Thuja occidentalis, a species of conifer native to eastern North America, is known among woodsmen as “cedar” or “white cedar”. These common names are firmly entrenched in New England and Canada and there is nothing to be gained by pointing out that the tree is not a true cedar.
Horticulturists use another common name for the tree, calling it “arborvitae”, literally the “tree of life”, a name that has its origin in the early history of North America’s exploration. It was in 1534 that French explorer Jacques Cartier and his crew, sent by King Francis I to the New World in search of a new route to Asia, were forced by thick ice to spend their first hard winter on the continent near present day Quebec. Subsisting through the long winter on a diet devoid of fruits or vegetables, many of the crew died from scurvy, a lack of vitamin C, and all would have perished had it not been for a friendly native who, recognizing the ailment, prepared a tea from the needles and bark of a tree. The tea, high in vitamin C, had an immediate restorative effect. Within eight days, an entire tree had been stripped bare and the frenchmen were cured of scurvy. Cartier named the life-saving tree “Arborvitae” and eventually brought specimens back to France, making Thuja occidentalis the first North American conifer to be grown in Europe.
Arborvitae’s roots are also firmly anchored in New England’s past. In The Maine Woods, Thoreau described how Native Americans constructed a carrying harness from arborvitae shingles and bark. The canoe frames were also made from arborvitae wood for the same reason that lumber camps in the North Woods have shingles made from arborvitae: its wood resists decay for decades.
Arborvitae, some upward of 50 feet in height, grace Marjorie’s Garden and the woods around it with their strongly tapered reddish-brown trunks, long upward-turning branches, and fan-like sprays of scale-like needles. They belong to a cohort of mature arborvitae, most of which grow along streams that empty runoff into the nearby Union River. But seeds sprout where they are sown and some of the arborvitae, including some of those in our garden, manage to survive on drier ground, sending their roots deep in search of water. In other areas of the garden, small spindly trees grow in a thin soil covering a layer of thick granite, or ledge, as they call it in Maine. These small size of these trees, their roots seeking water held in the cracks of rock, belie their age.
The arborvitae in Marjorie’s Garden are my favorite conifers, changing their appearance with the seasons while harboring a multitude of bird and insect life. Spring through summer, their sprays of scale-like leaves are a soft apple green, and apple-scented when crushed. Many different birds use the dense summer foliage for nesting, including several warblers (northern parula, black-throated green, blackburnian, black-and-white, and magnolia), white-throated sparrows, yellow-bellied flycatchers, ovenbirds, winter wrens, Swainson’s thrushes, and golden-crowned kinglets.
In late summer, clusters of oval, pea-sized cones appear among the foliage and slowly ripen from green to a warm brown. These cones persist through the winter, their seeds a favorite food of redpolls, junco, pine siskins, grosbeaks, crossbills, and other birds.
In late October, as older pine needles are turning golden, the scales on older arborvitae branchlets, those about to be shed, turn a rich cinnamon brown amid the apple-green of younger branchlets. Come winter, the remaining scales take on a yellow-green hue, a pleasing contrast to the dark greens of nearby pines and firs.
In addition to the bird life associated with arborvitae, it also serves as a host plant for various insects and their predators. The black carpenter ant and red carpenter ant develop chambers within the rotting wood of the trunk and branches of older trees. In so doing, they become prey for pileated woodpeckers that excavate cavities in the tree to feed on the ants. Larvae of several moth species feed on the scale-like leaves while other moth larvae attack young seedlings. Additional feeders include the larvae of sawflies, scale insects, aphids, plant bugs, weevils, and beetles, as well as several species of mites. While all of these arthropods are herbivores, they are also food for nesting birds.
Despite the longevity of most arborvitae, many living for 200 years and some much longer, one of the tallest arborvitae in Marjorie’s Garden had been in decline for several years, the cause unknown. We decided to cut it down in 2012 after noticing that red squirrels were entering the trunk at the bottom of the tree and exiting through a hole several feet higher. The tree grew very close to the parking area and we feared the worst, so an arborist friend cut it down, leaving a twenty-foot tall stump with a hollow core, a playground for the garden’s squirrels. We watch them chase each other through the hollow bore of the stump.
Over the years, long before Marjorie’s Garden, this old tree and several others had sown seeds throughout the area, the small seedlings persisting as such for decades in the shade of tall spruce, waiting for a gap in the canopy. When we discovered any of these young arborvitae hidden within a dense stand of spruce at the edge of the garden, we grabbed the pruning saws and created that canopy gap, liberating the small seedlings, wishing them a long life. Now there are several small arborvitae in the garden and surrounding area, some just beginning a long life of producing their own seeds.
Horticulturists have discovered and propagated more than 200 forms of arborvitae varying in foliage color, growth habit, and growth rate. Many are slow-growing forms of the species, often called dwarf conifers. Some are short and stout, others pendulous in habit. Many grow only one to three inches a year, never reaching more than a few feet in height, much like the rock-bound trees in Marjorie’s Garden.
Among the tree-sized cultivars are several selections, including ‘Nigra’ and ‘Wintergreen’, grown for their dark green winter color which some prefer over the bronzy winter color of the species. A cultivar called ‘North Pole’, selected from a population of ‘Wintergreen’, is a very narrow columnar tree with excellent hardiness and dark green winter foliage color. ‘North Pole’ grows only 15 feet in height, an ideal size for shrub borders and even large containers.
In any of its many forms, Thuja occidentalis is deserving of the common name “arborvitae”, “Tree of Life”, if no longer for its medicinal value, then for the many birds and insects that depend on it. We feel fortunate to include arborvitae as part of the garden’s food web.