The horticulture staff at the Washington Park Arboretum are constantly planting new trees. These new plantings increase species diversity within the collection, succeed dead or declining trees, contribute to future increased canopy coverage and much, much more. All of the trees mentioned in this article were planted over the last year and are located within the Pinetum on the west side of Lake Washington Boulevard.

1)   Pinus monophylla

Single-Leaf Pinyon (Piñon)

This pine is unique as it only has one needle per fascicle (small cluster of needles). Most pines have two, three, or five needles per fascicle. Knowing how many needles per fascicle different species of pine have can greatly improve your ability to identify them. Pinus monophylla stays relatively small (30’-60’ tall) and has scaley, furrowed bark. The acute-globose cones, which take two years to develop, provide wildlife and humans alike with tasty seeds. Native to southwestern North America, especially in Utah, Colorado, Arizona, and New Mexico. This species is difficult to propagate and usually only does so with the help of specific animals such as the pinyon jay. Because of this, Pinus monophylla is rarely seen in nurseries. We were lucky enough to add two of these amazing trees to our collection this year!

Shea Cope

2)   Cupressus gigantea

Tibetan Cypress

A very stately, columnar-conical cypress with purple-brown bark and densely arranged branchlets. This tree eventually matures at heights between 60’-120’ tall and has a disproportionately large trunk compared to other trees of similar height. The largest known specimen of Cupressus gigantea resides within the Baji Giant Cypress Nature Reserve in Nyingchi, Tibet. It is widely celebrated as the spiritual centerpiece of the nature reserve and is aptly named King Cypress. This particular tree stands at roughly 180’ tall with a trunk diameter of 20’ and is estimated to be 2500 years old! We have 4 other Cupressus gigantea located within the Arboretum (all in the Pinetum). Two were planted in 1999 and the other two in 1948. They have quite the journey ahead of them if they wish to compete with King Cypress!

Shea Cope

3)   Picea chihuahuana 

Chihuahua Spruce

Based on its name, you might be surprised to find out that this tree can grow well over 80’ tall! It’s native to the Sierra Madre Occidental mountains in Chihuahua and Durango within northwest Mexico. It was discovered in 1942, is endangered, and only has 25 small populations within its native range. Picea chihuahuana is increasingly being planted as an ornamental specimen in botanic gardens. This is not surprising due to its attractive, widely spaced, drooping branchlets adorned by bright blue-green foliage. This tree also happens to be a contender for one of the most heat-tolerant of all spruces.

Shea Cope