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.

Saturday, November 24, 2018

The Larch

Western Larch by Highway 35
We usually think of conifers as evergreen trees, and most conifers are evergreen. However, some conifer species are notable exceptions. They are deciduous. That is, they drop their needles in the fall and grow a new crop each spring. Most of these deciduous conifers are larches. Ten species of larch grow in the Northern Hemisphere, three are native to North America, and two grow in the Pacific Northwest. Western Larch (scientific name, Larix occidentalis) is the most common larch in the Northwest and the only larch native to Oregon. You may not notice the larches on your summer hikes in the Cascade Mountains, but in November, when the needles turn golden-yellow, they stand out like trees on fire. You can see them along Oregon Highway 35 north of Mount Hood Meadows.

Now, you may wonder, why do larches drop their needles in the fall? Other conifers growing nearby seem to survive the winter cold just fine with their needles intact. These conifers have adapted to the cold by moving water out of the cells in the needles, leaving a concentrate that acts like antifreeze, or by purifying the water in the cells so ice crystals can’t form even at temperatures well below freezing. The larches have adapted a completely different strategy. They just drop their needles in the fall and grow new ones in the spring. This enables larches to survive some of the coldest temperatures of any of the conifers, growing high in the mountains and in the northern latitudes of North America and Siberia.

Western larch
It takes a lot of energy to grow new needles every year. However, since the needles only have to last one season, they don’t need to be strong and durable. So less energy is needed to grow them. As a result, you will notice that larch needles are much more delicate than those of evergreen conifers. The same is true of the leaves on trees. Note how the evergreen leaves are thick and stiff compared to the delicate leaves on deciduous trees.

Western larch needles
Larches are easy to identify. The needles grow in bundles like a pine with about 25 needles in each bundle. In the Cascades, Western Larch grows mostly on the east side of the Cascade summit at elevations up to 6000 feet. It also grows in the mountains of northeastern Oregon and Washington, and in northern Idaho and western Montana.

Alpine larch (Larix lyallii) grows at elevations higher than Western Larch, near the timberline in the North Cascades in Washington. It also grows in the Rocky Mountains of Idaho, Montana, and Canada. 

Western larch is an important timber tree. The wood is nearly as strong as Douglas fir and is used for framing and finishing. Western larch is also a popular firewood in the Northwest. It is often called “tamarack” by wood cutters, a common name for the other North American larch (Larix laricna), which grows in the northeast United States, across Canada, and in central Alaska.

Japanese larch at Hoyt Arboretum
November is the time of the year to look for larches, when they display their fall colors. To see the larches at Hoyt Arboretum in Portland, start at the Visitor Center and walk west on the Fir Trail.

See Also
Fall Conifer Colors
How Do Conifers Survive the Cold?
Western Larch at Northwest Conifers

Sunday, November 4, 2018

The Elusive Fir Cone Mystery

Douglas fir cone
Did you ever wonder why you don’t find fir cones on the ground? Well, cones typically cover the ground under Douglas fir trees. But Douglas firs are not in the Abies genus, the genus of the true firs. Like many conifers, Douglas fir cones open in late summer or fall and commit their small, winged seeds to the wind. The seeds descend like little helicopters, where most of them become tasty morsels for chipmunks, juncos and other small birds. Some time later, the cones drop from the trees to the ground. This is why the ground under mature Douglas firs is usually littered with cones. 

Cone near the top of a noble fir

Unlike the Douglas fir, you will rarely see a cone under a noble fir. In fact, if you see any cones under a noble fir, they are likely cones from a nearby Douglas fir. If you look carefully at the top of a noble fir, you may see cones up there. But the cones don’t stay there forever. So what happens to all the noble fir cones?

Noble fir scale and long bract
Noble firs, like all the true firs, engage in extreme seed distribution. The cones don’t just open and distribute the seeds. They completely fall apart and let everything fall to the ground, seeds, scales and bracts, leaving only a narrow spike of the cone core on the tree. The winged seeds generally separate themselves from the scales and sail off in the wind. The scales usually fall closer to the tree. Although you won’t find intact cones on the ground, in late summer and fall, the ground under a noble fir is often covered with these cone scales, with the bracts still attached.

Grand fir scale with broad bract

When you see these cone scales on the ground, you can use them to identify the species of fir. Recently hiking the University Falls Loop Hike in the Coast Range, I noticed some scales had fallen onto the trail. Attached to the scales were long bracts that extended beyond the edge of the scales. These long bracts are unique to noble fir among the native firs of Oregon. All of the other native firs have much shorter bracts, which never extend beyond the edge of the scales. 

Pacific silver fir scale with tapered bract

Later on the University Falls Loop, there were some scales along the trail with bracts that were much shorter than the scales. These fell from a grand fir. Note the shape of the tip of the bract. Each species has its unique shape. Grand fir has a broad end with a narrow tip. If you hike above 5000 feet in the Cascades, you're likely to see Pacific silver fir and subalpine fir. Pacific silver fir bracts are tapered at the end and come to a point. Subalpine fir bracts are rounded with a small point at the end.

Subalpine fir scale with rounded bract

So, if you are out hiking in the fall, just look down. You may see the cone scales all over the forest floor. Then you will know what happened to the fir cones. Not only that, but you will be able to identify each of the firs by the distinctive bracts of each species. 

Occasionally, you will find a fir cone, or even several fir cones on the ground. If you do, you should step away from the tree. It’s likely that a Douglas squirrel is cutting them loose and letting them fall to the ground. Douglas squirrels have no time for chasing after loose seeds. They will cut a cone loose and then strip the scales and eat the seeds, or store the cone in a cache to eat later. A favorite of the Douglas squirrel is the seeds of the Douglas fir. They can strip the scales from a cone and eat the seeds in about five minutes, leaving only what I call a “cone cob.” If you see Douglas fir scales on the ground, you can be sure Douglas squirrels have been busy at that location. You can often see piles of these scales and the left-over cone cobs below the squirrel’s favorite spot for eating lunch.

Douglas fir scales and cone cobs