arnoldia 
The Magazine of the Arnold Arboretum 
VOLUME 78 «© NUMBER 3 ° 2021 
Arnoldia (ISSN 0004-2633; USPS 866-100) 
is published quarterly by the Arnold Arboretum 
of Harvard University. Periodicals postage paid 
at Boston, Massachusetts. 
Annual subscriptions are $20.00 domestic or 
$25.00 international, payable in U.S. dollars. 
Subscribe and purchase back issues online at 
https://arboretum.harvard.edu/arnoldia/ or send 
orders, remittances, change-of-address notices, 
and all other subscription-related communica- 
tions to Circulation Manager, Arnoldia, Arnold 
Arboretum, 125 Arborway, Boston, MA 02130- 
3500. Telephone 617.524.1718, fax 617.524.1418, 
e-mail arnoldia@arnarb.harvard.edu 
Arnold Arboretum members receive a subscrip- 
tion to Arnoldia as a membership benefit. To 
become a member or receive more information, 
please call Wendy Krauss at 617.384.5766 or 
email wendy_krauss@harvard.edu 
Postmaster: Send address changes to 
Arnoldia Circulation Manager 
The Arnold Arboretum 
125 Arborway 
Boston, MA 02130-3500 
Jonathan Damery, Editor 
David Hakas, Editorial Intern 
Andy Winther, Designer 
Editorial Committee 
Anthony S. Aiello 
Retcr Del iredici 
Michael S. Dosmann 
William (Ned) Friedman 
Jon Hetman 
Julie Moir Messervy 
Jonathan Shaw 
Copyright © 2021. The President and 
Fellows of Harvard College 
Th ARNOLD 
ARBORETUM 
of HARVARD UNIVERSITY 
CONTENTS 
2 Building a Comprehensive Plant Collection 
Jeffrey D. Carstens 
5 A Conservation SOS: Polygonum hickmanii 
Holly Forbes 
7 An Unusual Autumn at the Dana Greenhouses 
Tiffany Enzenbacher 
10 A Brief History of Juglandaceae 
Jonas Frei 
18 Discovering the Majestic Mai Hing Sam of Laos 
Gretchen C. Coffman 
28 Backyard Climate Solutions 
Edward K. Faison 
38 A New Look at Boston Common Trees 
Kelsey Allen and W. Wyatt Oswald 
42 Case of the Anthropocene 
Jonathan Damery 
44 Planting Edo: Pinus thunbergii 
Rachel Saunders 
Front and back cover: Jonas Frei’s collection of walnut 
family fruits includes a disc-shaped wheel wingnut (Cyc- 
locarya paliurus, back cover) among other more familiar- 
looking species. Photo by Jonas Frei. 
Inside front cover: Glyptostrobus pensilis is the only living 
member of a genus that was once widespread throughout 
the Northern Hemisphere. The illustration shows a Glypto- 
strobus fossil collected near Reading, England. From Gard- 
ner, J.S. 1886. British Eocene Flora (vol. 2, part 3). London: 
Palaeontographical Society. Biodiversity Heritage Library. 
Inside back cover: The precision of It6 Jakucht’s observa- 
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 
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. 
