napcc article public garden 222 2007

8/13/2019 NAPCC Article Public Garden 222 2007

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N P OLL T I ON PROF I L

he rnold rboretu XT TMichael osmannPeter elTredici and Eric

tuated upon a 265-acre landscapeof rolling parkland and naturalwoodland, theArnoldArboretumof Harvard University contains a diverscollection of temperate woody plantsthat is both breathtakingly beautifuland scientifically significant. Founded i1872 with the lofty goal to cultivateevery tree and shrub hardy out-of-doorin Boston, Massachusetts USDAHardiness Zone 6), NorthAmerica soldest public arboretum has amassed asynoptic collection of nearly 15,000accessions representing approximately4,500 unique taxa.

TheArboretum s first director,Charles Sprague Sargent,was keenlyinterested in the floras of NorthAmeriand Eastern Asia, and the collection sstrong representation of plants fromthese regions is the result of his ownbotanical exploration as well as those ootherArboretum associates of the early th century including Ernest H WilsoJoseph Hers,Joseph Rock, andJohn GJack. Active collection developmentthrough plant exploration has continued. Recent noteworthy trips to Asiainclude the 1980 Sino-AmericanBotanical Expedition as well as severalconducted under the auspices of theNorthAmerica-China Plant ExplorationConsort ium (NACPEC), ofwhich theArboretum is a founding member.Domestic plant explorationwithinNorthAmerica has also been a significant source of plant material andcontinues to this day

Designed by Sargent in collaboratiowith landscape architect FrederickLaw Olmsted, the landscape is both anamenity pleasure ground and a researcinstitution. At its very core is the livingcollection,which is central to the fulfillment of the institution s mission todiscover and disseminate knowledgeof the plant kingdom to foster greaterunderstanding, appreciation, and


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stewardship ofthe Earth s botanicaldiversity and its essential value tohumankind: Maintained to high horticultural and curatorial standards, the collection is used for on-site research andt eaching progr ams as wel l as by externalscientists and educators. Research playsa vit al r ol e i n the enhancement of thecollection, as individual accessions arestudied, documented, and become references for future scientific endeavors.

All records are maintained in anelectronic database BG-BASE , and allplanting locations are plotted using computer-generated maps. High priority isplaced on the documentation of theliving accessions through frequent fieldchecking, the gathering and preparationof voucher herbarium specimens, andphotography.The herbarium specimens collected in vegetativeand reproductivestages) are housed in ou r on-site herbarium approximately 130,000 specimens)and are part of the Harvard UniversityHerbaria over 5 million specimens) inCambridge, Massachusetts. Such vouchering of the living collection throughtime increases its value and provides anindispensable dataset for future analyses.Should individual living plants ever bedeaccessioned, they will always remainin our collection at least in preservedform.All of our collections, living andherbarium, can be searched using onlinedatabases accessed on ou r websitewww.arboretum.harvard.edu.

N P ollectionsn2002, the ArnoldArboretum wasgiven official member status in the

NorthAmerican Plant CollectionsConsortium NAPCC) for a quintet ofgenera: Acer Carya Fagus Syringa andTsuga.The selection of these five ~based upon the current h o l d ~ s wi hinthe Arboretum s collection as we theability to achieve broad taxono

geographic diversity through additionaldevelopment.While each of the genericcollections is represented by both wildand cultivated taxa, emphasis is onbotanical taxa or known wild origin. n2006 Stewartia was added to our list,bringing the total to six. n that sameyear the Arboretum teamed up with 11other gardens and arboreta to submitan application for a multi-institutionalcollection of cer

As with all ofour collections, ourcommitment to these six genera can bedivided into three primary areas: development management, and enhancement. ndeveloping each collection further, priority is placed on obtaining newt x as well as material of documentedwild origin of taxa already held, particularly of novel geographic source.Asidefrom new material that is of cultivatedorigin and thus considered discretionary), additions to these six generarepresent a long-term, obligatory commitment. Because of their high priority,elevated attention is paid to their management including their cultivation inthe greenhouse, nurseries, and landscapeas w el l as methods to prevent the lossof historic and/or valuable lineagesthrough vegetative propagation. tis notenough, however, that the collectionsare developed and maintained: it is alsoimportant that they are enhanced.Weachieve this through documentation andresearch efforts as well as our supportof visiting researchers who us e thecollections in their work. To facilitateresearch use, we not only provide accessto the living and affiliated collections,but offer fmancial support throughfellowships and awards.

o U ~ ~ l Vouoretum s holdings reflecte of the genus within the

em Hemisphere,

particularly temperate zones ofAsia.The Acer collection comprises 133 taxawithin 55 species,with the majority ofspecimens cultivated along MeadowRoad near related genera such as Aesculusand Koelreuteria. Because of its closeness t o the administrative building andm ai n gate, it is a popular destinationpoint for visitors.

Du e to the institution s past andpresent plant explorations, maples fromEastern Asia are particularly well represented.This cohort includes the trifoliatemaples, and outstanding specimens ofAcer griseum paperbarkmaple Acertriflorum three-floweredmaple Acerm ndshuri um Manchurian maple)and Acer m ximowi zi num Nikkomaple) have prospered over the years.One of the most impressive trees inthe collection is accession 12488*B, thefirst griseum introduced to NorthAmerica. It was collected as a seedlingbyWilson in Hubei Province in 1907during isfirst x p i t i o ~ for th eArboretum.The Acer colle n h s beenused r an extensive fd l f research


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so tantalizing but the conquesteven today affords me greaterpleasure than that ofany othergroup of tr sSeveral oftheAsian taxa in our col

lection are quite rare in cultivation, andthus we frequently receive requests byresearchers and other botanical institutions to provide tissue and propagules.The beech collection also contains near20 cultivars of Esylvatica includingtwo amazing specimens of EsylvaticaTortuosa that were planted in the1880s.These individuals,with theirdome-shaped canopies of twisted andgnarled branches, are some of the mosfrequently photographed trees at theArboretum.

SyringaAmong the six NAPCC collections a

theArboretum, none is more famous

StewartiaAlthough this may be our newest

NAPCC collection, receiving memberstatus in July 2006, Stewartia is a genuwith a great deal of history at theArboretum.he oldest living accessionis a S pseudocamellia collected byWilson in 1917 in Korea.Two fme-Iooking specimens of this taxon AA 11440*and 11440*B) grow atop BusseyHillalong Chinese Path.The collection contains six other species as well as severainterspecific hybrids, varieties, and cultvars. As a research tool, this genericcollection has been used extensively bprevious and currentArboretum staffmembers; activities have ranged frommonographic and phylogenetic studiesto propagation and introduction ofornamental selections. Future work inthe development and enhancement ofthe collection will be assisted throughcollaborative efforts with nearby PollyHillArboretum on Martha sVineyard,another NAPCC holder of Stewartia.

presents the opportunity to cultivatea greater number of wild-origin provenances within each species.

agushe Arboretum s collection of Fagus

is noteworthybecause it compriseseight of the 10 to 11 species that occurin the orthern Hemisphere. Some ofthis diversity can be credited to Wilson splant-collecting efforts inAsia,wheremost of the species occur. In anunpublished manuscript on his plantintroductions (Archives of theArnoldArporetum), he describes how hem 1laged to acquire Fagus englerianaE lucida and Elongipetiolata afterprevious failed attempts:

n the spring of 1910I determinedto collect livingplants. I made aspecialjourney into north-westernHupeh and in different localitiesaffixed wire marks on about adozen seedlings of each species. Thisdone I arranged to leave in thedistrict until the autumn a manwhose sole duty was to dig up theseplants and bring them to me onmy return to changfrom westernSzechuan. He fell sick and failed tocarry ou t the trust.Winter had setin when I returned to chang bu tI determined to make a final effort.I offered two ofmy collectors whowere with me when the plantswere marked fifty ounces ofsilver they wouldjourney forth andbring in the plants. This theyaccomplishedfor the prize to themwas great. The plants wrappedcarefully in sphagnum moss andpacked in a ventilated trunkaccompanied me to thernoldArboretum where they arrived inexcellent condition. Today all threearefairly well established in cultivation. There was no special reasonwhy the identity or introduction ofthese Beeches should haveproved

projects, and now as part of the multiinstitutional NAPCCAcer group,weanticipate the collection will gain inboth distinction and utility.

aryahough easily recognized by their

large ; pinnately compound leaves, andas important silviculture crops, hickoriesare not widely represented in cultivationoutside of a few species such as Caryaovata (shagbark hickory) and Caryaillinoinensis (pecan). Because of thispaucity, theArboretum is committed tomaintaining a well-developed andenhanced generic collection.There arebetween 17 and 19 species of Carya(depending upon taxonomic treatment), of which 11 are grown at theArboretum; the collection also containsseveral botanical varieties, cultivars, andinterspecific hybrids. Species of Caryaare naturally distributed on both sidesof the Pacific, however, unlike the othergenera in the NAPCC sextet, thosegrown at theArboretum are from orthAmerica, because theAsian species areno t hardy in the Boston climate.Whilethis limits the among-species diversitytheArnold s collection can amass, it

PU LIC G RDEN


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Syringa Collection

d familiar to the average Bostonianthe lilac collection. For 100 years itbeen a public tradition in mid-May

descend upon the Syringa on Lilacto enjoy and admire the diversi

of lilacs blooming upon the northeastof Bussey Hill While the majority

the some 200 taxa in the collectionornamental cultivars a number of

e 22 species are well represented byof known wild origin.

lacs have been part of the Arboretum sprogram for many years with

e collections used in the fields ofand pathology in particuTheArboretum s plant propagatork Alexander has also played a role ine development of ornamental selecns.Two notable recent introductionsSyringa x chinensis Lilac Sunday

d Syringa Purple Haze .

Of the nine known species of hemwe have within our collection

e seven that are hardy in our climate:canadensis, 1: carotiniana, 1: chinen-1: diversijotia, 1: heteropbylla,

and 1: sieboldii. The fITstspecies are particularly well repreby numerous wild-origin acces

and the collection of 1: canaden-contains nearly 50 ornamental

The significance of hemlockt heArboretum predates its founding1872 for one of the most prominentmordial landscape features is 170-ftHemlock Hill which is blanketed

a stand of 1: canadensis. Althoughof it was devastated during theamous hurricane of 1938 it gradually

to distinction through naturaland the intentional plant

of seedlings.However another threat followed:

e introduction of the hemlock woollyHWA,Adelges tsugae to orth

a from Asia in the 1950s. Firstovered at the Arboretum in 1997

the insect has since become a severepest threatening the survival of thenative stand of 1: canadensis as well asthe many accessioned 1: canadensis and carotiniana. TheArboretum s policyis to control HWA on those trees thatare accessible. However due to thesteep topography of Hemlock Hill notall trees can be treated. Interestinglyou t of this dim scenario has emerged anumber of research opportunities.ninvestigation into understory regeneration and biogeochemistry is currentlybeing carried out in collaboration withresearchers from the Harvard Forest. Inanother recent and related study resistance to HWA attack in other hemlockspecies in the collection was evaluated.With regard t o the latter project 1:chinensis, which was introduced fromChina byWilson has shown the greatestpromise and has been a driver inexpanding the genetic base of thisspecies in our collection.

onclusionEach of the six genera in our collection has its own unique history researchpotential ornamental appeal andmanagement regimes. As individualseach stands out is granted notice andapplauded as soloists.Yet as an ensembleour NAPCC collections are consideredexemplary and representative of ourcomprehensive living collection.Withour institutional commitment is therecognition that none of these genericcollections can ever be deemed complete: there always will remain theneed for further development throughacquisition and enhancement throughdocumentation and research.

Michael osmann is Curator ofLivingCollections, Peter Del Tredici isSenior Research Scientist, and Ericsu is a former Putnam Research ellowat the ArnoldArboretum ofHarvard University in JamaicaPlain, Massachusetts.

napcc article public garden 222 2007

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