The Campaign for the Living Collections is an ambitious, 10-year initiative of plant exploration, propagation, and collections development—a major effort to increase and diversify the living collection of the Arnold Arboretum. For the duration of the Campaign, the Arboretum is mounting four to five collecting expeditions each fall, both in temperate habitats in North America as well as those in other parts of the world. ARBlog features firsthand stories from the field by our intrepid staff explorers.
We begin our journey in the northern edge of one of the most botanically biodiverse regions of North America. Here the wide range of climate and elevation hosts many unique species we are targeting on this expedition. In fact, more collections were made here than any other site we will visit. Of our many collections, we are most pleased to bring back Pinus lambertiana (sugar pine), the largest pine in the world. These trees can reach heights of 260 feet in height with trunk diameter of 11 feet at breast height. Their cones, which typically dehisce in the spring, tempered our expectations for harvesting this grand species. However, after miles of driving on harrowing logging roads and stopping to canvas numerous groves, we happened upon one individual with foot-long cones just out of reach with pole pruners. Fear not! After a few tries with our rusty throwline and weight, we were able to acquire five ripening cones—success!
Junipered hillsides and ranched valleys give way to the dry slopes of the Ochoco National Forest near Prineville, Oregon. Here, we targeted one of the most heat-tolerant populations of Larix occidentalis (western larch) and made three collections. We thank our collaborators, Preston Pew and Sean Hogan of Cistus Design Nursery in Portland, Oregon, for tipping us off to this remarkable collecting location.
From Little Crater Lake to the Clackamas River
Mount Hood and its watersheds are part of the Cascade Range, home to an abundance of species on our target list. Near the Pacific Crest Trail and Little Crater Lake we made collections of Cornus unalaschkensis (bunchberry) and Taxus brevifolia (Pacific yew). We were thrilled to find ripe arils (cones) of the latter taxon, since previous attempts in the Northwest yielded no viable seeds. Collecting Taxus brevifolia is challenging because this understory species is frequently removed to allow access for loggers. It was also heavily harvested for its life-saving compound, taxol, which is effective at treating breast cancer. With advances in chemistry, chemists are able to create a synthetic version, which has decreased collecting pressures on the species.
Our collecting site along the Clackamas River yielded the most target taxa of any area on this expedition. These species include: Acer circinatum (vine maple), Acer glabrum (Rocky Mountain maple), Philadelphus lewisii (mock orange), Tsuga heterophylla (western hemlock), and Viburnum ellipticum (oval-leaved viburnum). We are also pleased to bring a new species to the Arboretum: Gaultheria shallon (salal or shallon).
On to Leavenworth, Washington
With eager anticipation we head north to the alpine meadows of Cascade Mountains in Leavenworth, Washington. This small town is known for its Germanic charm, but we are headed there to collect Larix lyallii (alpine larch) and Pinus albicaulis (whitebark pine), which can only be found above 6,000 feet in elevation. Our approach to these rocky slopes will require a stiff hike with an elevation raise of approximately 1000 feet per mile along Fourth of July Trail.