GardenLine | Trees and Shrubs | Fir, Pine or Spruce - Which Do I Have?

Grant Wood was an instructor with the Department of Horticulture Science. This column is offered as an extension service by the Division of Extension and Community Relations and the Department of Horticulture Science, University of Saskatchewan.

Homeowners who call GardenLine often ask us to help them identify the coniferous trees in their yards. The most common large conifers in Saskatchewan are fir, pine, and spruce. We hope that this article will help you tell them apart. The main means of identifying them is by their needles and cones. It is also possible to identify them by their bark and shape, though with less reliability. In passing, it is worth mentioning that the larch common in Saskatchewan is classified as a conifer because it has cones, but it is not an evergreen: it loses it needles in the fall. The Douglas fir, which is not fully hardy in Saskatchewan, is another tree some people may find tricky to classify. Though its name implies it is a fir, it is actually not a true fir.

Needles

Like deciduous trees, conifers can be identified by their "leaves." The "leaves" of conifers are of course their needles. On pine trees, the needles are arranged in clusters, with 2, 3 or 5 needles per cluster; spruce and fir have their needles attached individually to the branches and branchlets.

To tell spruce and fir trees apart, it helps to know that spruce needles appear square in cross-section, whereas fir needles appear flattened. The needles of Norway spruce are an exception, with three sides instead of four. Needles on fir trees are often blunt and notched at the outer end and usually have two white bands on the underside of the needles. Spruce needles can be blunt as in the white spruce, or sharply pointed as in the Colorado spruce. The needles on both spruce and fir trees are spirally arranged, but the branchlets on fir trees are flat on one side as compared to the rounded appearance of spruce tree branchlets. Spruce needles are attached to small, stalk-like woody projections. When needles are shed, these projections remain. As a result, the branchlets of spruce trees feel rough. Fir branchlets lack these projections, and thus have smooth bark. The color and length of needles are not reliable means of identification; these can vary from tree to tree, depending on cultural conditions and the planting site.

Cones

Cones are made up of scales attached to a center stalk. In between the overlapping scales the seeds can be found. The difference in cones can be seen by the scales. Pine cone scales are woody in nature, with a rigid feel. In contrast, spruce cones have thinner scales than pine cones, which gives them a less rigid feel. Rigidity varies greatly within the spruces. Length of cone is not a reliable way of differentiating one type from another; the length can vary greatly from tree to tree. The margins of the scales can be used to differentiate species of spruce and pine. In some species, the margins are entire and rounded as in the white spruce, while in others they are rough and notched as in the Colorado spruce.. Some pine scales have a small prickle on each scale to further help identification. Most spruce and pine trees retain their cones for a few years; thus it is common to see new and old cones still attached to a tree. A number of pines will retain their cones for many years. Fir cones are erect, unlike the pendulous cones of most spruce trees. In fir trees, the scales on the cones are deciduous; that is, in the autumn, the scales fall off, leaving the erect center stem attached to the branch. You will see these erect center stems near the top of the fir tree. Though it won't help you to tell conifers apart, just for your information: the cones I've been discussing are the female reproductive portions of the tree. The male cones are formed in the spring near the branch tips and are often mistaken for reddish buds. These cones are short-lived. Female cones are produced in the summer and are not fertilized until the spring of the next year. The seeds can be shed later the same fall or are sometimes not shed for a few years. Most female cones are found near the top of the tree.

Bark

Bark alone is not a fully reliable indicator of the type of conifer you have. The surest way to identify conifers is to examine the needles and cones along with the bark. In general the bark of pine trees is smooth on young trees but develops a flaky, reddish-brown colour with age. Scots pines have a particularly orange/red peeling bark. White pines can have smooth bark, even when mature. The bark on spruce trees is generally rough to touch and becomes furrowed and scaly with age.

Fir trees have smooth bark that is often grayish when young, but develops a furrowed appearance as it ages.

Shape

All conifers shed needles - sometimes this shedding is slow, but most commonly it occurs all at once in the fall. Because the oldest needles are shed, the "inner" areas of the tree closer to the trunk become less dense than the outer areas. Pine trees usually shed three-year-old needles, whereas spruce and fir shed needles that are four to five years old. Partly for this reason, pine trees will usually appear thinner and less dense than spruce and fir. Conifers of a given type (e.g., pine) vary greatly in shape, so it is not possible to identify a tree's type by its shape. Size as well as shape can differ from tree to tree depending on the cultural conditions and actual planting site. For a more detailed identification of species and varieties, consult The Manual of Cultivated Plants by L. H. Bailey, Trees and Shrubs for Northern Gardens by Leon C. Snyder, or Woody Ornamentals for the Prairie Provinces, by R. H. Knowles.

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.