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Beautiful Bark

Originally published in the Ithaca Journal, May 2002
By Mary Hirshfeld

October is a visual treat, a bouquet of brilliantly colored foliage and fruit. However, once autumn has passed, the monotones of the long, gray Ithaca winter settle in. Yet plants can still provide color and interest throughout the winter. Bark, an ornamental attribute that is usually overlooked during the summer, can add color and variation to the snow-covered winter landscape.

Cornus Alba
Several of the shrubby dogwoods-namely the Tatarian dogwood (Cornus alba), the bloodtwig dogwood (Cornus sanguinea), and the red osier dogwood (Cornus sericea), offer cultivars with bright red, orange, or yellow bark. Cornus alba is native to China and Korea, while Cornus sanguinea is a native of Europe, and Cornus sericea is North American. In their respective native habitats, all are denizens of moist soil. Yet they make remarkably adaptable landscape plants which, although at their best with ample moisture, will tolerate dry conditions and perform well, either in sun or partial shade. All three species are essentially interchangeable as landscape plants, suckering to form colonies of slender red stems that can brighten the winter landscape considerably.

Cornus ALba Bloodgood
However, among the three, many cultivars have been selected which broaden the bark color palette to include yellow, orange, and varying shades of red. The Siberian dogwood (Cornus alba 'Sibirica'), is probably the most widely grown red-twigged shrubby dogwood. Unfortunately, plants sold under this name are not uniform. Because some are better than others, it is best to inspect the plants at a nursery to make sure you are acquiring ones with rich, red bark. From the J.C. Raulston Arboretum in North Carolina comes an excellent, vigorous selection with very bright blood-red stems, aptly named 'Bloodgood'. Cornus Alba Buds The planting in Plantations' winter garden, a real stand out in the winter, has also proven quite resistant to the disfiguring leaf spot that plagues most shrubby dogwoods during the summer months. A relatively new yellow-twigged dogwood (Cornus alba 'Bud's Yellow') was selected for its resistance to twig canker, a disease that causes unattractive brown patches along the stems. This disease is very common on the widely grown yellow-twigged Cornus sericea 'Flaviramea'. Better to find 'Bud's Yellow', plant it and enjoy its rich yellow unblemished stems during the winter months!

Cornus Sanguinea Midwinter Fire
Corus Sanguinea Midwinter Fire Two recent introductions, Cornus sanguinea 'Midwinter Fire' and 'Winter Flame', display stems that shift from red to orange to yellow, reminiscent of the color gradations in the flames of a cozy campfire. Both are twiggier, stiffer, and slower growing than other selections, so planting them quite close together results in the best display. Both develop nice pale yellow fall leaves, in contrast to the more common and not very showy deep purple-red of most shrubby dogwoods. Cornus sericea 'Cardinal', a recent introduction from the Minnesota Landscape Arboretum, flaunts bright cherry red stems that are distinctly lighter and brighter than the mahogany red stems typical of most other shrubby dogwoods.

All shrubby dogwoods, however, tend to display nondescript brownish or greenish-yellow twigs during the summer, the bright color developing only as the cool weather settles in. These plants are best used in large drifts, where the sheer number of stems makes a bright splash against the snow, or where they can anchor a grouping of white-stemmed birches to make a durable and pleasing winter display. Unlike many trees that require a certain degree of maturity before displaying their unusual bark patterns, shrubby dogwoods loose their bright stem coloration with age. As the twigs mature and increase in girth, the bright color is lost and the bark becomes brownish and drab. An early spring thinning, cutting a portion of the stems back to three to four inches above ground level, will ensure an annual crop of vividly colored young stems to enjoy over the coming winter.

Salix Coral Willow
Salix Coral Willow With diligent and persistent spring pruning, many arboreal willows can be kept at shrub height and encouraged to produce dense stands of colorful young twigs. For example, if left to its own devices, the coral bark willow (Salix alba 'Britzensis') will develop into a 50-foot-tall, rather uninteresting tree with rough yellow-brown bark. However, if regularly coppiced, or cut back to three or four inches above ground level, it can be maintained as a multi-twigged shrub with vivid coral-red bark. As with the shrubby dogwoods, the young stems are the most vividly colored, so regular pruning is required to ensure a steady crop of young stems. Once Salix alba 'Britzensis' Salix alba 'Britzensis' the plant has established a strong root system, it can produce five- to seven-foot stems in one season, so annual coppicing may be needed to keep it within bounds. Salix Scarlet CurlsOther willows that are worthwhile additions to the
Salix Scarlet Curls
winter landscape include Salix 'Scarlet Curls' the corkscrew willows. These produce red or golden young twigs, each elegantly twisted into the shape of a loose and somewhat idiosyncratic corkscrew. Look for Salix 'Golden Curls' for golden stems, 'Scarlet Curls' for bicolored gold and scarlet stems, and 'Snake' for nearly black, and wavy rather than tightly curled stems. Since all will mature to very large trees where the curled and colored new growth is carried high up in the canopy, all are at their most visually effective when coppiced to keep the stems closer to eye level.

Betula Nigra Cully
Betula Nigra Cully Trees that display attractively patterned or interestingly textured bark are welcome additions to the winter landscape. For gardeners with plenty of room, our native river birch (Betula nigra) is a lovely, gracefully branched tree whose tan-and-black bark exfoliates, or peels away from the trunk. 'Heritage', sometimes sold under the name 'Cully', is one cultivar selected specifically for its highly ornamental cream-and-buff bark. Papery strips peel away from the trunk as it increases in girth, revealing varying shades of amber, pink, and cream beneath. 'Heritage', which can reach 50 to 60 feet in height, tolerates dry soils, and is resistant to the bronze birch borer that can disfigure or kill many of the white barked birch species. If you choose to plant 'Heritage' for its winter interest, look for a multi-stemmed specimen with three to four trunks to provide more bark as well as an attractive winter silhouette. If your garden cannot accommodate such a large tree, look for 'Little King', also sold as 'Fox Valley', a dwarf form with similarly ornamental bark that reaches only eight to ten feet in height.

Acer Griseum
Acer Griseum The paperbark maple (Acer griseum) is without a doubt the jewel of the winter landscape. A small, relatively slow-growing tree, it has remained both costly and scarce in the nursery trade because it is difficult to propagate from seed. Since a high percentage of the seed set by mature trees is not viable, germination is very poor. Acer griseum is a regal tree in any season, producing attractive dark green leaves that transform to a brilliant purple-red in fall, all displayed against burnished, exfoliating cinnamon-brown bark. Reaching only 20 to 30 feet in height, paperbark maple is an ideal specimen tree for a small garden. Shelter it from the high heat of midsummer by siting it in a cool, slightly shaded location.

Several selections have recently been made from crosses of Acer griseum and Acer maximowiczianum--formerly the Nikko maple (Acer nikoense). Two that are currently available are 'Girard's Form', and 'Gingerbread'. These offer Acer griseum's attractive, burnished copper bark on a more vigorous and heat tolerant tree. Three- flower maple (Acer triflorum) is another small Asian maple that makes an exquisite specimen tree. Similar to paperbark maple, its exfoliating bark peels away in a different pattern. Paperbark maple bark peels away in tissue-thin, irregularly-shaped sheets, while three-flower maple sheds its bark in cinnamon-stick curls. Small statured and round-headed, with three-parted leaves that assume reddish-orange tints in autumn, three-flower maple should ideally be placed where the delicate bark pattern can be seen close at hand.

Jap Stewartia
Jap Stewartia A number of other trees display bark with a checkered cream, buff, and gray pattern, as small plates of older bark drop away from the expanding trunk. Japanese stewartia (Stewartia pseudocamellia), an exceptionally ornamental small tree that develops outstanding bark patterns with age, is one of the best in this category. Its single white camellia-like flowers blossom in midsummer. These are soon followed by interesting beaked fruit capsules, and eventually by rich purple autumn leaves. Since Stewartia is on the borderline of winter hardiness in the Ithaca area, it should be sited in a protected location with good soil and not permitted to dry out. Like many trees that provide attractively patterned exfoliating bark, Stewartia takes many years to develop this characteristic. The bark on young trees is an undistinguished dirty gray that shows little indication of its future varied patterns of amber, cinnamon, and cream. Visit the Deans Garden on the Cornell Campus behind Warren Hall this winter to see a stunning Stewartia at its best.