As you wander through the rolling landscape of The Morton Arboretum, it’s a delight to stop in a grove of trees. They may be oaks, their spreading limbs stark but mighty against a winter landscape. They may be magnolias, flaunting grand, elegant flowers in April. Or possibly lindens, with their sweetly fragrant flowers in June.
These groups of trees may seem naturally beautiful, but they have been planned. Each is a collection purposefully assembled from around the world. Trees that would never grow together in nature—that may have evolved on opposite sides of the globe—are gathered here to serve science and, perhaps, to save their species.
In large part because of these collections, the Arboretum has been accredited by the American Alliance of Museums, the highest national recognition for a museum.
As in other museums that might accumulate fossils or ancient bits of pottery, the Arboretum’s collections are intended not just for display but to be preserved and studied. The difference is that here the treasures are alive, and they need care to live for many decades.
The Arboretum has been gathering trees since its beginnings in the 1920s. Founder Joy Morton collected plants on his travels or obtained seeds and cuttings from other botanic gardens and from adventurous collectors.
Adventurers still are bringing back trees today: Kunso Kim, head of collections and curator, and Kris Bachtell, vice president of collections, have brought back endangered magnolias, ashes, and other plants from China, Korea and other regions. Partnerships with other public gardens are another source of trees.
The most essential goal is to preserve species from around the world whose native habitats are being lost as development and other forces overcome forests. “The overall theme is conservation,” Kim says.
But having a wide array of similar tree species also allows scientists to investigate how they are related and how they evolved, or which species may be most able to adapt to climate change.
Breeders work with flowers, pollen, and seeds from a variety of species as they try to develop better trees. The Arboretum’s collections of elm species from Asia and Europe were crucial to developing hybrids that could resist Dutch elm disease. Now, with access to ash species from China, researchers are looking for species or possible hybrids that might resist the devastating emerald ash Borer.
Trees only are added to the collections if their origin and native habitat are carefully documented. Knowing where a tree came from is crucial to understanding both its evolution and its potential.
Some of the core collections of the Arboretum have special recognition from the North American Plant Collections Consortium (NAPCC), through which public gardens collaborate to conserve plants from around the world by giving them a safe place to live. The Arboretum’s collections of oaks, elms, maples, magnolias, and crabapples are recognized by the NAPCC, with lindens soon to join the list.
Lindens are a good example of why conserving species in the collections is so important, Kim says.
The millions of lindens planted in cities around the world belong to only a few species and hybrids. If a linden disease or pest should come along to mow them down, the Arboretum’s diverse collection of lindens might harbor a tree that could resist it.
As lovely and enjoyable as the Arboretum is for its human visitors, above all it is a safe home for its trees.