This is a blog about the native conifers of the Pacific Northwest. It is a companion to the Northwest Conifers site. The blog will focus on timely and interesting details about our conifers, their connections to the rest of the environment, and our connection to them.

Saturday, February 9, 2019

The White Pines

The Pinus genus has more species than any other genus of conifers, by one count 114, and by any calculation, too many to keep track of. So it’s no surprise that taxonomists have divided the pines into two subgenera. One group, subgenus Pinus, is typically called the hard pines. Natives of the Pacific Northwest in this group include lodgepole pine, ponderosa pine, and Jeffrey pine. The other group, subgenus Strobus, is called the soft pines or white pines. The white pines of the Northwest include western white pine, whitebark pine, sugar pine, and limber pine. Since all of the white pines have needles that grow in bundles of five, they are also called five-needle pines. This is a good thing to remember, because it is how you can distinguish them from the other native pines, which have two or three needles per bundle.

Western white pine
What is the difference between hard pines and soft pines? These descriptions refer to the wood. We usually think of hard woods as the wood from flowering trees, for example, oaks and maples. However, some conifers produce relatively harder woods than others. Fir and hemlock wood is fairly soft. The wood of white pine is moderately soft. White pine has been used for construction, although much of the white pine forests of North America have been cut down. Eastern white pine was once the preferred tree for the masts of sailing ships in the British Navy. In fact, the British went around marking suitable white pines for the exclusive use of the King. Unmarked white pines were put to other uses, including house construction. The light color and moderate softness of white pine make it a good choice for window frames and other finish lumber. It is easy to carve, mill or sand, and retains its shape. Whether painted or stained, it finishes well.

Western white pine (Pinus monticola) is the most common native white pine of the Pacific Northwest. It can grow to over 200 feet tall and has cones that are larger than eastern white pine (Pinus strobus). Both trees have cones with a characteristic banana shape, but those of western white pine are also about the size of a banana. However, the sugar pine (Pinus lambertiana) is the granddaddy of the white pines. In fact, it is the tallest of all the pines. The tallest sugar pine is in Yosemite National Park and is over 270 feet tall. Just as notable, the sugar pine has the longest cones of all the conifers, up to 19 inches long. 

Sugar pine

If you frequent the higher elevations of the Cascades, you will meet another, very different white pine. The whitebark pine (Pinus albicaulis) that grows here is not large in stature, but these pines are a very important food source for some very important birds, if the amount of noise the birds make is any measure of their importance. These birds are the Clark’s nutcracker and the Steller’s Jay. The cones of other native white pines open and distribute their winged seeds when they mature. Not so with whitebark pine. These cones remain closed on the tree until a nutcracker or jay comes along to pry the cone open and extract the seeds. They eat the seeds or hide them to eat later. The relationship between whitebark pine and the Clark’s nutcracker is such a close one that whenever you hear a Clark’s nutcracker, you can be sure that whitebark pine is nearby. This relationship between the two is a symbiotic one. The nutcrackers get some food. The pines benefit by getting the birds to distribute their seeds to places where they can germinate. No doubt, this is not the intention of the birds, but they don’t remember where they “planted” all those seeds, despite the fact that researchers extol their memory capabilities. Not even a genius can remember everything. That is why whitebark pine has spread all over the cascades. Either that or the nutcrackers just hide more whitebark pine seeds than they can eat.  

Whitebark pine

Similar species of white pines grow all over the Northern Hemisphere. Mexican white pine (Pinus ayacahuite) is closely related to eastern white pine. Other species, called the stone pines, have large edible seeds like the whitebark pine, including Italian stone pine (Pinus pinea) and Swiss stone pine (Pinus cembra). Those expensive pine nuts you see in the grocery store may have come from these European species, but more likely they are Korean pine (Pinus koraiensis).

White pine blister rust is a disease caused by an Asian fungus species, which was introduced to North America over 100 years ago. It has caused serious damage to the white pines all across the U. S. In the Northwest, white pine blister rust has infected large areas of whitebark pine. Efforts are now underway to develop genetic strains that are resistant to the disease. More information.