ization between different populations that col-
∫
When the walnut family is viewed in the broad lided after a long separation due to climatic
sweep of its evolutionary history, the speed of fluctuations and subsequent spread by squirrels
its recent spread is clearly unprecedented. As and ravens. Genetic studies suggest that the
beautiful as it is to see the worldwide diversity English walnut originated from the hybridiza-
of Juglandaceae close together in many parks tion of the black walnuts (section Rhysocaryon)
today, the globalization of the family has also and Asian butternuts (section Cardiocaryon).
produced novel threats. Also, the American butternut is said to carry
As humans moved the walnut family around some black walnut genes in addition to the
the world, fungi and pathogens often migrated genetic material of similar Asian species from
with the species. In the United States, a fungal the Cardiocaryon section. Given this history,
disease known as the butternut canker (Siro- one could say that many walnuts, as a lineage,
coccus clavigignenti-juglandacearum) has will adapt to human-made influences, although
brought the butternut to the brink of disap- it is unlikely all of the walnut species we know
pearance. The fungus, which was once native today will survive the pressure.
to Asian walnut species, causes little damage
∫
to its original hosts, but it is often fatal to the Recently, in a second-hand bookstore, I found
North American butternut. The thousand can- a small booklet titled Die Quaianlagen von
kers disease, meanwhile, is the result of the Zürich, from 1889. The author, botanist Carl
unfortunate encounter of a fungus (Geosmithia Joseph Schröter, planned the tree collection at
morbida) and a beetle (Pityophthorus juglandis) the arboretum where I first encountered theJuglandaceae 17
The author’s book Die Walnuss—currently available in a German-language edition—features drawings, photographs, and
descriptions of the walnut family.
butternuts that started my interest in this cination how some species emerge from this
exceptional plant family. He states that a but- immense pressure and how others disappear,
ternut tree was planted in 1887 at exactly the just like during the whole history of this fam-
spot where I found the nuts pressed into the ily. But we also have a responsibility towards
soil. Now I know that these nuts, almost like biodiversity, towards those species that exist
modern-day fossils, are the remains of a now- now and that enriched the global ecosystem
rare species. The tree was planted long before long before the arrival of humans. Today, as the
butternut canker was imported to the United pace of ecological change and movement con-
States, and before hybridization with imported tinues to accelerate, we have to recognize that
species changed its natural populations rapidly. the story of the walnut family is now entwined
If we did not have our own hands in all the with our own.
processes that threaten species like the butter-
nut, we could analyze the consequences from Jonas D. Frei is a landscape architect, documentary film-
a scientific perspective and see with great fas- maker, illustrator, and author from Zürich, Switzerland.COFFMAN, G. C. 2021. DISCOVERING THE MAJESTIC MAI HING SAM OF LAOS. ARNOLDIA, 78(3): 18–27
Discovering the Majestic Mai Hing Sam of Laos
Gretchen C. Coffman
I
n early April 2007, less than three weeks only old-growth specimens in the world, and
after submitting my dissertation and receiv- in recent years, the stands have been increas-
ing my doctorate at the University of Cali- ingly threatened by agricultural development
fornia, Los Angeles, I got on a plane headed for and poaching for the luxury timber market. The
Laos. It took four flights and more than twenty protection of the few hundred remaining indi-
hours of flying time to get to the capital city viduals in Laos has become my mission.
of Vientiane. From there, I was bound for the
Annamite Mountains: an eight-hour drive from Arriving in Laos
Vientiane, then onward by truck, hand tractor My journey to the Annamite Mountains had
(tok tok), and boat. begun four months earlier, when a member of
The remote Annamite Mountains run 680 my doctoral committee, Phil Rundel, emailed
miles (1,100 kilometers) along the border me with a proposal to work on a project in an
between Vietnam and Laos, reaching into north- especially remote part of Laos. I was imme-
ern Cambodia. This range divides the Mekong diately intrigued by the biodiversity, and the
River Basin to the west from Vietnam’s nar- thought of getting away from my computer days
row coastal plain to the east. The mountains after finishing my dissertation was alluring. Yet,
are home to exceptional biodiversity. After the I was hesitant. The opportunity involved work-
Vietnam War ended, Laos closed to Western- ing as a restoration ecologist on a World Bank
ers, but in the early 1990s, the borders began to hydropower project. As a wetland and riparian
open. Biologists began to document fascinating ecologist by training, I had always focused my
endemic wildlife, some new to science, includ- research and professional work on protecting
ing the enigmatic saola (Pseudoryx nghetinhen- rivers and streams, not damming them.
sis), a critically endangered bovine that, due to Rundel encouraged me to research both points
its rarity, has been dubbed the Asian unicorn. of view—pro- and anti-hydropower dam. On
Perhaps the most miraculous discovery was my breaks from dissertation writing that win-
that of the endangered Laos rock rat (Laonastes ter, I read articles and websites from advocates
aenigmamus), a rodent identified as a surviving and opponents (including, among the latter,
member of a family (Diatomyidae) previously International Rivers and other nongovernmen-
thought to have gone extinct about eleven mil- tal organizations). I also corresponded with
lion years ago.1 wildlife biologists who would be working on
Plant biodiversity in this mountain range is the project. The work was part of mitigation
exceptionally rich as well, and many new spe- actions for the Nam Theun 2 Hydropower Proj-
cies have been documented.2 When I initially ect and supported the development of a national
arrived in the foothills, I could not have imag- park in the reservoir’s headwaters. At more
ined that I would become part of one of these than 1,300 square miles (3,500 square kilome-
discoveries: the first biologist to collect samples ters), this protected area is one of the largest
of the majestic Asian swamp cypress (Glypto- remaining contiguous areas of forests on the
strobus pensilis) growing in the country. This Indochinese Peninsula.3
critically endangered species—locally known as Ultimately, I made a pragmatic decision:
mai hing sam—is currently documented in only there was no stopping the dam, but I could
two other heavily degraded populations, both in work for the wildlife by helping to develop a
Vietnam. The mai hing sam in Laos are the conservation plan. I would work closely with
Facing page: The author was the first researcher to document the critically endangered Asian swamp cypress, Glyptostro-
bus pensilis, growing in Laos. This old-growth specimen, photographed in 2015, is locally known as the “mother tree.”
PHOTO BY DAVID MCGUIRE20 Arnoldia 78/3 • February 2021
ASSOCIATION ANOULAK
The Annamite Mountains—known for complex topography, geography, and climate—harbor some of the most-contiguous moist
forests in Indochina.
James Maxwell, a renowned botanist from steep topography. Initially, working with Max-
Chiang Mai University in Thailand, along with well proved extremely difficult. He could not
a team of wildlife biologists from a multitude of understand why I had been hired on this project,
disciplines. Our mission was to assess wetland since all my botanical experience was in the
habitat on the Nakai Plateau—located high United States. He was standoffish and focused
within the Annamite Mountains—before it was on collecting rare wildflowers he encountered.
flooded by the reservoir. We would document As we settled into the work, however, we
the wetland vegetation and develop a wildlife bonded. He proved to be an exceptional mentor
management plan that included the restoration and friend, and in the years to come, I would
of habitat within an area known as the Nakai– stay with Maxwell and his wife in Thailand on
Nam Theun National Protected Area. Little did multiple occasions.
I know I would be acting as field coordinator Our standard workdays were reminiscent
once I arrived, a task that I was comfortable of my first fieldwork experiences in the hot,
with from fifteen years of managing restoration humid wetlands of coastal Georgia, where I had
projects in the United States but not nearly as grown up. When we arrived in Laos, it was the
easy in this new landscape and culture. height of the dry season and unbearably hot
in the late afternoons. We started at sunrise
The Discovery to avoid the heat, first eating a bowl of pho, a
The Annamite Mountains contain some of the noodle soup loaded with fragrant mint, crunchy
last relatively intact moist forests in Indochina, cabbage, long beans, and assorted leathery for-
unique due to the region’s complex geology and est leaves. In the field, we lugged our plant
climate, and relatively inaccessible due to the presses everywhere, as everything we collectedGlyptostrobus 21
ARNOLD ARBORETUM, ESRI, GARMIN, AND GIS COMMUNITY
AN
NA
M
IT
E SOUTH CHINA SEA
M
O
U
N
TA
IN
S
VIETNAM
Ro
ut
e1
Nakai–Nam Theun
3
National Park
Phou Hin Poun
National Biodiversity
Conservation Area
Nam Theun Reservoir
M
eko
ng R
iv
THAILAND
er
LAOS
25 miles
50 kilometers
Protected Areas
The author located Glyptostrobus pensilis within the Nakai–Nam Theun National Park. The discovery was made while assessing
wetland habitat and developing a wildlife management plan for the Nam Theun 2 Hydropower Project.
went immediately into the press. The after- The first potential wildlife habitat restora-
noons were sticky and oppressive in the open tion site we visited was northeast of Thousand
wetlands. We ended around four o’clock when Islands, near the Nam Xot tributary to the Nam
we couldn’t take the heat anymore, giving us Theun River. Our colleague Pierre Dubeau, a
time to process our plant specimen and clean geospatial scientist who had sited these poten-
up our notes. At that point, the plants went tial restoration areas, exuberantly walked down-
directly from the presses into rice sacks with stream through the forested wetland toward
alcohol for preservation. an area with large wetland grasses (Neyraudia
We surveyed all the herbaceous wetlands reynaudiana). Maxwell and I followed Dubeau
across the Nakai Plateau. These wetlands inter- and wildlife biologist Rob Timmins, who was
mingled with rice paddies and were often used carrying an umbrella in the sprinkling warm
as grazing pasture. We began our collections in afternoon rain. We agreed that this would be
large, easy to access wetlands on the south side a great open location, ideal for wildlife habi-
of the Nam Theun River. To guide us, we used tat restoration. As we trudged back among a
paper topographic maps. We then made our way mucky mess of the forested wetland swamp, I
to more forested wetlands and riparian forests, stumbled over something and fell to my hands
northwest towards the dam site and onward to in the soggy soils. I slowly got up, shook off
an area that was nicknamed Thousand Islands the fall, and investigated what I tripped over.
because of how the landscape flooded during It looked like a pneumatophore—the cypress
the monsoon rains. From there we continued knees I knew from my childhood in coastal
east, across the river, near the foothills of the Georgia, where bald cypress (Taxodium disti-
Annamite Mountains. chum) are a dominant feature of the swamps.Glyptostrobus 23
I looked up to find the tree it might be after in the luxury timber market and is used
attached to, and sure enough, an enormous for a variety of structural and boat-building uses
conifer towered above me. I looked up at this by local communities. It is threatened (like so
red-barked giant and saw something wonder- many endangered species) by illegal logging.
fully strange and familiar. It looked like a cross As I learned more about the two populations
between the bald cypresses that I knew from in Vietnam, I realized how remarkable the mai
Georgia and the coastal redwoods (Sequoia hing sam in Laos really were. The trees in Viet-
sempervirens) from California, both members nam grew very close together and, like those
of the cypress family (Cupressaceae). I found in China, appeared like they could have been
several other knees as I walked up to inspect planted. Boardwalks had been built within the
the tree. This, I proclaimed to Maxwell, must stands to get around. Dams located beneath
be a very special tree! Maxwell, however, like each of the stands were used for agricultural
many other tropical botanists, was not as inter- irrigation and raised the water levels for the
ested in conifers as much as the epiphytes that trees significantly. In contrast, the trees that we
might grow on them. He thought nothing of it. observed in Laos were erect and widely spaced,
Meanwhile, I collected the samples of small as expected for a wild population. The crowns
cones, foliage, and bark of this tree, which I sent of the mai hing sam in Laos were only found in
to conifer expert Philip Thomas at the Royal the top third of the trees, with no limbs below
Botanic Gardens, Edinburgh, for identification. for us to climb to the seed-bearing cones. In
the Vietnam population, perennial and annual
Documenting the Mai Hing Sam branchlets were numerous along the main
Conifers are dominant or codominant parts bole, appearing to be epicormic growth. This
of primary- and secondary-growth evergreen form suggests that the trees in Vietnam were
forests throughout the Annamite Mountains. responding to stress from inundation. Also,
In Vietnam, for instance, the mountains host some of the trees in Vietnam were cut down
a particularly rich assemblage of thirty-three years ago and had resprouted.7
conifer species, of which the cypress family I immediately told my colleagues about
(Cupressaceae) has seven.4 When I asked peo- the mai hing sam discovery so that we could
ple in the neighboring Lao communities about develop a strategy to describe and protect
the enormous tree that I had encountered, they this stand. I also informed the Nam Theun 2
provided a name: mai hing sam. Mai means Power Company (NTPC) of the discovery and
“tree,” hing is a modifier for the kind of tree, asked to spend time describing the tree and
and sam means “swamp,” or what ecologists its ecology and to have a surveyor document
would describe as a forested wetland. their elevation relative to the proposed reser-
As it turned out, the mai hing sam was, voir footprint. I was not allowed time to docu-
indeed, special. When Philip Thomas replied ment this stand properly, however, and I was
to my email, he identified the species as Glyp- only able to record the number and size of the
tostrobus pensilis (known as the Asian swamp trees and basic soil characteristics. There were
cypress), which the International Union for approximately one hundred trees in the stand,
Conservation of Nature has classified as criti- and many were three feet in diameter at breast
cally endangered.5 In 2007, the scientific com- height. We only had very rough elevation infor-
munity was aware of only 250 individuals of mation from our GPS units, but it was clear
this species in the wild in Vietnam, where most that the trees—along with many others that
were spindly, unhealthy young trees, growing we were unable to document—would likely be
in two small stands in the middle of coffee and within the reservoir footprint.
corn plantations. Other stands in China were In desperation to protect these rare trees, I
presumably planted.6 Due to its rot-resistant contacted the Nam Theun 2 Panel of Experts,
wood, Glyptostrobus pensilis is highly sought an audit group that was in charge of assessing
Facing page: Forests in the Annamite Mountains are rapidly disappearing due to forestry, agriculture, and hydropower
development, along with other causes. Philip Thomas (right) stands beside Glyptostrobus pensilis within a rice paddy.
PHOTO BY DAVID MCGUIREYou can also read
