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.

Thursday, July 28, 2022

Focus on Jeffrey Pine

You’re probably familiar with ponderosa pine. It is the iconic tree of the western U.S., easily recognized by its distinctive, puzzle-piece, orange bark. Its cones are also distinctive, egg shaped, 3 to 6 inches long, and notoriously armed with painful prickles. However, if you travel to southwest Oregon, you may find what looks like a ponderosa pine with cones that are twice the size of ponderosa cones. They may be as large as 10 inches long. Congratulations, you have just discovered a Jeffrey pine.

It's no surprise that Jeffrey pine is a relative of ponderosa pine. Except for the cone size they are often difficult to tell apart. The size isn’t the only difference in the cones. Both have sharp prickles on the scales, but the prickles on Jeffrey cones point inward when open, while Ponderosa prickles generally point outward, just waiting for an unsuspecting hiker to pick up the cone. This difference in prickle orientation has been noted by some as a telltale difference between the two with this mnemonic device: Prickly ponderosa, Gentle Jeffery. However, this is not a reliable distinction. The prickles on both trees are variable. But here’s a better distinction: 

The prickles on ponderosa are short and curved, while the prickles on Jeffery are longer and straight. Note that if you are impaled by a Jeffery prickle, you may find that your finger is trapped by the prickle and the scale below! It’s very painful and difficult to remove.

The cones open when ripe and drop the large, winged seeds. They aren’t likely to fly very far, but they are a favorite food of the Clark’s nutcracker, Steller’s jay, squirrels, and chipmunks. They will eat them or cache them for eating later. Not all cached seeds are needed or remembered, so seeds that are cached in the soil often become the next generation of Jeffrey pines.

Jeffrey pine grows throughout the Sierra Nevada Mountains of California. Like many conifer species that are native to California, the range of Jeffrey pine crosses the border to a few locations in southwest Oregon. For example, you can find them growing along Interstate 5 north of Grants Pass and along Highway 199 near Cave Junction.

Jeffrey pine often grows in nutrient-poor soils where other species cannot grow. Does this mean that it thrives in these conditions? Not so much, but it does better than competing species. Jeffrey pine is smaller than ponderosa pine, growing to 130 feet or more.

Jeffrey and Ponderosa Needles

Like ponderosa pine, Jeffrey pine has 3 needles per bundle. Ponderosa pine needles tend to be bunched at the ends of the branches. Jeffrey pine retains its needles longer than ponderosa pine, so they typically remain farther along the branch.

For example, note this curious branch on a ponderosa pine in my yard. It looks like it did well some years and the needles remain, while the needles are missing from other years.

Jeffrey pine bark

Jeffrey pine bark looks similar to ponderosa pine with flat plates shaped like the pieces of a jigsaw puzzle. But Jeffrey pine bark is brown rather than orange. However, the bark on ponderosa pine can also look very much like Jeffery pine bark, especially on ponderosas growing in the Willamette Valley.  The bark is variously described as smelling like vanilla, lemon, or pineapple. But ponderosa bark can smell like lemon, so smelling bark may not be a good way to identify them.

Ponderosa pine near Bend, OR --- Ponderosa pine near Portland

Jeffrey pine was named after Scottish botanist John Jeffrey, who discovered it in1852 growing in the Shasta Valley in California. Other common names: western yellow pine and bull pine.

The wood is similar to ponderosa pine, and both are marketed as ponderosa pine or yellow pine. Pine sap can be distilled to make turpentine, and ponderosa pine was used to make turpentine in the eighteenth century.* However, if you try to make turpentine from Jeffrey pine sap, the result is heptane, which is highly flammable and explosive.** Be forewarned. If you think you want to make your own turpentine, be sure you know how to identify these two species. The best way to identify Jeffrey pine is by the size of its larger cones. And the safest way to get your turpentine is from a paint store.

See also

NW Conifers

*The Gymnosperm Database

**OSHAreports 10 people injured or killed by explosions or fires since 1988.

Thursday, February 17, 2022

The Great Douglas Fir Migration

Thousands of years ago, people from Siberia migrated across the Bering Land Bridge, which connected Asia to North America. We don’t know if they were explorers looking for new land and opportunities, or if they were driven by famine or drought. They could have been escaping religious persecution like some of the Europeans who came to North America thousands of years later. In any case, it was an adventure, and the adventurers spread across all of North America and into South America.

Millions of years earlier, another migration crossed the Bering Land Bridge in the opposite direction. However, it wasn’t a migration of people. It was a migration of Douglas fir trees. The story of this migration starts in Mexico. The first Douglas fir originated in northern Mexico some 50 million years ago. Douglas fir is closely related to the larch, which evolved from the pines. Douglas fir either branched from the same pine ancestors or from the larch. In either case, the two took quite different forms, the larch becoming deciduous with bundles of needles, and Douglas fir growing evergreen needles that resemble those of the spruce and fir. 

Bigcone Douglas fir
After its departure from the larch, Douglas fir began a long journey north, with some of them branching off to southern California to enjoy a warmer climate. They became a separate species we now know as bigcone Douglas fir (scientific name: Pseudotsuga macrocarpa). As both the scientific name and the common name imply, they have larger cones than the Douglas fir of the Pacific Northwest, although the trees are much smaller. Meanwhile, the trees that continued their migration north became what we know as Douglas fir (Pseudotsuga menziesii). 

Now we must stop and face this question: How can trees migrate? Unlike the strange, magical trees that destroyed the Orcs in “Lord of the Rings,” trees in our world remain rooted in one spot their entire lives. Yes, but their winged seeds can travel! They are adapted to do just that. Let’s suppose that in 100 years a tree grows to be 100 feet tall and produces seeds that are blown a conservative 200 feet from the tree. Thus, the forest would move 200 feet in 100 years, or on average, 2 feet per year. At that rate, it would take about 2500 years for the trees to migrate one mile. It may seem impossible for this forest to migrate all the way to Oregon, until you consider that it had millions of years to complete the trip. At this rate of one mile every 2500 years, the offspring of these seemingly immovable trees could be growing in Portland in less than 3 million years. Not content to linger in Portland, they continued right up the Pacific Coast to Alaska and across the Bering Land Bridge and south into Asia

Before they migrated very far, they faced another difficulty that might have stopped them before they even made it to Portland. The problem is this: As they migrated farther north, the climate changed. With these changes in the climate, the trees must adapt to the new environment. Douglas fir adapted to many changing conditions in their journey north to Alaska and then south into Asia. The journey was not without its setbacks. For example, they encountered a changing climate and several ice ages. And they required the right conditions for their seeds to germinate and survive. Douglas fir seeds germinate best in a seed bed of bare soil. Finally, they may have been stopped by open ocean at the Bering Strait, but at least once the Bering Land Bridge formed and allowed them to cross into Asia. 

Douglas fir seeds with wings

As they moved south through eastern Asia, they adapted to the conditions in different locations, and developed into several new species, including one in Japan, one in Taiwan, and several in China:

  • Japanese Douglas fir (Pseudotsuga japonica), is limited to Japan. Like all of the Asian species of the genus, it is smaller than the Douglas fir of the Pacific Northwest, growing to 100 feet. The cones are also smaller, only 2 in. or less. This species grows only rarely on steep slopes up to 3600 feet elevation.
  • Formosan Douglas-fir, (Pseudotsuga wilsonia), grows mostly in Taiwan with a few locations in China. It is closely related to the Chinese species.
  • Several species of Douglas fir grow in China. Like the Japanese Douglas fir and Formosan Douglas fir, these species are smaller than those of North America and have smaller cones.

Many other conifers have taken similar migrations from North America to Asia across the Bering Land Bridge including some of the true firs (Abies genus), spruce, and pines. And remember the ancient relatives of the Douglas fir, the larch? I suspect the larches took a similar journey, not only migrating to Asia, but to Europe as well. Here in North America, it appears that while migrating north, they also made a right turn and migrated to the East Coast and all across Canada. Some remained in central Alaska.

More recently and closer to home, Douglas fir has been adapting to different conditions here in western North America. Most notably, they have migrated north and south as well as up slope and down slope, with changes to the climate. Cold weather and glacial ice forced them south many times in the past thousands of years. When it warmed and the ice melted, they were able to migrate north again. Note that the glacial till left by the retreating glaciers was the ideal seed bed for the germination of Douglas fir seeds. 

The Cascade Mountains have imposed an interesting split in the population of Douglas fir in the Pacific Northwest. As the saying goes in biology, “Absence makes the genes wander.”  Whenever the members of a species are separated by a barrier, they will develop genetic differences. And if the environment is different in the separate populations, we will be able to see these differences as they adapt to the different conditions. 

As everyone from Oregon and Washington knows, the climate west of the Cascades is mild and damp, well in truth, wet. On the other hand, east of the Cascades, it is dry and prone to temperature extremes and drought. As the separate populations of Douglas fir adapted to these different environments, they evolved into two distinct varieties, and we can now see the differences between them:

Coastal Douglas fir (Pseudotsuga menziesii var. menziesii) now grows in western Oregon and Washington from sea level up to 5000 feet. It also grows along the coast of British Columbia and in the coastal mountains and Sierras of California. This variety grows faster and taller but is less drought tolerant. The needles are green, and the bracts on the cones lie flat on the scales.

Rocky Mountain Douglas fir (Pseudotsuga menziesii var. glauca) grows between 2000 and 7000 feet from central Oregon to the northeast corners of Oregon and Washington, and up into Canada. It also grows throughout the Rocky Mountains up to elevations of 9700 feet, and up to 10,700 feet in Arizona and Mexico. The needles of this variety tend to be blue or gray compared to the coastal form. The bracts on the cones tend to protrude outward from the cones.

As the climate warms, we can expect Douglas fir to change as they try to adapt to new conditions. Or they may attempt to migrate to cooler locations, higher or northward. The problem they face is that the climate is changing quickly. Can the trees keep up? Trees do not adapt or move quickly. Some foresters and volunteers have tried to assist by planting seedlings in new locations where they can grow successfully. This may have some effect, but ultimately, we must stop doing the things that are causing climate change. Can we do that?


More  Info

Douglas-fir: The Genus Pseudotsuga, Denis P. Lavender and Richard K. Hermann. You can download the PDF here.

Intercontinental disjunctions between eastern Asia and western North America in vascular plants highlight the biogeographic importance of the Bering land bridge from late Cretaceous to Neogene by Jun Wen, Ze-Long Nie, and Stefanie M. Ickert-Bond. Journal of Systematics and Evolution 54:469–490.

See the following topics at The Gymnosperm Database by Chris Earl:


Pseudotsuga menziesii

Pseudotsuga  menziesii subsp. menziesii 

Pseudotsuga menziesii subsp. glauca

Thursday, December 16, 2021

Pernicious Personification

Four hobbits are riding their ponies on a shortcut through the Old Forest. But the Forest keeps hindering them, forcing them down, down into a valley where they rest by a river under a large willow tree. One hobbit, who is cooling his feet in the water, suddenly finds all of himself in the water. When another hobbit pulls him out, he says, “… the beastly tree threw me in! I felt it. The big root just twisted round and tipped me in.” The personification of trees is a theme that runs throughout The Lord of the Rings. Generally, personification runs through old myths, fables, and literature, especially fantasy. Anthropomorphism, attributing human intentions and characteristics to objects, is something we all do. I can’t tell you how many times a tree has stuck a root up and tripped me while hiking. We all understand that these attributions are not literal. 

This kind of anthropomorphism also appears in nature writing. Some of this is innocent enough. It often adds some whimsy to the narrative and stimulates the imagination. Valerie Trouet does this in Tree Story, an engaging book on tree rings and what we can learn from them about climate, human history, and so much more. She talks about trees making wide rings when they are happy, but it’s clear that she doesn’t mean this literally. 

On the other hand, some nature writers do take their anthropomorphism literally. This is when anthropomorphism runs amok. For example, a recent book has become a controversial example of this kind of writing. It is The Hidden Life of Trees: What They Feel, How They Communicate by Peter Wohlleben. Just the title is enough to tell you where we are headed in this book. Inside, he talks about trees sending messages to their neighbors, tasting the saliva of insects, and screaming when they are thirsty. He defends these anthropomorphisms by saying that he wants to get his readers to value trees and treat them appropriately as beings with emotional lives. Surely we can see the value of trees just for what they are. And we will value them even more when we understand more about them, how they evolved, how they fit in an ecological system, and how they actually function in that system. We can see them as things of wonder and beauty without imposing human emotions onto them. 

Suzanne Simard describes her study of the forests of British Columbia in her book, Finding the Mother Tree: Discovering the Wisdom of the Forest. She tells of her studies of the complex relationship between trees and other life in the forest, especially the symbiotic relationship between tree roots and a network of mycorrhizal fungi. The fungi connect to the tree roots and branch out to collect nutrients for the trees. In return the trees send sugars to the fungi. This fungal network can connect to multiple trees and enable the transfer of nutrients from one tree to another. Simard has conducted important experiments on these relationships, especially on the transfer of nutrients from what she calls “Mother trees” to seedlings. She characterizes the Mother trees as talking to other trees. When experiments show that seedlings from the Mother tree thrive better than other nearby, unrelated seedlings, she characterizes this as Mother trees nurturing their young and says that Mother trees ‘recognize’ their own young. 

The research is groundbreaking and fascinating. But here I want to focus on the personification. Does it further our understanding? I argue that it does not. On the contrary, it distracts from our understanding. That is why I call it pernicious. When I read about research like this, I want to know why it is that the close relatives thrive more than the distant ones. What is the mechanism that allows them to do so? I suspect that it may be related to how the trees and the fungi evolved together. But when I’m told that the Mother tree recognizes her young, that tells me nothing about what the process might be. I can’t even make sense of that. But you say, “what about the evidence?” Let’s be clear: The evidence does not support the conclusion: It does not follow from that fact that the closely related seedlings thrive that the Mother tree recognizes them. This explanation is very simply not an explanation at all. 

Sometimes a metaphor can suggest a hypothesis that might lead to further investigation, but not in this case. Saying that the Mother tree recognizes her young misdirects us from any investigation of a possible relationship. Rather, we are directed to focus on the supposed intentions of the Mother tree and away from any investigation of the interactions between the roots and the fungal network.

I suspect that there is something in the genetic makeup of the tree and the fungi that might favor genetically similar seedlings. That is something we would want to investigate and would explain why the genetically distant seedlings might not  thrive as well. However, when we don’t understand the behavior of trees, we may be inclined to think of some analogous human action and ascribe intention and intelligence to it. But our lack of knowledge of the process is not evidence for the claim that trees are intelligent or have intentions. Again, rather than explain, this Anthropomorphism misdirects us from our search for an explanation. 

There are several lessons we can learn here:

First, beware of personifications given as explanations. They generally don’t explain.

Try to read personifications as innocent figures of speech. Sometimes they are.

Ask yourself: Does the personification lead you to consider an explanation? If not…

Be curious. Dig deeper, look for further explanations, or try to think of other possible explanations.

Oh, one more lesson: If you ever see a large willow tree by a river, do not sit under the tree and dangle your feet in the water!


See also

Pitfalls of Anthropomorphism: The Hidden Life of Trees

Facts or Fairy Tales? Peter Wohlleben and the Hidden Life of Trees

How Trees Talk to Each Other, Suzanne Simard - TED Tallk video

Do Trees Talk to Each Other?

The Intelligent Plant - The New Yorker