When we think of museums, we often think of art, natural history and artifacts. At the heart of a museum’s identity lies a duty to collect, conserve, research, exhibit and act as a platform to engage and educate the public. How does an arboretum fit into this description?
Simply put, an arboretum is a living museum of trees. Like a traditional museum, the Arboretum’s horticulture, collections and research staff work to acquire and care for the living trees. Education staff invite visitors to explore the plants, trees and collections to learn about horticulture, botany, taxonomy, climate change and more. At the University of Minnesota Landscape Arboretum, the Pine Collection is a jewel in our living museum, conserving pines from around the world, while inviting visitors to explore the natural world among their evergreen branches.
The Pine Collection is one of two Nationally Accredited Plant Collections™ at the Arboretum recognized by the American Public Gardens Association’s Plant Collections Network. The collection, which was accredited in 2012, boasts 20 unique species that represent nativity from North America, Asia, Europe and Africa. Within this collection, visitors can find more than 250 specimens on display.
The current Pine Collection is located off of Three-Mile Drive and Walk, but before the Snyder Building was constructed in 1974, the Pine Collection used to stretch from the Herb Gardens through the Dwarf Conifer Collection. Keen-eyed visitors can even find some remnants of this collection in the Scots, Jack and Macedonian pines located due south of the current Herb Gardens. The Arboretum’s records indicate that the first pines added to the current collection were planted in the early 1960s, with roughly 60% of the living collections planted in the 1960s and 1970s, meaning they are around 50 to 65 years old.
Why pines?
Minnesota is known for its long winters, typically lasting around five months. Pines, which are conifers, are known for their evergreen foliage, or needles. Along with many other conifers, pines help add year-round interest to the landscape. The various forms, heights, bark color and needle color add visual contrast to an often “barren” landscape in the height of winter. Plant breeding and selection have led to an even more diverse selection of cultivated pines, which can also be found within the collection.
Minnesota certainly isn’t a global hotspot for pine species richness. While North America contains the highest diversity of pine species, much of that diversity is concentrated in Mexico. Recent studies have found that numerous ecological variables drive global distribution and pine species diversity; however, warm and somewhat dry habitats appear to be where they thrive and evolve at higher rates. Despite their ecological preferences, to this date, the Arboretum has been successful in growing roughly 17% of the global species diversity of the genus Pinus. This conservation of diversity allows the institution to act as a repository or germplasm bank for cold-climate-adapted pine species.
The various forms, heights, bark color and needle color of pines add year-round visual interest to the landscape and are especially valuable in the winter months when other trees have shed their leaves. Photo by Sara Pace
Future of the Pine Collection
Considering how important tree preservation is for an arboretum and the strong impact that climatic conditions have on tree health, the current and future climate outlook are at the forefront of decision making when it comes to selecting and caring for the specimens in the Pine Collection. In the relatively short period of time since the Arboretum was established in 1958, the climate has already shifted. Today, the Arboretum experiences overall warmer temperatures, in addition to more erratic and severe weather events, such as prolonged droughts, strong wind storms and hail events, as well as more intense periods of precipitation. This trend is predicted to continue to intensify into the future, and these challenges inform decisions about what types of trees we grow as well as the care they require.
Matching the right plant to the right place is a key theme among best practices in landscape horticulture. As a leading authority in landscape horticulture with a historic goal of showcasing the best plants for landscape use in the Upper Midwest, the Arboretum’s curators and horticulturists incorporate plants suited to our region’s conditions into the living collections. In some cases, the Curatorial Team is testing the limits of plant performance, while in others, we are simply choosing plants that represent the best of the best for our region.
When it comes to conservation or the added challenges associated with a changing climate, the Pine Collection sometimes needs a little help. Many of the collection’s pines grow on the grounds without the need for additional care. Others may be susceptible to biotic stresses, such as Diplodia tip blight or pine sawflies, requiring occasional support. But all plants can be challenged by extreme weather events. In addition to the care provided by the Arboretum’s plant health specialists, our arborists will often work on our pines, either in response to storm damage or to help prevent major failures in the future by carefully pruning to encourage and maintain healthy growth.
As climatic conditions continue to shift, and the Arboretum works to maintain the pines we have, the Curatorial Team will continue to expand the Pine Collection with new specimens of old standbys and with new trial trees that widen the diversity of the collection. Come sun or snow, the Pine Collection will continue to shine as the jewel of the Arboretum’s collections for many years to come, providing not only a respite for visitors but a living exhibit to educate and inspire.
Visit the Pine Collection this winter to explore pines from around the globe among the pristine beauty of the Arboretum’s winter landscape. The Pine Collection can be reached from Three-Mile Drive and Walk and can be accessed from parking lots near the Dahlia Trial Garden and Ornamental Grass Collection.
Cover photo by Sara Pace
This story was originally published in Arboretum Magazine, a quarterly magazine for members of the University of Minnesota Landscape Arboretum.