Wednesday, March 11, 2015

Tree of the Season: Incense Cedar

The incense-cedar graces many Bay Area gardens with its shade, beauty, and intriguing fragrance. Calocedrus decurrens, its Latin name, means beautiful cedar. The striking contrast between the vibrant greens of its leaves and the trunk’s rich reds creates a pleasing aesthetic further enhanced by the relaxed elegance of the weeping foliage. The beauty of this tree is not confined to the realm of the visual. The incense-cedar gives off a distinctive fragrance that fills the air with a pungent aroma strongly reminiscent of grade-school classrooms and the unforgettable smell of the pencil sharpener. In my youth, and still largely today, pencils were made from the soft, and distinctively fragrant wood of Calocedrus decurrens. 

The incense-cedar is not a true cedar (thus the hyphen). The so-called “true cedars” are native to the Mediterranean and the Himalayas, and are members of the genus Cedrus. These include the majestic Deodora and Atlas cedars, as well as the famous Cedar of Lebanon.

The incense-cedar, which may live a thousand years and attain a height of 150 feet, is a true California native. It evolved in North America, and its current range extends from the Cascade Mountains in northern Oregon, through the Sierra Nevadas, down to the Sierra San Pedro Matir of Baja California. Throughout its range it has been important in the lives of Native Americans.  The Klamath tribe of Oregon wove its bark into baskets. The California Paiutes made infusions of its leaves for colds. The Round Valley tribe of Mendocino Country used leaflets as flavoring when leaching acorn meal. This species has provided Native Americans with food, shelter, clothing and music.  

The incense-cedar’s natural resistance to rot made it very useful both in antiquity and in modern times. Homebuilders use it for siding, decking, moulding, and interior paneling. Landscapers use its chips and bark for mulch. Its wood is made into furniture, shingles, and railway ties. Sawdust and wood scraps help fuel co-generation of electricity.

The softness of the wood and its resistance to splintering make the incense-cedar ideal for encasing pencil lead. However, these qualities also make the wood fragile and brittle, and potentially somewhat problematic as an urban landscape tree. When it grows as one trunk from a thick base to a single pyramid-shaped crown, the incense-cedar is relatively stable; it requires little work other than the periodic removal of deadwood. But if the trunk of the tree divides into multiple columns, or has large branches which turn up and rise parallel to the trunk, the tree has structural problems that make it vulnerable to column failure. After some recent winter storms, Brende & Lamb looked at many incense-cedars that had shed branches and sometimes entire columns. Most of the failed trees suffered from a malady of tree anatomy called included bark. This structural defect occurs when the bark at the crotch folds inward, and interrupts the continuity of the fibers supporting the columns.

Good pruning can ameliorate many structural problems. Co-dominant stems (more than one column of roughly the same diameter) are more likely to fail than trees with a single leading column. Sometimes reducing one of the competing leaders can minimize the hazard. If column removal is not advisable for aesthetic or functional reasons, it is often possible to cable the multiple stems together. However, individual trees are so unstable that removal is the safest alternative. Whatever you do, do not top these trees. Topping a cedar will eventually produce many unstable columns multiplying the risk and, ultimately, the expense of keeping the tree. Preventative medicine is almost always less expensive and more effective than later surgery. If you plant an incense-cedar, choose nursery stock with only one trunk and no crotches with included bark. Remember that a seedling cedar can grow to over a hundred feet and that tall trees may cause view concerns for yourself and your neighbors.

Calocedrus has graced the California landscape for almost 200 million years. With a little forethought and good pruning, it can continue to bless Bay Area gardens with the subtle fragrance of childhood. It takes a little effort to live at peace with this large California native, but its bounty of colors, shapes, and scents make that effort worthwhile.

If your trees and shrubs need a little TLC - call us to schedule a free estimate.

Blaine Brende & Joe Lamb
510-486-TREE (8733)

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