Washington is proudly known as the "evergreen state", which means that we have an awesome diversity of pines here. They offer versatile medicines all year long, including pine needles, pine sap and pine pollen. Botanically, many of these trees are in the Pine family (Pinaceae), and are further divided into several genuses (subcategories), which we'll get into later.
Pine sap leaks out of the tree in response to bark trauma (beetles, bullets, axes, knives etc). It's very sticky, and is usually in varying states of hardness. It's best to harvest it into a glass jar, or into wax paper, since it'll stick to anything else.
I love to infuse pine sap into oil (by heating it gently in the oil on the stove) to make salves, which have a heavenly smell. You can combine it with other plants or keep it alone.
Pine sap is very antimicrobial, so it's great for wounds and cuts that are ready for salve (serious wounds need some care first). I like to put the salve on cystic acne. It's also great for sore joints-a good local combo is black cottonwood oil and pinesap oil. Yum. People also use pine sap internally for lung congestion and sore throats, though I haven't used it for that. Some species of pines are too harsh for internal use, so go for the sweet, gentle kind (not the kind that smells like turpentine).
Pine needles can be harvested all year long, but are best in the spring when the new growth comes out (see picture of Douglas fir tips). The needles are very high in vitamin C, and have mild antimicrobial properties that makes it a good medicine for sore throats. They were used, per recommendation of the Indians, by early American settlers to get through the winter without dying from sickness. I love to make pine needle honey, cordials, elixirs and syrups--all of which are incredibly delicious.
Pine pollen has gotten popular as of late as a superfood and a testosterone normalizer. Pine pollen is, after all, the male reproductive part of the plant. Pollen in general is very high in protein and micronutrients.
This is best harvested in the spring when allergies are at their height. Have you ever seen the wind blow while the pines are releasing pollen? It's yellow! When you see that, get out and harvest. The best way to harvest is either to clip off the very tip of the branches where the catkins grow, or to put a bag over the whole thing and give it a shake. The pollen will fall right into your bag.
The best trees to harvest pollen from are true pines (Pinus spp), like Lodgepole pine, Ponderosa pine and White pine. You'll never harvest any quantity of pollen from other genuses.
Spruces (Picea spp.):
Spruce has such a unique and delicious smell that I highly recommend seeking it out and making medicine out of it. Just yesterday I made a blue spruce needle honey which I have high hopes for. I have also tried spruce bitters (made by my uncle!), which was delicious. Our major native spruce is Sitka Spruce (Picea sitchensis), though I most often use blue spruce (Picea pungens), which is common in parks and gardens. Spruces have VERY sharp needles, so wear gloves when harvesting and chopping.
Hemlock (Tsuga spp.):
Our most common hemlock is Western hemlock (Tsuga hertophylla). Personally, I don't use it as medicine, but it's a good tree to know, since many mushrooms prefer hemlock forests, and hemlock wood. Note that this "hemlock" is not related to "poison hemlock" (Conium maculatum), which is in the carrot family, and is highly poisonous. The needles of these trees can be used for tea while camping, for example, and will not kill you!
True Pines (Pinus spp.):
Pines are easily identified by the "needle packets", which means that 2-7 needles will be bundled up by a little brown thing. Pines also tend to have relatively long needles, and large cones. They make great sap, which tends to smell strongly, and are the best trees to harvest pollen from. You can also make pine needle baskets from the longer needles, like Ponderosa pine.
Douglas Fir (Pseudotsuga menziesii):
Even though it's called a "fir," Douglas fir is actually in a separate genus. Douglas fir makes delicious-smelling, clear sap, and the tender green needle tips are one of the most delicious things EVER. I like to add sugar and vodka, 1 : 1, to a jar packed full of Doug fir tips, which makes a delicious addition to cocktails or hot water. This is the most abundant tree in Western Washington (that's a subjective claim), so it's a good one to learn. I've made plenty of Douglas fir needle tea on camping trips, and it's always a crowd pleaser.
True Fir (Abies spp.):
The most obvious way to idenfity this genus is that the cones point toward the sky, while most others hang toward the ground. We have many firs in the PNW, including Subalpine fir (Abies sitchensis), Grand fir (Abies grandis). Firs are very aromatic and make delicious medicines.
Larch (Larix spp)
I have never used larch as medicine, though presumably you can.