By Margaret O’Hartigan

Portland’s urban canopy of trees is shrinking – and a growing number of factors make it increasingly difficult for Portland’s ancient trees to survive

Monkey puzzle trees are “living fossils.” Believed to be the oldest ancient conifer still on earth, fossils almost identical to today’s trees are found in rock 160 million years old. Having survived one mass and two major extinction events, these trees take up to 40 years before bearing seeds. While the seeds are edible, the trees’ tough, spikey leaves can draw blood – and up close look like something fully capable of outlasting past contemporaries such as the dinosaurs.

Sadly, due to over-harvesting, the monkey puzzle is now considered an endangered species in its native Chile – which makes its presence in Portland all the more important. The species was first brought out of its native Chile by Archibald Menzies, the Scottish naturalist on the 1791-1795 voyage of the Discovery as Captain George Vancouver explored and explored the west coast of the Americas – including Oregon. The mature trees growing in Portland, however, are almost all about 115 years old, having arrived as seeds available to fair-goers attending the 1905 Lewis and Clark Centennial Exposition.

The huge Ponderosa pine at 29th and Northeast Fremont is yet another arboreal survivor. As early as 1885 this tree marked the northeast corner of Samuel Pearson’s 20-acre farm. Pearson salvaged the tree as a young seedling from an area burned over by wildfire – and like Portland’s other ancient trees, has since survived windstorms, ice storms and the Columbus Day storm of 1962.

The Pearson Ponderosa was designated a Heritage Tree in 2008. In 1993 Portland began recognizing trees due to age, size, type, historical association or horticultural value. Heritage trees must be protected during development.

There are dozens and dozens of designated heritage trees in north and northeast Portland, and a guide to all of them – by species and location – can be found by logging on to:

American chestnuts behind the North Portland library building at Killingsworth and Commerce are also survivors.

130 years ago this species was the most commonly planted tree in U.S. cities. Chestnut trees were grown for shade, wood and food. Chestnuts were an integral part of the American psyche, from poetry (Longfellow’s “Under a spreading chestnut tree, the village smithy stands”) to song (“Chestnuts roasting on an open fire”). But the vast majority of living Americans have never seen one.

That’s because in the first decade of the 20th century a fungal disease struck American chestnuts. The devastation was so complete that in its original range the tree is functionally extinct. However, west of the Cascade and Sierra Nevada mountains a few lucky trees avoided the blight.

North Portland is especially fortunate, for in addition to the library tree, 4 blocks east of the library is a stand of three American chestnuts along the east side of Williams Avenue just south of Emerson Street.

Portland’s urban canopy of trees is shrinking – and a growing number of factors make it increasingly difficult for Portland’s ancient trees to survive. In addition to urban pollution, invasive diseases or pests and an ever-changing environment, the city government’s desire to increase density replaces single-homes sporting big enough yards to support large trees with lot-filling multi-family dwellings.  If you want to give endangered trees a better chance at survival, you can learn how to nominate a Portland tree for heritage status here.