Rare is the yard that doesn't contain at least one "Christmas tree," as people who don't know one conifer from another are apt to lump members of this major group of landscape plants.
And yet, once you recognize the differences you'll quickly be able to tell one from another and choose the types best suited to particular situations.
Conifers are a mainstay of the garden, their tall, stately presence infusing it with structure and even a sense of power. In winter, when deciduous trees are bare and the landscape stands bleak and cold, the blues and greens of conifers spice it with color and a warm glow of freshness.
Conifers, though, are a vast and varied lot. It helps, therefore, to have some guidelines to sort out one from another.
To qualify as a conifer, a plant must bear cones. Some "cones," however, are better described as berries. The most notable examples are the red fruits found on yews or taxus and the midnight-blue berries displayed on junipers.
Conifers also are loosely referred to as "evergreens," but not all of them are, a point to keep in mind if you are looking for year-round foliage.
While their foliage is characteristically needled or narrow-leaved, such conifers as larch, bald cypress and dawn redwoods lose it in the winter. (Dawn redwoods, by the way, belong to the Metasequoia genus. The true redwoods, the giants most closely associated with the great redwood forests of California, retain their foliage year-round. These redwoods are classified as Sequoias or Sequoiadendrons, depending on the species.)
Its name notwithstanding, the bald cypress with its curious knees or rootlike protuberances is not a cypress (or Cupress, if you use the botanical name), but a Taxodium, T. distichum nutans, to be exact.
The bald cypress, notes Miles Patterson Jr., president of Manor View Farm, a wholesale nursery in Monkton, is an extremely fast-growing tree, increasing in height by 5 feet a year. In 15 years, it may reach 75 to 80 feet tall, he says. Given its preference for swampy habitats, the bald cypress leads Mr. Patterson's list of best trees for wet conditions.
To confuse matters further, the trees commonly called red cedars are actually junipers.
The real cedars, or Cedruses -- their botanical name -- encompass a group that to my mind are the most elegant and graceful of all conifers, if not of trees universally, and deserve an honored place in the garden. Principally composing the genus are the Atlas cedar, the deodar cedar and the biblical cedar of Lebanon.
But to give junipers their due, Mr. Patterson rates them among the most varied of all conifers, given their wide assortment in form and texture, and in color from dark green to blue to yellow. Junipers suit, he declares, "just about every use you can think of."
For starters, he mentions mass and foundation plantings, ground covers and focal points. Undemanding, junipers are easy to grow and withstand drought and cold better than most conifers.
Ed Hogarth, a landscape architect and nurseryman in Jarrettsville, and a teacher of landscape design at Harford Community College, calls spruces, pines and hemlocks
"major" trees. They grow to enormous size, he notes, and are commonly used as windbreaks or to screen an ugly view. This group of conifers too, he says, offers enormous variations.
Spruces, Mr. Hogarth explains, are more pyramidal than pines and will therefore fit into less space. (The botanical name for spruce is Picea; for pines it is Pinus.) Spruces do well in this area generally, he says. Like all conifers, they crave sun, "the more the merrier." They also need good drainage and will thus fare better on a hill than in a valley.
However, spruces in crowded quarters or deprived of sufficient sun quickly lose their lower branches. In close spaces, Mr.
Hogarth would sooner plant hemlocks because they take to shearing and can therefore be kept compact. Mr. Hogarth is partial to hemlocks anyway, calling them the softest evergreens you can find.
Of all conifers, the spruce, for its characteristic Christmas tree shape and its blue hue, is the one most commonly recognized. But the genus includes white and black species (the terms are not an indication of color) as well as many others, all generally described as green. But if you're after blue, Mr. Patterson offers some hints for selection.
The name Colorado blue spruce (Picea pungens glauca), he says, is generally given to trees grown from seed. Ten percent will be blue, the others will be "green as grass." However, it is the grafted types that are brilliant blue. To ensure that your spruce will be that color, Mr. Patterson says, ask for a "named" variety such as Hoopsi, Moerheimii or Kosters. They will retain their hue throughout the year, and be so blue they appear to have been sprayed. Grafted specimens, however, cost two-thirds or more than spruces raised from seed.
Readers interested in conifers, particularly the rare and unusual types, might join the American Conifer Society. For information, contact Carville M. Akehurst, the executive director, at 256-5595 or P.O. Box 314, Perry Hall, Md. 21128.
Recommended as a reference is "Conifers," by Van Gelderen, which has 1,190 color photographs. The book costs $65 plus $3 shipping, and can be ordered from the publisher, Timber Press, 9999 S.W. Wilshire, Portland, Ore. 97225.