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Expanding the tree palette BY ELIZABETH PETERSEN Lagerstroemia fauriei ‘Fantasy’ Larix kaempferi Pseudolarix amabilis PHOTO COURTESY OF WWW.JOHNSON-NURSERY.COM PHOTO COURTESY OF WHATSINBLOOM.WORDPRESS.COM PHOTO COURTESY OF WIKIPEDIA ™ Cryptomeria japonica Lemony Lace ‘Rein’s Dense Jade’ Oxydendrum arboreum Davidia involucrata Sambucus PHOTO BY MEGAN HANSEN PHOTO COURTESY OF PORTLANDTREETOUR.WORDPRESS.COM PHOTO COURTESY OF THE NATIONAL EDUCATION NETWORK RIED-AND-TRUE TREES it is important not to overplant any one experts are ready to suggest great trees that punctuate the skies above cities and type of tree.” deserve wider use. A new elderberry with bright golden foliage! Add some fl are suburbs, lining streets and casting In Portland, for instance, maple trees Hoyt Arboretum, which houses large 100c / 0m / 81y / 66k Tshade. But, too much of a good thing can make up nearly 30 percent of the city’s tree collections of trees and shrubs, including to the landscape with this colorful, shaggy compact mound of cause problems. When there’s too many of canopy. Instead of planting more of the some 1,300 species or cultivars of trees, is gold threads with extremely fi ne texture. White spring fl owers Contact Jeff Pipp, West Coast Account 45c / 15m / 90y / 20 just one tree variety planted, disease and/or same, designers and property owners have a great local resource. Trees from a variety produce red fruit in fall for added interest in the landscape. Representative 616-223-3361 insects can find a way to wreak havoc on an opportunity to consider other options. of native ranges are tested there to establish whole groves. But without a history of reliability in a how appropriate they are for use in the www.springmeadownursery.com “We need a diverse, resilient urban region, it can be challenging to choose from Pacific Northwest. 800-633-8859 forest,” said Martin Nicholson, curator of lesser-known tree options. Of course, just knowing about a great Hoyt Arboretum in Portland, Oregon. “So Knowledge is power, though, and tree tree is not enough; trees also have to DIGGERMAGAZINE.COM AUGUST 2016 13 SMN_July-Digger_LemonyLace.indd 1 5/27/16 1:03 PM Expanding the tree palette be available on the market, so the industry tree thrives in its current location, and it Stewartia monadelpha also needs to keep seeking new options and PHOTO COURTESY OF UNIVERSITY OF WASHINGTON is “variably evergreen,” Nicholson said, to push the envelope for what can perform BOTANIC GARDENS meaning it loses leaves during the course of well in the area. the year and produces some litter. Growing to about 30 feet tall in 20 The curator years, the southwestern native boasts As Hoyt’s curator since 2008, attractive, leathery foliage. Its narrow, dark Nicholson has watched trees weather green leaves are contrasted by dramatic seasonal extremes and has identified some white undersides. trees that offer hardiness as well as well- Nicholson credits Sean Hogan of needed diversity. Cistus Nursery with including the silverleaf One such tree is the silverleaf oak oak in the design at Hoyt, and Cistus is (Quercus hypoleucoides), which has been among the few Oregon nurseries that offer tested by 20 years of cold, harsh, rainy it for sale. winters and hot, dry summers growing in Another tree that boasts great front of the Visitor Center at Hoyt. In early character, Maytenus boaria, is commonly June, beautiful new growth on the tree grown as a California street tree, attracted the attention of visitors, few of Nicholson said. The evergreen tree reaches whom knew the tree. “It doesn’t look like 20–30 feet tall, with upright branches an oak tree,” Nicholson said. Even many and small, bright green leaves. It has been arborists don’t recognize it as such. found to be more tolerant of cold than The tough, resilient, drought-tolerant originally thought, so Hoyt has been sending cuttings to growers to trial. With the tag of “Hoyt Hardy” to identify the source of the cuttings, the Available in 3 Convenient Sizes: cold-hardy tree may prove to be an appropriate choice outside its native range 4 oz of South America. ® Pint Wood’s Even though Stewartia pseudocamellia Rooting Compound Gallon is popular and available, other varieties in the genus have great characteristics that deserve wider use, Nicholson said. S. monadelpha has a tall form with great growth and eye-catching, bright orange bark. S. rostrata grows more slowly into a beautiful, rounded smaller tree with white flowers. Davidia involucrata performs well The Professional’s Choice as a yard tree, but it doesn’t like the heat of the street, Nicholson said. Known as Soluble, self-sanitizing, concentrated rooting formula promotes the “dove tree” or “handkerchief tree,” instantaneous absorption of NAA & IBA. Flexible dilution ratios Davidia is part of the dogwood family according to your plant propagation needs. EPA approved! and blooms from April to May with breathtaking inflorescences, each composed of a small reddish flower and long, pure Call Today For Ordering Information: (503) 678-1216 white bracts, which are said to resemble dangling handkerchiefs or doves resting on the branches. The World Leader in Ion Exchange Technology ‘Tricolor’ has “really remarkable P.O. Box 327, Wilsonville, OR 97070 variegation,” Nicholson said. He also said visitors to the arboretum are fascinated by www.earthscienceproducts.com the cultivar ‘Sonoma’, which has bracts that are more than twice the normal size. 14 AUGUST 2016 DIGGERMAGAZINE.COM Premier Supplier of Nursery Products • Shipping Materials - Stickers, shelves and pallets made to your specs, pallet repair boards, shipping gates, tilt sticks, used pallets • Packing Supplies - Shrink wrap, banding • Planting Stakes Birch trees that resist the bronze - Multiple sizes available birch borer also deserve increased use, • Treated Lumber and Nicholson’s favorite is a Japanese - Multiple sizes available native — the monarch birch (Betula maximowicziana). Not only does it have 503-434-5525 good resistance to borers, it also has great 1726 SW Highway 18, McMinnville, OR 97218 • www.dstakemill.com 6152 form and striking, 6-inch catkins. For outstanding fall color, Nicholson recommended Larix kaempferi, the Japanese larch. Smaller than the Western larch, this deciduous conifer is very cold hardy; bright green needles turn a remarkable yellow and orange in fall. Pseudolarix amabilis, known as the golden larch, also produces great fall color and should be used more, Nicholson said. Although also a deciduous conifer, it is not a true larch. Still, the beautiful tree likes full sun and heat, making it a good choice for a wide swath of the country, including the southeastern U.S. The breeder/researcher Ryan Contreras of Oregon State University’s Department of Horticulture is an ornamental plant breeder and researcher. His goal is to develop plants that are well suited for production and that meet the needs of gardeners. He offered several recommendations for undeservedly underused trees. Selections of Cryptomeria japonica, the Japanese cedar, are available in many sizes and shapes to fit virtually every landscape need, he said. From little round balls to fastigiate forms and unusual foliage, these versatile dwarf conifers have great potential. Contreras recommended the narrowly upright C. japonica ‘Rein’s Dense Jade’ for its formal appearance, dense growth and superior branching. Its foliage provides added interest, taking on bronzy purple tones in winter. As a big fan of tree lilacs, Contreras recommends Syringa reticulata. Few issues affect the trees, which grow 20–30 feet tall. Unlike shrub lilacs, the tree blooms at a different time, producing large clusters of small, creamy white flowers from late spring to early summer — their fragrance is “amazing,” Contreras said. Beautiful reddish-brown bark that resembles DIGGERMAGAZINE.COM AUGUST 2016 15 Expanding the tree palette cherry trees adds to the appeal. in sheets and reveals smooth orange, white Contreras spoke well of another and pale reddish-brown bark. bronze birch borer-resistant species, Betula ‘Fantasy’ grows much larger than nigra. Good resistance and attractive the common crape myrtle (L. indica), exfoliating bark make it superior to has golden fall color and boasts strong species like B. pendula and B. utilis var. resistance to powdery mildew. jacquemontii, both of which are susceptible Contreras credited Paul Bonine, owner to the pest. of wholesale specialty plant nursery Xera Finally, tree-form crape myrtles do well Plants in Sherwood, Oregon, with boosting in the Pacific Northwest and deserve greater the availability of proven crape myrtle use, Contreras stated. Many choices, cultivars in the Pacific Northwest. Xera especially among the Lagerstroemia fauriei Plants offers varieties specifically grown types and hybrids, offer an assortment of and tested for their propensity to bloom in sizes and shapes for a variety of situations. local summers that are cooler than those in One of his favorites is ‘Fantasy’ for southern states. its attractive cinnamon, exfoliating bark. Discovered at the JC Raulston Arboretum The arborist in North Carolina, it is one of five L. Kevin Carr, certified arborist with fauriei seedlings grown from seed collected Collier Arbor Care, a division of Bartlett in Japan. White flowers appear in June, Tree Experts in Clackamas, Oregon, shared but in mid-summer, the bark show kicks Nyssa sylvatica his thoughts on lesser-used options for PHOTO BY JEAN-POL GRANDMONT in as rich cinnamon-brown bark exfoliates choice trees. 16 AUGUST 2016 DIGGERMAGAZINE.COM • Potting machines • Robot systems • Tray automation • Substrate handling • Transport systems As an arborist who deals with tree issues day in and day out, Carr promotes trees that require limited input for optimal plant health, especially ones that are not 770-428-4491 impacted by pests and other problems. [email protected] He agreed that crape myrtles are a www.javousa.net great choice for hot, full-sun conditions.