Renewal in the Linear Arboretum

We may not notice the trees all around us slowly growing older but they do. Eventually, like all living beings, they too reach the end of their lifespan. This is happening all along the Ainsworth median as the Norway maple monoculture gradually declines. Each year a few trees are lost to age and storms.

Friends of the Linear Arboretum are committed to ensuring that new trees are planted where old ones die. Instead of a “maple desert” - a same-age cohort of a single species - the new plantings are deliberately chosen to be from diverse families, genera and species. This is an insurance policy against catastrophic loss from a disease or pest that might attack a particular tree, such as the bronze birch borer now devastating birches in Oregon.

The latest additions to the median are a Kentucky coffeetree at NE 35th Place and a Japanese zelkova at NE 26th. While there are already a small number of zelkovas and two coffeetrees further west in the Arboretum, these are new cultivars that represent genetic diversity within their species.

True North was selected in Minnesota for its hardiness, superior branch structure and absence of seedpods. This is one of the first plantings of this cultivar in Portland - almost all recent coffeetree plantings have been of the Espresso cultivar. Likewise, while Green Vase zelkova has become much more common in Portland in the past 20 years, the Arboretum will be planting a different cultivar - Burgundy Vase. It is reputed to be more resistant to canker diseases.. Its fall color is also said to be more burgundy than the orange-red Green Vase. Visit in the fall to judge for yourself!

UPDATE! The new trees are in the ground as of March 22nd! Just in time for the April 16th walk, and for Ainsworth neighbor Ms. Georgia to enjoy the spring growth of the Kentucky coffeetree.

Tree Team member Ric Vetter and his three pups, Pele, Lani, and Maka, go on a walk to welcome the new trees. They are pictured here with the new Zelkova on 27th and Ainsworth.

One of the new trees in spring 2022 in the Linear Arboretum will be a newer variety of Kentucky coffeetree called True North (Gymnocladus dioicus ‘UMNSynergy’).