From a distance, many conifers of varying species appear similar. But close observation of the tree's foliage and cones reveals distinguishing characteristics.
Usually, separating a conifer from a broad-leaf tree is a simple task. Conifers often feature cones (a variety of flower) and bear narrow leaves or needles designed to retain water. The crown (upper leaf-covered segment) of a conifer is also distinctive; it is generally pyramid-shaped and slender. Most conifers are evergreen.
The greater challenge lies in differentiating one conifer from another.
Over 80 species of pine exist, which are divided into two general categories: hard pines, also called yellow pines or pitch pines, and soft pines, also known as white pines.
Like other conifers, pine trees produce male cones (less than an inch in length, soft, and polliniferous) and female cones (several inches in length with thick, hard scales).
Pine needles are several inches long and dark green and grow in clusters or five in hard pines and in clusters of two or three in soft pines.
As the spruce is a member of the pine family, spruce and pine trees tend to be difficult to tell apart. The geometry and arrangement of the needles and the character of the cones provide clues.
According to Dr. Grant Wood of the University of Saskatchewan, spruce needles in cross section appear either square or triangular. If you tried to roll a spruce needle sideways between your pointer finger and thumb, the needle would roll easily, somewhat like a HB pencil.
Spruce needles, unlike pine needles, grow individually out from the twig and not in clusters.
The cones of a spruce tree have thin, fish-like scales, in contrast to the woody, rigid scales of a pine.
The fir tree is very similar to the spruce, but one important point of distinction is the shape of the needles: fir needles appear flat in cross section.
Unlike the pendant cones of other members of the pine family, mature female fir cones stand erect upon the branch. The fir is the only conifer that consistently bears this trait.
True Cedar, Juniper, Cypress and Arbor-vitae
Unfortunately, "cedar" is a very imprecise term, serving as an umbrella for members of the cypress, juniper and true cedar families. With a few exceptions, trees designated as "cedar" in North America have flat, feather-like leaves (no needles) and small female cones (about half an inch in diameter).
True cedars, which are endemic to the Middle and Far East, have barrel-shaped cones and spruce-like needles.
The juniper, unlike most other "cedars" of North America, tends to be shrubby and prickly (with needles).
The arbor-vitae (Latin for "tree of life") fits the description of the North American "cedar" but is a member of the cypress family.
Douglas-fir and Hemlock
The Douglas-fir has presented taxonomic challenges to arborists and botanists for centuries, due to its similarity to members of other conifer families.
To distinguish the Douglas-fir from the hemlock or true fir, observe the cones, which hang from the branch (unlike a true fir's cones). Each scale of a Douglas-fir cone also bears a three-pronged bract (specialised leaf), which resembles a dragon's tongue.
The hemlock tree's cones bear no bracts, and its needles are soft and non-clustered. The western hemlock, common in the Pacific Northwest, usually droops at the peak of its crown.
The Others: Redwood and Larch
Today, the redwoods are most common in a narrow belt along the coast of northern California and southern Oregon.
The redwood requires a specific set of environmental conditions in order to thrive: a cool, consistent climate with summer fog and heavy winter rains; alluvial soil near a water source; and generally a low elevation.
The redwood's needles are similar to those of the hemlock or spruce, but redwood cones are characteristically tiny (about one inch long). However, given that some species of redwood can grow to be over 300 feet tall and ten feet wide, the foliage probably won't be the feature that most grabs your attention.
The larches, unusual among conifers, are deciduous (shed their leaves once per year). Larch trees bear soft needles up to two inches in length and light-green or yellowish in colour. They prefer dry mountainous regions, and have greyish-brown scaly bark.