Conifers figure prominently during this time of year. Because most conifers are evergreen, they will continue to provide color to the winter landscape after the deciduous trees have lost their leaves. Conifers also are a part of the Christmas tradition.
There are two main groups of seed plants: Gymnosperms (from the Greek words gymnos “naked”and sperma “seed”) and Angiosperms (from the Greek words angeion “vessel” and sperma “seed”). Conifers are gymnosperms and like all gymnosperms, conifers have needle-like or scale-like leaves and use cones rather than flowers to reproduce. Their name means “cone bearer.” Cones are a woody structure that keeps the uncoated seeds safe until they are mature. Gymnosperms have no flowers or fruit. Angiosperms have both and their seeds are enclosed in a fruit (vessel) and, thus, are covered and not “naked.”
The first seed plants to evolve were the Gymnosperms during the Devonian Period (about 382.7 to 358.9 million years ago). Conifers first appeared during the end of the Carboniferous Period ( about 358.9 to 298.9 million years ago) and the modern types of conifers began to evolve in the Mesozoic Era (250 to 65 million years ago), the time when dinosaurs lived. Conifers were the dominant plant right before Angiosperms started to appear. Angiosperms evolved during the Mesozoic and soon became dominant over most of the world except for lands in the far north or at high elevations. The reason we now see so many conifers in this region is because humans have planted them! Conifer leaves offer more protection against extreme conditions (colder and dryer) because their leaves (called needles) have smaller surface areas than broad leaves and also have a cuticle (thick waxy covering) on their outer surfaces. Both these adaptations reduce water loss through evaporation. Conifers do shed their needles, just not all at once. The oldest needles are shed sometimes slowly, but usually it occurs all at one time in the fall. The needles turn yellow before falling.
Conifers are the largest of the gymnosperm divisions with 630 species spread across the world except for Antarctica. Pines, firs, spruces, junipers, redwoods, yews, cypresses, larches, and cedars are examples of conifers. Conifers can grow to be immense and among them are the world’s largest trees. The largest is a giant sequoia (about 1487 cubic meters), the widest is a cypress (11.42 meters) and the tallest is a coast redwood (115 meters). The oldest tree in the world is a bristlecone pine (4,700 years old).
Like all gymnosperms, conifers reproduce via cones. The male and female cones are borne on the same tree. The male cones are usually found on the bottom of trees and the female cones are usually found at the tops. The ones most familiar to us are the larger female cones. The smaller male cones produce great amounts of pollen grains which when released are carried by the wind to female cones on other trees. The seeds are found on the surface of the female cone’s “leaves”. Cones are comprised of scales (leaves) attached to a center stalk. Usually seeds are released from the cone when it gets warm (sometimes this requires intense heat from fires!). Warmer temperatures favor germination. After seed release, the cones fall to the ground. Female cones come in many different shapes and sizes, while the male ones look very similar.
Pine, fir and spruce are common conifers in this area. How do you tell them apart? The easiest way is to look at the needles. Comparing cones and considering tree shape will also help.
A common pine in this region is the Eastern White Pine (Pinus strobus). It is a large tree with a straight trunk and has a feather-like shape, with tiered, horizontal branches. One row of branches is added every year. The branches turn up at the ends. Mature female pine cones are reddish brown. The scales are woody and rather rigid. The light-green to bluish-green needles are found in clusters of 5, growing from a single point on a branch. White pine needles are soft compared to fir and spruce.
Another common tree in this area is the Blue Spruce (Picea pungens). This tree is medium to large in size with a distinctive pyramidal shape and branches to the ground. If you drew a Christmas tree when you were a child, it would have looked like a spruce! The light blue-grayish needles are short, sharp and stiff. The species name pungens is Latin for “sharply pointed” and refers to the needles. They are square-shaped and jut out in all directions from the branches. You can easily roll them around with your fingers. Each spruce needle is attached to the branches via a tiny wooden projection (you might need a magnifying glass to see these stalks on smaller branches). The cones are light brown and have flexible scales. They are cylindrical in shape and up to 4 inches in length.
And finally, an example of a common fir tree found here is the Balsam fir (Abies balsamea). Abies is Latin for “silver fir.” Balsam is an aromatic resinous substance that is exuded from some trees. This tree has aromatic foliage and is the most fragrant of the Christmas trees. Crush the needles of the Balsam fir to get a good whiff of balsam! The needles are a rich green and are retained for a long time after cutting – a plus for Christmas trees. They are flat, dark green with a paler underside patterned with a few white lines and cannot be rolled between your fingers. Each needle is attached directly to the branch like the spruce but not via a woody stalk. The tree is conical shaped with a crown shaped like a spire. The cones, before becoming golden brown, can be blue, purple or green. Cones grow upwards – this makes it easy to identify firs.
So now armed with the information in this article, you should be able to walk around the Park or in your neighborhoods and identify at least 3 conifers! If you interest is piqued, there are lots more types of conifers which you can research on your own!