Dakota Gardener: They are not all pine trees

As I sat down to write this column, I realized that it might be a bit confusing. As a scientist and a communicator, I try to be precise and specific in my word choice. That’s a great goal, but it’s not always attainable when working in natural systems. Scientifically, there’s always an exception. Nevertheless, I hope you find this useful.

It was my first year at NDSU, and I received a phone call from a client. He said, “I have a fir tree. I think it’s a spruce and it’s loaded with pine cones.” He wanted to know if there was anything wrong with it.

I was taken aback at first, but through some back-and-forth discussion, we figured out what was going on. It was a spruce tree that had a lot of spent pollen ‘cones’. This is normal behavior for a tree at that time of year and nothing to worry about.

But I was still confused about his use of the words fir, spruce and pine, to describe a single tree. Fir, spruce and pine are all conifers, but each one is unique and they can’t interbreed. They’re all different species.

So, it’s time for a brief lesson on the conifers of North Dakota.

The most common conifer trees planted in North Dakota are pines (ponderosa and Scotch pines) and spruce, such as Colorado (blue) spruce and Black Hills spruce. Yes, there are certainly others mixed in, but these are the most common. They’re all conifers but they’re not all pines.

Pine trees are in the genus Pinus, and they have relatively long needles that are held in clusters called fascicles. Ponderosa pine generally has two or three needles per fascicle and the needles very long – 4 to 9 inches long. Scotch pine trees have two needles per cluster, the needles are about 1.5 to 3.5 inches long and they’re twisted around each other.

Spruce trees are in the genus Picea and they have shorter needles that are held individually on each twig. Colorado (or blue) spruce needles are about 1 to 1.5 inches long and are really sharp. Blue spruce is definitely a poky tree! Black Hills spruce has needles that are a little shorter, about 0.75 to 1 inch, and they’re not sharp.

Unfortunately, not all blue spruce are blue. Sometimes they’re more greenish and even the Black Hills spruce can be a little blue. So we use other characteristics to properly identify these species.

Correct tree identification is a challenge but it’s critical. For example, tree species are sometimes very specific in where they can grow. If we tried to plant the spruce or the pines in a wet site, the trees would die. Only a limited number of conifer species can grow in wet sites. Most will drown out if their root systems get flooded.

Also, certain insects or diseases are specialists and hit only specific types of trees. Yellow-headed spruce sawfly is an insect that attacks only spruce trees. It doesn’t hit pines. Western gall rust, on the other hand, can be found on ponderosa and Scotch pines, but not on the spruces.

I try not to get too bothered about improper usage of the scientific terms used in identifying trees. I’m a forester and trees are what I study, day in and day out. It’s a pretty unique occupation, especially in North Dakota. And in all my 20 years at NDSU, I still haven’t figured out how to tell the difference between wheat and barley. Something about the beards or the awns?

There’s always something new to learn.