Archive for Saturday, November 11, 2017

Garden Variety: Uncommon trees add subtle color to winter garden

November 11, 2017

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When selecting plants to add winter interest in the garden, consider using trees and shrubs with interesting bark and/or branches to add subtle color and texture. Lacebark elm and river birch are probably the most common additions, with peeling, highly-textured bark, and red-twig dogwoods get all the credit for branch color. For more unusual options, consider paperbark maple, Persian ironwood, seven-son flower, contorted filbert, or Twisty Baby locust.

Paperbark maple (Acer griseum) is a 20- to 30-foot single-stemmed tree with peeling bark. The tree is well-suited to the Midwest except for being intolerant of drought, so supplemental irrigation or willingness to water is a must. The bark peels in thin sheets, revealing a range of brown, gray, orange and cinnamon colors. Paperbark maple is less common and more expensive than other maples in the nursery industry because it is difficult to propagate.

Persian ironwood, Persian parrotia, or (Parrotia persica) is another somewhat uncommon tree with interesting bark that is underutilized in the Midwest. Its bark exfoliates but is mostly smooth with shades of pale green to gray somewhat similar to the bark of a sycamore. Persian ironwood can reach 20 to 40 feet tall, but is more commonly found in the 10- to 15-foot range. It can be a single-stemmed tree or multi-stemmed shrub.

Seven-son flower (Heptacodium miconioides) is a 15- to 20-foot shrub that may be pruned to maintain a smaller size. It has gained some popularity in recent years for its attractive flowers and foliage as well as its bark. The bark is tan and semi-smooth. It peels in long strands, leaving a sort of fringe in sparse patches along the trunk and stems.

Contorted filbert or Harry Lauder’s walking stick (Corylus avellana ‘Contorta’) has been around since the mid-1800s but has limited use in the landscape because of its shape and growth habits. In the right site it is a beautiful, extremely interesting specimen planting. The stems of this plant are wildly twisted, curling back and forth into each other. In spring and summer, large, rough green leaves take a bit of beauty away from this plant as they cover many of the curls. Winter is truly the season to enjoy contorted filbert. Contorted filbert reportedly grows to 8 to 10 feet tall but is typically smaller.

If adding contorted filbert to the garden, take care to try to find a non-grafted plant. Grafting is common with many tree species in the nursery industry to get a finished product more quickly. In this case, if contorted filbert is grafted onto a non-contorted rootstock, the roots will likely sucker. Suckers will have to be pruned out annually or semi-annually to maintain the shape of the plant. Nongrafted plants may still sucker, but suckers will be contorted like the parent plant so can be left unless size becomes an issue.

Twisty Baby locust (Robinia psuedoacacia ‘Lace Lady’) is a specific variety of black locust that was selected for its twisted, zigzagging branches. It is much less twisty than contorted filbert but still interesting. Twisty Baby reportedly grows to 8 to 10 feet tall and can be found as a single-stemmed tree, a multi-stemmed shrub, or a top-grafted tree (where the tree is grafted onto a 6-foot-tall single stem).

Twisty Baby is the trademarked name for the cultivar Lace Lady, which was patented in 1996.

Although black locust is native to the region, it has a few insect pests that can stress the tree and shorten its life. It also produces spines although they are less common on Twisty Baby than on the species. The spines are similar to rose thorns and are much less obnoxious than those of the unrelated honeylocust tree. Twisty Baby also rarely flowers, which may be disappointing to some, but the lack of flowers means that the plant rarely produces seed pods.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.

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