at the Arboretum . ( See the full list by searching for “ Quercus ” in the online Collections Database at depts . washington . edu / uwbg / gardens / bgbase . php .) Two historical factors are responsible .
First , when the Massachusetts-based Olmsted Brothers firm was laying out Seattle ’ s park system early in the 20th century , it emphasized big street trees from back East . Many of the oldest oak specimens are strung along the south end of Lake Washington Boulevard by the Japanese Garden . ( The Boulevard was developed a few decades before the establishment of the Arboretum in 1934 .) Another early-planted grouping is out on Foster Island . Original data for these accessions are quite thin , and one occasional pleasure for Ray has been trying to figure out the identity of specimens in relation to the Olmsted plans . Just a couple of individuals remain unidentified .
If you look at the historic records for these plants , you ’ ll see many of them don ’ t have complete accession number dates . ( They are instead designated with an “ X ,” indicating uncertainty .) Also , some “ predate WPA ,” short for the Washington Park Arboretum . Of the oaks marked with an “ X ,” most are trees of eastern U . S . origin . In addition to the three species mentioned above , there are a good number of white oak ( Q . alba ), bur oak ( Q . macrocarpa ), and chestnut oak ( Q . prinus , now named Q . montana ). Another abundant “ pre-WPA ” tree along the Boulevard is the common oak ( Q . robur ), a European species popular in parks and public gardens worldwide . It has proved weedy in King County , however . ( In my little corner of “ old ” Mercer Island , common oak and its hybrid derivatives are by far the most common selfsowing oaks .)
The second reason for the predominance of eastern oaks can be traced to early partnerships with other arboreta . When the idea of
a collection arboretum was implemented in 1936 – 38 , a call for seed contributions went out in substantial measure to large , institutional sources east of the Rockies , such as Harvard ’ s Arnold Arboretum and the Morris Arboretum in Philadelphia . Washington Park Arboretum ’ s founders laid out a taxonomic arrangement for the new collections , and the oaks were sited in the northern section of the park ( just west of the current Graham Visitors Center ) in accordance with the Olmsted Brothers ’ Master Plan of 1936 .
The accession numbers from the late 1930s tell how the range of species from the East Coast , Southeast and Mississippi Valley filled out the main collection site . Among them are swamp white oak ( Q . bicolor , with its notably white leaf undersides and native range of Maine to Kansas ); turkey-foot oak ( Q . falcata , native from New York , sweeping southwest to Texas ); shingle oak ( Q . imbricaria , mainly from the central Ohio and Mississippi valleys ); chinkapin oak ( Q . muehlenbergii , the most widespread North American species , ranging from New England to New Mexico ); and many specimens of water oak ( Q . nigra , a bottomland species from New Jersey south and west to Texas ).
Putting these species together , you might think you were visiting the humid forests of Kentucky , Tennessee or southeast Missouri , where just about all of them converge . However , accessions from this period also included lots of daimyo oak ( Q . dentata )— profiled in the Fall 2019 issue of the “ Bulletin ”— and a few other selections from East Asia , again emphasizing origins with humid summers !
How have the big trees from continental climates fared here ? The big oaks from ENA have grown big — and are still growing ! From Ray ’ s perspective , the original choice to plant , say , five specimens of each taxon rather than maybe two has had some negative consequences . The oak canopy , together with
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