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A New Curator for the Future of the Arboretum’s Trees

When you enjoy the blooms of the Magnolia Collection in early spring or stroll through the Maple Collection amid the colors of fall, you are experiencing The Morton Arboretum as a museum of living trees. As in any museum, its specimens must be collected, selected, recorded, labeled, and cared for.

Kim Shearer, as the Arboretum’s new curator of collections and manager of new plant development, manages the staff who do all that.

Her biggest job as curator, she says, is to set priorities. “No arboretum can include every kind of tree,” she says; even in 1,700 acres, there are limitations of space, climate, and soil. She must match the Arboretum’s horticultural, scientific, and conservation purposes to the trees that grow on its grounds.

Trees and other plants—mostly species that have evolved in the wild, but some deliberately selected cultivated varieties—are chosen based on a variety of criteria. Some will make a collection more complete, showing more of the full range of oak or maple or linden species or a greater variety of plants from a particular area of the world. Others may be given refuge at the Arboretum because they are especially rare or they are threatened in their native habitats. Today, the living collections include more than 100,000 living trees and plants belonging to more than 4,000 species and cultivated varieties.

Shearer came to the Arboretum in 2016 as its tree and shrub breeder and became the manager of the Daniel P. Haerther Charitable Trust New Plant Development Program. She is chair of the Woody Plant Crop Germplasm Committee, a group of experts who advise the USDA on needs for the development of trees and shrubs. “I had already curated a collection of plants for development purposes,” Shearer says. “Now, as curator of the entire living collection, I can broaden my focus.”

Her view now takes in the collections’ overall purpose to gather and preserve living plants that are valuable for horticulture, scientific study, and conservation efforts. One way to think of these trees, she says, is as a bank of genetic possibilities, somewhat like a seed vault. It’s especially important to grow living specimens of some species such as oaks, whose seeds can’t be saved because they don’t keep.

The genetic diversity stored in the collections has many uses. It can help researchers understand how trees’ genes affect their growth or how species from a variety of places around the world respond to changes in climate, or this diversity can be used to develop new kinds of plants.

The considerations that go into selecting the collections’ trees have changed over the Arboretum’s more than 100 years. Today, for example, one of Shearer’s urgent goals is to work with other Arboretum experts to develop a climate change plan for the collections. How will an increasingly variable climate, with more storms, drought, and flooding, affect the Arboretum’s trees? What kinds of trees should be added to the collections over the next few decades, given that tomorrow’s climate will be different from yesterday’s and even today’s? What facilities, staff, procedures, and policies will help their long-term survival?

A major project already underway is the transformation of the China, Japan, and Korea collections—some of the Arboretum’s oldest, dating back to the 1920s—into a single, broad collection of trees from temperate parts of Asia. This makes more biological sense—“geopolitical boundaries don’t mean anything to plants,” she says—and it also provides a remodeling opportunity. Some species that are not well suited to low-lying, wet sites along the DuPage River are moving uphill, where they will be safe from flooding. The new collection is also being re-imagined to better welcome visitors, with new site design and interpretation supported by a grant from the Institute of Museum and Library Services.

One priority for Shearer and her team is learning more about the soil in various parts of the Arboretum. “You can’t have healthy trees if you don’t have healthy soil,” she says.

Shearer continues to oversee the breeding and selection of new plant cultivars, and recently hired a new tree and shrub breeder and plant genomics specialist, Nathan Maren, PhD. The Arboretum has been introducing cultivated varieties of trees and shrubs since the 1960s, but the work has taken on increased importance as a changing climate demands more resilience from trees in city and suburban sites. Shearer also plans to expand efforts to evaluate existing plant cultivars and develop current recommendations for gardeners and the landscape industry.

How do you become a plant curator? It starts with an interest in and love of plants. Shearer grew up as an “Army brat,” yet “plants were a constant,” she says. She remembers visiting parks and forests from Massachusetts to Korea to Germany. Her mother made gardens everywhere. Eventually, Shearer settled down long enough to study horticulture in North Carolina and Oregon before coming to the Arboretum.

As a self-described nomad, she looks forward to restarting the plant-collecting expeditions stalled by the coronavirus pandemic. Collaborating with local researchers to collect plants from the wild and record details about their precise location and habitat, is important to science and has been a building block for the Arboretum’s collections since its earliest days. Shearer is starting with a scouting trip to Wisconsin this summer and has hopes for future forays to central Asia, Japan, and Korea, her mother’s native land.

Another goal is to develop internship programs and other opportunities for young people in the collections department and to find sources of funding. “There are so few opportunities today for young people to discover horticulture and plant science through hands-on experiences,” she says.

At a museum where the specimens routinely outlive the staff and experiments can run for decades, a collections plan developed in 2002 provides continuity from one curator to the next.  Still, every curator is different. “The role has always evolved, based on who is in the position,” she says. “What I do may not be what a curator will do in a hundred years.”

As the collections live on through the decades, the curators who care for them will continue to be true to the indenture that founded the Arboretum in 1922—calling for the creation of collections “for convenient study” in order to “increase the general knowledge and love of trees and shrubs, and bring about an increase in their growth and culture.”