Pinus ponderosa var: willamettensis

Stephen Meyers, Dept. of Botany and Plant Pathology, OSU

Stephen Meyers, Dept of Botany and Plant Pathology, OSU sent an update on var. willamettenis status. The complete description of distinctive characteristics that warrant a specific variety for Willamette Valley Ponderosa pine is complete. The report will be submitted for peer review and publication in a botanical journal in 2010.


When most residents of the Willamette Valley of Oregon think of locally native tree species they are likely to mention names such as Douglas-fir or white oak. Many residents are unaware that ponderosa pine was once found in abundance throughout the Valley. Early European botanical explorers, such David Douglas in the early 1800ís, commented in his writings on the abundance of pines throughout the region. To this day, ancestors of those same native ponderosa pines, Douglas saw nearly 200 years ago, still exist, albeit in mainly small stands, within the Valley.

Unlike the ponderosa pine commonly seen east of the Cascades Mountains, Willamette Valley ponderosa pine is ecologically, and presumably genetically, suited for the high rain fall conditions of the Willamette Valley. However, despite obvious ecological differences, botanists have not officially recognized Willamette Valley ponderosa pine as a distinct taxon. Rather, Willamette Valley ponderosa pine is currently lumped within varieties of ponderosa pine that include populations of trees found east of the Cascade Mountains and/or within the Siskiyou and Sierra Nevada Mountains.

In order to describe and officially recognize a plant taxon, one or more reliable morphological characters must be found that distinguish the new taxon from others. In order to distinguish Willamette Valley ponderosa pine from the other named varieties of ponderosa pine, I have surveyed nine morphological characters, including needle and cone characters. These characters were measured and recorded from 50 populations of ponderosa pine throughout the Willamette Valley.

The data collected has revealed that needle width is a reliable and consistent character to distinguish Willamette Valley ponderosa pine. While the needles of other varieties of ponderosa pine generally are over 1.2 mm wide, the needles of Willamette Valley ponderosa pine are consistently less than 1.2 mm wide. This characteristic, in addition to ecological considerations, is sufficient to describe and recognize Willamette Valley ponderosa pine as a distinct taxon. The name I have chosen for this taxon is Pinus ponderosa variety willamettensis. A complete description of Pinus ponderosa var. willamettensis has been written and will shortly be submitted to a peer reviewed botanical journal. Publication of the description is expected in middle to late 2009.


Last Updated 02/28/10