Updated: Aug 12
The official State Tree of Colorado is the Colorado blue spruce, Picea pungens. So, it's only fitting that my Patrons chose this as my first tree-centric article! In this post I'm going to cover everything from spruce identification, to foraging, to mushroom associates. First though, bare with me for a slight self-promotion before we get into the fun stuff. I recently launched a Patreon page where my followers can help support my work on Forage Colorado while also getting some cool extra perks, such as my Foraging Calendar or choosing my next website article topics, like this one! I would be grateful if you checked it out! Okay, on to the spruces!
In Colorado we have two native species of spruce, the aforementioned Colorado blue spruce, and Engelmann spruce, Picea engelmannii. These two are pretty similar and can occasionally be found growing together, but there are a few ways to tell them apart! First though, let's talk about how to differentiate a spruce from some other coniferous species. The main identification traits to pay attention to for spruces are the following:
Shape is generally conical, occasionally spire-like.
Bark is scaly and can be grey to reddish depending on species.
Needles are 4-sided, sharp, and grow around the entire branch.
Needles attach to branches on small pegs called 'sterigmata'.
Cones hang from branches and are composed of many thin scales.
The species most often mistaken for spruces in Colorado are probably firs, Abies spp., and Douglas fir, Pseudotsuga menziesii, which isn't actually a true fir but a "false hemlock"; pseudo is false and tsuga is the hemlock genus. We will go into more details when I write articles for these species, but for now here are some quick traits to differentiate them. Fir needles are flat with rounded tips, and they crowd the upper side of their branches, often bending upwards (see the subalpine fir example in photo below). Their cones are erect, standing vertically from the branches, and fall apart at maturity. Douglas fir needles are kind of a mix of spruce and fir; they are flat, a little pointed, and grow around the branches. Their cones grow hanging from the branches and have distinct 3-pointed bracts emerging from under their scales. A cute visualization for Douglas fir cones is to think of a mouse half hiding under their cone scales, its tail and back legs hanging out.
It's pretty simple to tell a spruce from fir or Doug fir, right? Well, differentiating between our two spruce species gets a little more complicated because they can look very similar until you get used to their macro-differences. For starters, "blue spruce" aren't actually always blue, they're often the same green color that Engelmann spruce exhibit, so you can't rely on color to tell these two apart! Below you will see a table showing some of the differences between the two species on both a macro and micro level! The mnemonic device that I always remember is:
"Bristly Blue, Friendly Mann"
This refers to the "friendliness" of each species if you were to reach out and give them a handshake. Colorado blue spruce needles tend to be more sharp and stiff, and grow off their branches closer to a 90 degree angle. Engelmann needles are a little less sharp and grow at more of a 45 degree angle or so. This isn't perfect, but it's a quick and easy way to remember one of their differences! Check out the table for some others!
So, now that we understand how to differentiate our spruces from similar looking species and from each other, let's talk about where they grow and why you should know how to confidently identify them! In general, our two spruces have quite a bit of habitat overlap, but they do have some preferences as well. Blue spruce will grow a bit lower in elevation, even down around 7,000ft naturally, where as Engelmann seem to prefer the slightly higher climates from about 8,000ft and up. Both species can grow all the way to tree line around 11,000 to 12,000ft, though Engelmann do seem to prefer that habitat. So much so, that they will often join the scrubby subalpine fir, Abies lasiocarpa, in krummholz form. Krummholz is German for "twisted wood", and is in reference to the stunted, scraggly, and twisted trees seen growing in the harsh conditions of the alpine habitat. Additionally, blue spruce seem to prefer the sandier habitats along mountain streams and grassy bottomlands, where as Engelmann tend to inhabit the typical spruce-fir forests found all over our upper elevations.
Outside of their natural habitats, spruces are also a very common landscape species. In fact, I can see half a dozen mature blue spruce from the window by my desk where I sit writing this article! In my experience, blue spruce tend to be the better choice for landscape trees as they tolerate the lower elevations a bit better. There are also some other species, varieties, and cultivars that are common in these settings, but those aren't really within the scope of this article. If you live in one of the urban areas around Colorado I would be willing to bet you can find a spruce without too much trouble!
Now, there are a couple very good reasons to be familiar with your spruces aside from just tree identification, though tree ID is a good enough reason on its own! They have some pretty tasty edible parts, namely the fresh new growth aptly called 'tips', and because they are a very important mycorrhizal associate for a handful of our prized edible mushroom species!
First, the foraging! Spruce tips aren't the only edible part of spruce trees, but in my opinion they're the most practical and worthwhile part. Historically, the cambium (inner bark layer) and seeds were also harvested and used as a food source, but unless you have spruces on your own property I would suggest against cutting into them for the cambium layer, and the seeds are pretty tiny! I will note that while I was doing some research I learned that spruce cambium is used during the process of making certain cheeses! That's pretty cool... but I digress, the tips are where it's at when it comes to eating your spruces!
The new growth starts to emerge from the ends of their branches around the middle of May in the Front Range and cascades up in elevation as the warmth climbs our mountains; I often see fresh new growth in July above 10,000ft. Initially, these tips will be covered in a papery husk which is soon shed as they continue to sprout. This also happens to be the best time to forage them. At this point the needles will still be pretty tightly packed together and the tips will be nice and tender. If you're impatient you can pluck the husks off manually before collecting the tips, I usually do, or you can practice your meditation and wait for them to fall off on their own. Before you go to crazy though, try a couple fresh! Each tree has it's own unique flavors; some are more bitter than others, some are lemony, while others are very piney. If you like them fresh, you'll like them in your cooking as well!
As you can see from the photo below, on a healthy mature tree each branch will have several points of new growth. Not all spruces will exhibit this type of growth, especially the naturally occurring ones in the mountains, but if you have access to some healthy urban trees you could definitely see this sort of production! Remember to practice your sustainable foraging though! Spread out your collecting, never taking too many from one area or a single tree, and never taking the terminal growth at the top of a young tree as this will stunt its growth. Also, if the tree you're collecting from is on your property you can strategically collect tips from certain areas if the new growth is starting to encroach on some territory where it doesn't belong. Oh, and a note, you may see some strange growth and coloration on some tips. This is a gall caused by an insect called an adelgid. It's pretty common, just skip the infected tips.