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, May 30, 2019

Conifers in Spring

Douglas fir
What are conifers doing in spring?  Why is it that no one notices? Well, I suspect that it is because there is too much competition from more glamorous plants like tulips and trilliums. Not even the humming birds and bees seem to pay any attention to the conifers, not that we should blame them. The conifers don’t advertise and don’t offer any nectar. Apart from the stiff competition from flowering plants, why is it that we don’t notice the growth changes of conifers in spring? I think there are primarily two reasons. One reason is that most conifers are evergreen. When deciduous trees put out new leaves the change is transformative. You can’t help but notice the difference between the naked winter branches and the burst of bright green leaves.
Conifers do put out new leaves in spring, but it’s just a little bit more of the same. You might notice that the new needles on a fir are a little brighter than the old ones, but you would be excused if you didn’t notice any difference at all. The other reason is that the “flowers” that grow on conifers are often very small. You might be looking at a branch at arm’s length and not even see them.

Grand fir
The needles on conifers don’t last forever. To maintain their status as an evergreen, the needles only have to last over a year. Most last for several years. But they generate new needles every year. You can see the buds in early spring. Each bud contains a bundle of needles. At budburst, the needles pop out in this bundle. In many conifers, the needles remain in this bundle. In others, the needles are distributed along the twig as it grows. However, not all conifers are evergreen. Some lose their needles in the fall, like most flowering trees. For example, the larches are bare all winter and burst out in a glorious display of bright green needles in the spring.
Western hemlock
Western red cedar

Most conifers develop buds during the winter. Western red cedar is an exception. New leaves just start growing at the leaf tips.

Western hemlock cones and pollen cones

The defining characteristic of conifers is that they produce cones. It is noteworthy the conifers produce two kinds of cones: The female seed cones and the male pollen cones. We are familiar with the seed cones. Some of them are quite large. However, the pollen cones are often tiny, some of them the size of a pea, some much smaller.

Western red cedar cones and pollen cones

Most conifers produce seed cones and pollen cones on the same tree. It’s no surprise that this presents a problem for the offspring, just as interbreeding does for other organisms. Conifers have developed several strategies for avoiding self-pollination, for example, growing seed cones at the top of the tree and pollen cones in the lower branches, or having pollen cones that mature at a different time from the seed cones.

Pacific silver fir pollen cones before and after pollen release
Many conifers produce pollen cones when they are young and seed cones when they are older. A few conifers, for example, all of the yews, take a more radical approach: They produce seed cones and pollen cones on separate trees, making self-pollination impossible.

Port Orford cedar cones
Even though seed cones can be quite large, in spring when pollination happens, they are quite small, sometimes no larger than the pollen cones.  As they grow, early on they develop hard woody scales that protect the seeds inside. On the other hand, pollen cones are quite delicate. They only have to last long enough to generate the pollen, which is contained in tiny sacs. When the pollen cones are mature, these sacs burst open and release the pollen.

Ponderosa pine pollen cones
Pollen in other trees is distributed mostly by insects. This explains all those colorful flower advertisements that plants create to attract the insects. Humming birds are attracted to the flowers, too. Since conifers don’t produce flowers, how does the pollen get distributed to the seed cones? The answer is wind. When the pollen cones release the pollen, the wind carries it to the seed cones. As you can imagine, this isn’t an efficient way to manage pollination. Most of the pollen never makes its way to a seed cone. This is why conifers distribute copious amounts of pollen. You can often see clouds of yellow pollen drifting from pine trees on a windy spring day. You may also see a small cloud of pollen if you reach up and tap a cluster of mature pollen cones.

See also
Conifer Pollination
Pollen Allergies

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.