ARBORETUM BULLETIN Published by The Arboretum Foundation for the University of Washington IN THE LANDSCAPE * m Jr i S - r w Br, Officers of The Arboretum Foundation Duane Kelly, President Vice Presidents: Sheila Taft, Administration Margaret Li, Unit Council Joanne White, Special Events Phil Wood, Arboretum Planning Gail Donahue, Secretary Steve Garber, Treasurer Mary Thorne, Immediate Past President Jan Patrick, Immediate Past Unit Council Chair Debra Holland, Executive Director Jan Silver, Editor, Arboretum Bulletin Elliott Bronstein, Editor, Newsletter Regen Dennis, Public Relations Cindy Jackson, Administrative Assistant Pamela Tharl, Bookkeeper Editorial Board of the Arboretum Bulletin Jan M. Silver, Editor and Designer Tom Berger Linda Brubaker, Ph.D. Valerie Easton, Book Review Editor Daniel J. Hinkley Jon Hooper Arthur R. Kruckeberg, Ph.D. Steven R. Lorton, Advisor Bill Mackay, Arboretum Foundation Liaison Susie Marglin, Advertising Director Brian O. Mulligan Sue Maloney Nicol Jan Pirzio-Biroli University of Washington WASHINGTON PARK ARBORETUM John A. Wott, Ph.D., Director of Arboreta Brian O. Mulligan, Director Emeritus Curatorial/Management Staff: Tracy Omar, Assistant Curator and Recorder Christina Pfeiffer, Horticulturist Barbara Selemon, Propagator CENTER FOR URBAN HORTICULTURE Clement W. Hamilton, Ph.D., Director ADVERTISERS Please call Susie Marglin, Advertising Director, (206) 325-4510. Concerning this issue... If asked to name a common tree, many would say “maple.” Surprisingly, however, few publications are devoted to this glorious genus, which has so much more diversity of leaf form, color, and bark than die maple whose leaves we pressed between waxed paper as school- children. Considering that the Washington Park Arboretum has one of the leading maple collections in North America, it seemed natural to prepare this special issue when it was suggested by editorial board member Jan Pirzio-Biroli. We know that these articles, which represent just some of the wonders of maples, will get you interested in further exploring their uses in your garden landscape. Within this publication, Arthur Lee Jacobson, author of Trees of Seattle , presents some notable Seattle maples. Brian Mulligan, director emeritus of the Washington Park Arboretum, has prepared a tour of some Arboretum highlights. Mr. Mulligan also writes about our special Japanese maple collection, and Chris Pfeiffer, Arboretum horticulturist, explains how to prune one. Unusual leaves and colors await us among three maples that nurseryman Daniel Hinkley covers in his article. For those who are only aware of two of the Northwest’s native maples — big-leaf and vine — Mary Sue Gee explains where to see Douglas maple and how to use it in the land- scape. For those of us who have maples but just need to know how to diagnose problems that may arise, Washington State University Cooperative Extension authors Carrie R. Foss and Ralph S. Byther explain what to do. For other publications on maples, see Valerie Easton’s column, and for an overview of the Japanese maple collection and an update on the Arboretum, see Director John A. Wott’s quarterly remarks. Welcome to the editorial board’s new liaison with The Arboretum Foundation, Bill Mackay, who has previously served as Foundation treasurer. A treasure to work with, Bill is a long-time Arboretum Foundation member, and we are very grateful for his ongoing contribu- tion to the Bulletin’s success. It takes people like Bill to develop and enhance a living museum such as the Washington Park Arboretum. Jan Silver, Editor The Washington Park Arboretum Bulletin cover: Appearing to have the first blush of autumn color are the variegated leaves of Acer palmatum ‘Karasugawa’ in May, in the Washington Park Arboretum Japanese maple collection. Find this specimen on grid number 32- IE on an Arboretum map. Photo by Joy Spurr. CONTENTS Volume 57:3 Features Seattle’s Common and Rising Star Maples, and the Devil Withal by Arthur Lee Jacobson 2 Japanese Maples of the Washington Park Arboretum by Brian O. Mulligan 6 A Tour of Arboretum Maples by Brian O. Mulligan 10 Diagnosing Maple Problems by Carrie R. Foss and Ralph S. Byther .... 12 Underused Understory: Three Maples for the Pacific Northwest by Daniel J. Hinkley 16 Pruning Japanese Maples by Christina Pfeiffer 20 The Capricious Native: Acerglabrum ssp. douglasii by Mary Sue Gee 22 Columns In the Washington Park Arboretum by John A. Wott 26 Book Review Maples of the World reviewed by Daniel J. Hinkley 29 For Further Information: Maples by Valerie Easton 30 New on the Shelves of the Elisabeth C. Miller Library by Valerie Easton 31 Note 32 To find which plants in this issue can be viewed in the Washington Park Arboretum, see the newly revised The Woody Plant Collection in the Washington Park Arboretum , available in the Graham Visitors Center gift shop. The Washington Park Arboretum Bulletin is published quarterly as a bonus of membership in The Arboretum Founda- tion, Seattle, Washington. The Arboretum Foundation is a non-profit organization that was chartered to further the development of the Washington Park Arboretum, its projects and programs, by means of volunteer service and fund raising. The Arboretum is administered through cooperative efforts between the University of Washington, its Center for Urban Florticulture (CUH), and the City ofSeatde Department of Parks and Recreation. The programs and plant collections are a responsibility of CUFI. The mission of The Arboretum Foundation is to ensure stewardship for the Washington Park Arboretum, a Pacific Northwest treasure, and to provide horticultural leadership for the region. This stewardship requires effective leadership, stable funding, and broad public support. Articles on gardening and horticulturally related subjects are welcome. Please call the Bulletin editor for guidelines or permission to reprint. © 1994 The Arboretum Foundation. ISSN 1046-8749. Information ARBORETUM: Visitor services, programs, and collections; (206) 543-8800. CUH: Public education programs and the Elisabeth C. Miller Horticultural Library; (206) 543-8616, 685-8033. THE ARBORETUM FOUNDATION: Become a member and receive four issues of the Bulletin , 11 issues of the newsletter, plant sale catalogs, discounts, and early notice of programs and special events. Send membership payment to The Arboretum Foundation, University of Washington XD-10, Seattle, WA 98195; (206) 325-4510. Individuals, $25; Families, businesses, and organizations, $35; Sustaining, $50; Contributing, $100; Supporting, $150; Sponsor, $200; Lifetime membership, $1,000. Printed on 50% recycled gloss coated paper (10 percent post-consumer waste) Design and production by Barbara Rowan Graphic Design top: Acer saccharum (sugar maple), in fall top inset: Acer platanoides ‘Emerald Queen’ (Norway maple) by die Seatde Public Library bottom: Acer macrophyllum at University of Washington 2 Washington Park Arboretum Bulletin Seattle’s Common and Rising Star Maples, and the Devil Withal photos and text by Arthur Lee Jacobson ny account of Seattle maples must give first place to what is surely the city’s most common tree, bigleaf maple (Acer mctcrophyllum) . Outstanding for abundance, large size, and immense leaves golden in fall, it is very familiar. However, its presence is waning yearly. At the turn of the century it was our most planted street tree. Now, the majority of such specimens have died or are rotting, and for many years it has been illegal to plant bigleaf maple as a street tree because its roots so readily buckle concrete. Also, insect or disease attacks are more prevalent than in earlier decades. Currently, in Seattle’s woodland parks, Nor- way maple and sycamore maple are colonizing faster than the bigleaf, because they reproduce easily in shade. This scenario means bigleaf maple is, as a group, past its prime in the arbo- real drama of Seattle’s lifespan. As the specimens in the Washington Park Arboretum decline and are removed, the result will be an improvement, overall, but not without the price of some costly removal work and sunburned rhododendrons. Many Seattleites are of Norwegian back- ground. Norway maple (Acer platanoides) seems poised to take the lead as Seattle’s premier maple in the future. Though native-plant lovers may sigh, nature’s bottom line is survival of the fittest. Norway maple’s toughness, crisply hand- some looks, and weedy reproductiveness all bode well for it. If money did grow on trees, inves- tors would do well to swell their portfolios with stock of this naturalized foreigner. Nearly 50 Norway maple cultivars have been grown in North America whereas bigleaf maple has none Vol. 57:3 Fall 1994 left: Acer palmatum ‘Sango Kaku’ (coralbark maple) right: Acer jap onicum ‘Aconitifolium’ (fernleaf maple) 3 to speak of. The Norwegian can be bought in a wide variety of forms, colors, and sizes. Every nursery sells them. Although we respect strength in a tree since power compels attention, we really thirst for beauty. However elegant their branching, maples are preeminently associated with lovely fall color. Neither bigleaf maple nor Norway maple are better than average in this attribute. Both are usually pleasant enough but not consistently spectacular. For the best Northwest display of brilliant orange among the large -growing spe- cies, there is no rival to the eastern American sugar maple (Acer saccharum). Seattle’s dry summers and sterile gravelly soils are perfect for stressing this species, thereby, as it were, inflam- ing its passion and causing it to blush sooner and redder. Seattle’s largest sugar maple, 90 feet tall and 72 feet wide, is a street tree on Capitol Hill, on 17th Avenue East, just south of East Roy Street. If pure red is preferred, the best large shade tree maple is another denizen of eastern United States woodlands, red maple (Acer rubrum). Unlike sugar maple, this has been overplanted here, at least during the last 20 years. Its perfor- mance has not been without blemish; neither it nor sugar maple are the slightest bit inclined to run wild. Although not known for fall color, phenomenal rapidity of growth characterizes silver maple (A. saccharinum), which also hails from the eastern United States and similarly loathes our dry summers too fiercely to natu- ralize here. Some promising hybrids between red maple and silver maple are now available; these are selections of A. xfreemanii. Do you desire lively red from a smaller-scale maple? If so, the ideal trees are Japanese maples (Acer palmatum) in cultivars such as ‘Osakazuki’ or ‘Tobiosho’. Another relative from Japan with equally stunning red fall color is the fernleaf maple (A. japonicum ‘Aconitifolium’). A few Japanese maples are at their best in spring, with the young emerging foliage look- ing all the world like fiery red fall color in April. These cultivars include ‘Chishio’, ‘Corallinum’, ‘Deshojo’, ‘Seigai’, and ‘Shindeshojo’. The most overrated imposition of mapledom in recent years is the coralbark Japanese maple (Acer palmatum ‘Sango Kaku’). Its leaf is small, conventional, and seems to scorn flamboyant fall color as unworthy of its attention so settles for an undistinguished yellow. When it is na- ked, however, it shines — scintillating bright red stems that really warm the spirit in winter. The problem with coralbark maple is that it is too brief in its glory. As a fast- growing youthful shrub or small tree it draws admiration from all. But give it 10 or 20 years, and bit by bit it de- generates into nondescript background, while other maples are growing more stately and no less beautiful with age. An improved version of coralbark maple called ‘Beni Kawa’ is worth trial, however. Even if it proves to be only a brief fling, it ought to be great fun while it lasts. The maple with the most fascinating name happens to be one of the dullest imaginable in leaf and form and would be utterly condemned 4 Washington Park Arboretum Bulletin if it did not have intriguing flowers and its catchy name, devil maple (Acer diabolicum). Yes, this is one of those plants gardeners want to grow, or at least know, simply for the name. It is from Japan, where the name “onimomiji” means dev- ilish. It was so called because of the “wild and violent appearance of the leaves.” Westerners, unaware of the reasons behind the name diabolicum , imagined it was derived from the stinging brisdes on the seeds and/or the two tiny styles (like devil’s horns) on them. Because Acer diabolicum is so slow and dull, it is exceedingly rare. Do not despair. On the lawn west of the Japanese Garden parking lot, you can see two devil maples near the 3 5 -foot- wide hornbeam maple (A. carpinifolium). The southernmost devil maple is male, the north- ern one female. In spring, the female flowers up close are joyously fascinating salmon-pink. But they result in seeds that look like unsightly clusters of waste paper among heavy foliage on a clumsily stout trunk; the entire tree is abso- lutely graceless, its fall color tawny (or, rarely, a good yellow). Arthur Lee Jacobson is the author of Trees of Seattle, Trees of Green Lake , and Purpleleaf Plums. Acer saccharum m* Garden Carpentry ^ Free Custom Design 't’ Tandaker CONSTRUCTION 632-5583 Licensed and Bonded • #LANDAC*181ML (Located 7 V2 miles from any ferry) 20211 Vashon Hwy. S.W., Vashon Island, WA 98070 206-463-3655 (Seattle) An uncommon place at the heart of Vashon Island. Offering the unusual in perennial ornamentals, herbs, garden decor, gifts, natural fiber clothing and more. Send $1.00 for plant list. Vol. 57:3 Fall 1994 5 PHOTOS ON THIS PAGE BY JOY SPURR * 0*0* i. -'A v,\ v x , * ;■ ■ - W i V V- A." ■iiv- -4k L ■ j * rN W ' r ’ w 4 . ~v ^ •> ^ • * - V-*^ »fe. ffe - *# * .. » ? ► •— ' ■ ■ - jk ■ a. - V Mfci't 1 top left: Magenta samara (seed) among spring foliage of Acer palmatum ‘Shikageori Nishiki’ in the Arboretum top right upper: Spring foliage of Acer palmatum ‘Nomura’ top right lower: Acer palmatum ‘Nuresagi’ in May bottom: Acer palmatum var. dissectum ‘Viridis’ in the Arboretum in July opposite: The Arboretum’s specimen of Acer palmatum ‘Osakazuki’ will mature like this one from VanDusen Garden. 6 Washington Park Arboretum Bulletin Japanese Maples of the Washington Park Arboretum by Brian O. Mulligan China, with its huge land area, contains by far the largest number of species of maples (Acer) of any country in the world. In contrast, North America boasts 13 (Sargent 1965). Fora comparatively small country in land area, how- ever, Japan is home to 22 species of maples. When the term Japanese maple is mentioned, most gardeners and plants people think at once of some form of Acer palmatum. It is with these that this article is chiefly concerned, since it has given rise over the course of centuries in Japan to so many different variations and forms, both Vol. 57:3 Fall 1994 7 ARTHUR LEE JACOBSON V Acer palmatum ‘Omato’ in growth habit and leaf shape and coloring. Acer palmatum in the Arboretum Two succcessive large importations of plants were made in March 1940 and March 1941, from the nursery of K. Wada in Japan. These were chiefly forms of Acer palmatum but also included plants of a few other native species and some magnolias. This was a very fortunate purchase at that date, as subsequent events proved. Dr. John Hanley was director of the Arboretum at that time and probably respon- sible for it. The 1940 consignment included 82 clones of Acer palmatum , with several each of A. japonicum and A. sieboldianum — over 300 plants in all. In 1941, 71 plants were received, representing 43 clones of A. palmatum , distinct from the 1940 lot. At this point, there were 125 clones of this species in the Arboretum. In January 1958, nine plants came from the nursery of H. J. Hohman, Kingsville, Maryland, a well-known nurseryman of that era. Eight of these were forms of Acer palmatum , one of A. japonicum. Then, in November 1966, a ma- jor collection, 79 plants in all, was given to the Arboretum by Mr. Rod Searles of Indianapolis, Indiana, who learned that he could not grow them outdoors in that climate. Most of these plants had previously been imported by him from Japan; a few had come from the Nether- lands or the Hohman nursery in Maryland. The Searles accessions varied greatly in size, from nine to 12 inches to some 3.5 feet tall — usually only one plant of each kind. Five clones were of A. japonicum , one the very attractive form of A. cratae£jifolium with variegated foliage, named ‘Beni uri’. The Wada Japanese maples spent the World War II years (1941-1946) in the old nursery on the slope just south of the lath house. By the end of 1946 or early 1947, when I inventoried them, many were from three to six feet in height and urgently needed moving out, like most other plants there. Plantings The area allotted to the maple family under the Olmsted plan was on the west side of Lake Washington Boulevard East between the Madi- son Street playfield and Interlaken Boulevard, where the Japanese garden now flourishes. From 1945 to 1946, a few plants were placed there and still remain within the garden, mostly near the south end and the small stone bridge. Many more of the Wada plants were moved in April 1948, totalling 51 different clones. The first to the Woodland Garden were in April and May 1949. Some of those in the original site were transplanted to the Woodland Garden or just north of it in December 1955, some a year later, and others in January 1958. The first plantings of the Searles maples were in the spring of 1968, into or around the Wood- land Garden. Others followed in January and December 1971, as they became large enough to move. Two, ‘Beni Kagami’ and ‘Samidare’, went to the Japanese Garden in April 1971. Also in 1971, former Arboretum curator Joseph Witt was responsible for the group plant- ing at the southeast corner of the Woodland Garden, close to Arboretum Drive East, and ad- ditions were made in the spring of 1973. And Acer palmatum ‘Butterfly’ 8 Washington Park Arboretum Bulletin Joe made two more quite extensive plantings of Searles maples, one in the spring of 1977 (15) on the south bank of the Woodland Garden near its west end, the other ( 1 1 ) on the north bank in December 1978. A review of all the Japanese maples made this summer by student intern Kim Anderson shows that 68 accessions are correcdy named and iden- tified. Four of these are only found in the Japa- nese Garden. Thirty- eight are represented by only one plant, a regrettable state that should be rectified systematically as soon as possible. Eleven clones need further checking either in spring or fall to confirm their identities. Of Japan’s 22 maple species, only one, Acer tenuifolium , a near relative of both A. palmatum and A. shimsawanum , is not found in the Wash- ington Park Arboretum. It is, however, described and illustrated in the magnificent book of the late J. D. Vertrees , Japanese Maples, so it should not be too difficult to add a plant or two to our collections. Recommended Clones of Acer palmatum (* = in WPA) SPRING OR SUMMER FOLIAGE COLOR *‘Atropurpureum Superbum’, *‘Bloodgood’, *‘Mushashino’ (‘Nomura’), *‘Nuresagi’, ‘Trompenburg’, *‘Tsuma Beni’ VARIEGATED LEAVES * ‘Butterfly’, *‘Higasayama’, *‘Karasugawa’, *‘Orido Nishiki’ PENDULOUS HABIT, LARGE PLANTS *‘Burgundy Lace’, ‘Kinran’, *‘Matsukaza’, *‘Ogonsarasa’, *‘Omurayama’ DISSECTUM FORMS ‘Garnet’, *‘Ornatum’, ‘Sunset,’ *‘Viridis’ FALL LEAF COLOR (RED OR YELLOW) *‘Omato’, *‘Ozakazuki’, *‘Tana,’ *‘Hagoromo’, *‘Tsukushigata’, *‘Ukon’, *‘Yezo Nishiki’ Brian O. Mulligan is director emeritus of the Wash- ington Park Arboretum and a lifetime member of the editorial board of the Washington Park Arboretum Bulletin. References Ohwi, J. 1965. Flora of Japan (in English). Washington, DC: Smithsonian Institute. Sargent, C. S. 1965. Manual of the Trees of North America. New York, NY: Dover Publications. Vertrees, J. D. 1978. Japanese Maples. 2 ed. 1987. Portland, OR: Timber Press. The Berger Partnership, P.S. 2021 Minor East Seattle, Washington 98102 (206) 325-6877 Landscape Architecture Site Planning Olympic CoAtt Grtdch Many named varieties of Kniphofia, also a wide selection of other field grown perennials shipped. Descriptive catalog $1. 84 Eaton Lane Sequim, WA 98382 Vol. 57:3 Fall 1994 9 top left upper: Acer grosseri (stripebark maple) bark top left lower: Acer griseum (paperbark maple) bark top right: Acer rubrum ‘October Glory’ bottom: May flowers of Acer circinatum (vine maple) 10 Washington Park Arboretum Bulletin JOY SPURR A Tour of Arboretum Maples by Brian O. Mulligan color photos by Joy Spurr Starting at Graham Visitors Center, you ean view notable specimens of Acer (maples) during a loop walk through the Washington Park Arboretum. 1. Acer eircinatum , native vine maple, opposite Graham Visitors Center. 2 . Acer eapillipes , in the Woodland Garden, which also has many forms of A. palmatum. 3. Acer japonicum and A. sieboldianum , at southeast corner of the Woodland Garden. 4. Acer grosseri in collection of Asiatic maples, with A. davidii. 5. Acer griseum , with Asiatic maples. 6. Acer tegmentosum , in peony collection, by Arboretum Drive East. 7. Acer davidii , a large specimen. 8. Acer saeeharum ‘Globosum’, a round- headed form of the American sugar maple, coloring orange in October. 9. Acer macrophyllum ‘Seattle Sentinel’, a fasti giate form of our native species. 10. Acer rubrum , the red maple, in several different forms here; colors well in fall and is visible from Lake Washington Boulevard East and Azalea Way. Brian O. Mulligan is director emeritus of the Washington Park Arboretum. One of the unusual species of stripebark maples in the Arboretum, Acer tegmentosum. Vol. 57:3 Fall 1994 11 BRIAN O. MULLIGAN Diagnosing Maple Problems by Carrie R. Foss and Ralph S. Byther any problems of maple trees have similar symptoms at first glance. Deter- mining whether the tree has Verticillium wilt, Nectria canker, leaf scorch, or anthracnose re- quires thorough examination of the tree and knowledge of the potential problems. To aid in using the diagnostic methods suggested below, carry a sharp knife and hand lens (or dissecting microscope), and have good reference materi- als at hand to supplement this article. To Start the Diagnosis The first step in diagnosing your maple’s prob- lem is to clearly note all the symptoms and their distribution on the tree. Look at leaf symptoms for the first clue in determining the type of disease involved. Leaf spots or blotches ran- domly distributed on the leaf indicate a foliar disease problem. Marginal leaf necrosis — dead areas confined to leaf margins — is often related to a cultural or environmental problem. To help diagnose the problem, note the dis- tribution of leaf symptoms on the entire tree; for example, a root rot problem usually affects the entire tree, while a canker disease may affect only one or two branches. Though leaf symptoms are important, also determine if the twigs and branches are alive or dead. A green layer beneath the bark indicates that the tissue is alive; if it is brown or black, it is dead. Examine twigs, main branches, and the trunk at the soil line. It may also be necessary to check the roots. The next step in diagnosis is to carefully examine the affected plant material with a hand lens or dissecting microscope. “Signs” of a fungus, such as thread-like hyphae or fungal fruiting bodies, may reveal the specific organ- ism causing the problem. Insect cast skins, frass (insect excrement), or presence of insects may be clues to an insect-related problem. Also useful in problem solving is finding information about the history and cultural practices surrounding the tree. Note the plant size. Also obtain information on watering practices, fertilization, and chemical usage. Determine when the tree was planted and when the problem was first observed. The final step includes putting together all the information you have obtained and consult- ing reference materials to diagnose some of the problems. Following this section are brief sketches of each problem; if you need further information, consult Diseases of Trees and Shrubs (Sinclair et al. 1987), which contains many photographs and biological descriptions. Exten- sion bulletins are available on the leaf scorch of shade trees, Verticillium wilt, Armillaria root rot, and Nectria canker. The Pacific Northwest Plant Disease Control Handbook (Koepsell and Pscheidt 1994) contains brief problem descriptions and explains techniques for managing disease. Verticillium Wilt Verticillium wilt, a disease of many different kinds of plants, is particularly common on maples. Where this disease occurs, the leaves on Photos top: The fungal disease, maple anthracnose, can cause foliar symptoms similar to leaf scorch, which are randomly distributed on the tree. Anthracnose lesions are often associated with veins and may be necrotic spots or irregular blotches. BOTTOM LEFT AND RIGHT UPPER! Verticillium wilt is particularly common on maples, causing leaves to suddenly wilt and die or drop. They may be stunted or yellow. Another indication is olive -green streaks when a lengthwise cut is made in the sap wood. Often initial symptoms will only occur on part of the tree, while the remainder appears healthy. bottom right lower: If your maple shows cankers, dieback, or leaf spots, it may have Pseudomonas syringae pv. syringae. 12 Washington Park Arboretum Bulletin Vol. 57:3 Fall 1994 13 PHOTOS BY RALPH S. BYTHER diseased maples may suddenly wilt and die or may suddenly drop at any time during the grow- ing season. These symptoms may occur on only one or on several branches, on only one side, or over the entire tree. The leaves may or may not be stunted to yellowed. ^Diseased maples^ may die quickly or may live for years. Younger trees usually show a greater degree of damage than older ones. To confirm the diagnosis of Verticillium wilt, cut lengthwise into the affected twigs and branches and possibly into the trunk. Look for olive-green streaks in the sapwood just below the cambium. The intensity of streaking will vary and may not be evident in all of the branches showing symptoms. Therefore, examine a num- ber of twigs and branches before making a final judgment. Symptoms are reported to be most intense in the trunk and roots but are difficult to sample on large trees in a landscape situation. The fungi causing Verticillium wilt, Verticil- lium albo-atrum and V dahliae, usually infect the plant through the roots but can also infect through wounds on the above-ground parts of the plant. The fungus can survive in the soil for many years, even after the diseased plant has been removed. Although severely infected trees usually die, Verticillium wilt can be culturally managed in some cases to prolong the life of the infected tree or perphaps aid in its recovery. First, prune out and destroy affected branches. Destroy the infected branches by burning or placing in the rubbish. Give the tree good cultural care to ensure normal growth. Avoid over- fertilizing (especially nitrogen), and keep the tree watered to avoid water stress. Completely remove dead trees, including the root system. Prevent the movement of infected soil to other areas of the landscape. Do not track it on shoes or carry it on tools. Be sure to sterilize pruning and diag- nosis tools before working on another tree. Replant with a Verticillium-rcsistznt or -im- mune tree or shrub, such as birch, dogwood, willow, or juniper. Lists of resistant plants are available in reference materials. Canker Diseases Several canker diseases can afflict maple trees. The presence of a canker may first be noticed in the spring when new leaves emerge and subse- quently die or show severe symptoms of scorch. The dearh of Laves may then be traced back to qjdead area on the trunk or branch. Identify this dead area or canker by making small cuts to examine the vascular cambium. Japanese maples are susceptible to winter injury that may result in a canker on the trunk or a main branch. When only moderately cold temperatures occur, the phloem, which is the principal food-conduct- ing tissue, may be green while the vascular cambium is discolored black or dark brown. Sometimes these branches may recover, but usually they will die. If your maple has cankers, dieback, or leaf spots, it may have Pseudomonas syringae pv. syringae. The pathogenic bacteria invade maple tissue by entering the plant through wounds or natural openings. Frost damage and heavy rains favor disease development. Cankers resulting from winter injury may subsequently become infected by P. syringae and result in a blacken- ing of the tissue. The leaf- spot phase of the disease usually begins as small water-soaked lesions with yellow halos which later blacken and coalesce to form blotches. One-year-old twig infections turn black in the dormant season. The infected twigs may produce leaves the follow- ing spring and then die back. To get rid of the bacteria, remove and de- stroy dead twigs and fallen leaves of an infected tree. Prune the tree during dry weather to provide adequate air circulation and protect from rain and frost, if possible. Severely infected trees should be removed and destroyed. Neetria or Tubereularia canker are fungal diseases of numerous tree species including maple. These fungi usually invade maple tissue through wounds and are not considered aggres- sive pathogens. Winter injury, damage from drought, sunscald, leaf scars, cracks in the twig axil, or senescent low branches predispose a maple to disease. Maples can be infected by two Neetria spe- cies, Neetria cinnabarina and N.galligena. The perfect (sexual) stages (N. cinnabarina or N. galligena) are characterized by small, globose, orange -red to dark red fruiting bodies that can be easily seen with a hand lens. The conspicu- ous imperfect (asexual) stages ( Tubereularia vulgaris or Cylindrocarpon mali , respectively) are either coral-pink to pink-orange or creamy spore masses rupturing through the diseased bark. To manage Neetria canker, prune and destroy 14 Washington Park Arboretum Bulletin infected twigs and limbs. Avoid creating wounds and branch stubs from pruning. Fertilize and water properly to keep the tree growing vigorously. However, avoid fertilizing in mid- summer to early fall to allow new growth to harden prior to cold weather. Leaf Scorch Leaf scorch describes a symptom commonly observed on maple and other shade trees. Dead leaf margins and areas between the veins are usually distributed uniformly on the tree. The tissues between the wood and the bark of twigs and branches will be alive and not discolored. There will not be dark streaking in the sapwood as observed with Verticillium wilt. Leaf scorch symptoms most often indicate that water uptake has been inhibited; there are many possible causes, both pathogenic and environ- mental. Pathogenic cankers and root rots may first become apparent when leaf scorch symptoms are observed. Over- fertilization may damage fine roots or result in translocation of excess salt to leaf margins. Drought stress, improper planting, root girdling, overwatering, and wipi-er injury m the trunk are some of the factors that can result in leaf scorch symptoms. Identifying the exact cause of leaf scorch can often be difficult, but it is the important first step in finding a possible solution. Anthracnose The fungal disease, maple anthracnose, can cause foliar symptoms similar to leaf scorch. However, anthracnose lesions are usually not restricted to marginal and interveinal leaf tissue and are randomly distributed on the tree. Anthracnose lesions are often associated with veins and may be necrotic spots or irregular blotches. Twig infections may also result in cankers that provide overwintering sites for the fungus. Severely infected trees may be prematurely defoliated. Examining lesions with a hand lens may reveal the presence of tan fruiting bodies that help diagnose Discula spp. and Kabaticlla apocrypta , which cause maple anthracnose. Manage through good sanitation practices. Rake up and destroy infected leaves. Prune out and destroy infected twigs. Highly susceptible trees may require protective fungicide applications during the spring and summer until the advent of dry weather. Leaf Spot Other maple leaf diseases include Phyllosticta leaf spot and Rhytisma tar spot. Phyllosticta leaf spot produces small, reddish brown, circular spots with purple borders on most susceptible maples. Tiny black fruiting bodies may be observed with a hand lens in the dead areas. Phyllosticta leaf spot can cause severe damage on Japanese maple where the spots appear to be tan or straw colored. Rhytisma tar spot is common on bigleaf maples and attacks many species of maple including silver, mountain, and striped maples. The leaf infections are first small and water- soaked, but later turn brown. Distinct small, dark dots, which are fungal fruiting bodies, appear on the interveinal areas of the upper leaf surface. Premature defoliation may occur with • severe infections. Culturally manage fungal leaf spot diseases with sanitation methods. Rake and destroy infected leaves. Avoid overhead irrigation on small trees since moist leaf surfaces favor disease development. Accurate diagnosis of a maple problem is the first step in effective management. This requires thorough examination of the affected plant and complete information on its cultural conditions. You can then implement a successful manage- ment strategy to ensure long life to these beau- tiful shade trees. Carrie R. Foss is Plant Clinic Diagnostician at Washington State University, Puyallup, in Puyallup, Washington. Ralph S. Byther is Extension Plant Pathologist at Washington State University, Puyallup. References Davidson, Roy M., and Ralph S. Byther. 1991. “ Verticillium Wilt of Maples.” Extension Bulletin 0983. Pullman, WA: Washington State University Cooperative Extension. Johnson, Dennis A., and Ophardt, Marianne. 1992. “Leaf Scorch of Shade Trees.” Extension Bulletin 1422. Pullman, WA: Washington State University Cooperative Extension. Koepsell, Paul A., and Pscheidt, Jay. 1994. Pacific Northwest Plant Disease Control Handbook. Pullman, WA: Washington State University Publications. Sinclair, Wayne A., Howard H. Lyon, and Warren T. Johnson. 1987. Diseases of Trees and Shrubs. Ithaca, NY: Cornell University Press. Vol. 57:3 Fall 1994 15 JOY SPURR DANIEL J. HINKLEY top left: Acer pent aphy llum top right: A. distylum bottom: A. crataegifolium seed pods opposite: A. crataegifolium ‘Veitchii’ 16 Washington Park Arboretum Bulletin DANIEL J. HINKLEY Underused Understory: Three Maples for the Pacific Northwest by Daniel J. Hinkley Jn the woods and reclaimed -farmland of northern Michigan where I came to know trees, the maples were among my first posses- sions. Never an obsession, my intimacy with the genus has weathered the storms of a master’s thesis and deepened to a point well beyond admiration. Although I shudder to think that my musings are rife with New Age botanomorphism, maples simply are. I have no favorites, but I will not hesitate when asked to introduce a few members of the family. Heart-Shaped Leaves: Acer distylum Those who truly love plants know too well the experience of meeting a new species that titillates — that moment when, regardless of company, there is no reneging on that primal gutteral sound mounting from the inner dia- phragm. Thus it was, in that May of 1983, dazed, delighted, and fortunately alone, I made my first acquaintance with Acer distylum. The leaves of this species emerge in spring with an ephemeral dense coating of rosy golden hairs, conspicuous from some distance. As the heart- shaped leaves further expand, ultimately to six inches in length, they become fully glabrous and medium green with the petioles (leaf stalk) re- taining a nice reddish pink coloration if grown in full sun. Although many liken the foliage to that of Tilia (linden), I find comparison of a single leaf between this species and Duvidiu involucruta (dove tree) remarkably similar; the opposite leaf arrangement of the maple in situ, however, is a dead giveaway. The yellowish green flowers are produced in erect racemes in early spring as the leaves emerge. Although the sexual expression of many maple species is likely to change from year to year, Acer distylum consistently serves up per- fect flowers, i.e., with both sexual parts, and is apparently quite self fertile. The sole specimen in the Washington Park Arboretum, on the lawn between the camellia plantings and the Look- out, produces viable seeds on a yearly basis. Its offspring now grows in my garden, which in seven years (suffering less competition from taller trees) has eclipsed its parent in form and size. Even though this distinctive maple is con- sidered a tall shrub or small tree in its native habitat of Japan, the largest I have observed, in Westonbirt Arboretum in England, was nearly 40 feet in height. Spidery Foliage: Acer pentaphyUmjrt^' It was at the famous WestemHills Nursery, in Occidental, California, that I was first intro- duced to Acer pentuphyllum. In their remark- able display garden I came across a small tree in full summer dress, with leaves composed of five extremely narrow leaflets to five inches in length, which lent an air of tropical spidery- foliaged bamboo. Indeed (remember I said no favorites), I think it among the most handsome maple species for effects of foliage alone. The petioles Vol. 57:3 Fall 1994 17 DANIEL J. HINKLEY THE GATHERING GARDEN A Nursery Specializing in Unusual, Non-Intimidating HARDY PERENNIAL PLANTS • OPEN • APRIL - OCTOBER 10 AM - 4 PM • WEDNESDAY - SUNDAY OR BY APPOINTMENT 32716 68th Northwest Stanwood, WA 98292 1.206.629-2706 Association ORGANIC GARDENING The Art of Growing Healthy Plants Low Maintenance Techniques for Shrub and Perennial Beds Consultations 1 9 Y ears Experience Cherry Valley Landscaping Betty Rollefson 322-2883 Discover Us In Wallingford Garden Gifts For Garden Friends The Garden 6pot 45th & Wallingford (206) 547-5137 WATERCOLOR l] 206-328-4458 SEATTLE CAROL NEY are deep red throughout summer, even when planted in semi-shaded conditions, contrasting with the deep green leaf blades. Acer pentaphyllum possesses a short history in cultivation, in fact was only first discovered in 1929 by the American plant explorer Joseph Rock in the remote Yalung Valley of Sichuan Province. Though it is generally thought of as too tender for planting outdoors in the Pacific Northwest, my own experiences have proved otherwise. Without risking the mother plant that is lodged in our cold frame, a rooted cutting was planted out under a tall overstory of Dou- glas-firs three years ago. The yearly growth has been generous and no dieback has occurred. The tendency of this maple to leaf out extremely late (often not until early June) may explain its repu- tation for tenderness, with dormant plants chucked for dead before growth commences. The specimen in Occidental has now achieved 25 feet in height, but the ultimate size in our cooler maritime climate may prove to be much smaller. I am extremely interested in hearing from others in our area who cultivate this rare and decorative species. The Hawthorn Maple: Acer evataegifolium Acer crataegifolium , the hawthorn maple, like A. distylum , is endemic to the Japanese Archi- pelago. And, like A. distylum , the leaf shape of this species is quite unlike that of any other maple, with small three-lobed leaves to one and one-half inches in length, the central lobe ex- tending twice as long as the two side lobes. Quite superficially, the leaves are reminiscent of those of the hawthorn, genus Crataegus, and hence the specific epithet. Within the Aceraceae, Acer crataegifolium is found in the Section Macrantha, which houses the stripebark maples (e.g., Acer teamentosums A. davidiu A. pensylvanicuwL etc.) In this spe- cies, deep purple twigs become suffused with striations of white as the bark matures but never to the extent of other species grown for this effect. Though I do cultivate and admire this species as it occurs in its natural state, it is the cultivar known as ‘Veitchii’ that I wish to praise at the moment. The leaves of this selection are irregularly blotched with white and pink, like dappled sunlight caught and held on the surface of the leaves. It makes a small tree, as evidenced by a mature specimen on the south- ern bank of the Arboretum’s Woodland 18 Washington Park Arboretum Bulletin Garden, reaching less than 15 feet in height. Not only is it tolerant of shade but quite de- pendent upon it, since the leaves and bark will scorch under full sun conditions. It is greatly admired in my own woodland garden, underplanted with a froth of Tiarella trifoliate*, our native foam flower with 10-inch stems coated in white flowers, complementing the luminescence of the maple’s variegated foliage. With remarkable diversity of form and func- tion, the maples’ potential for enlivening the landscapes of our lives is enormous. I would encourage every serious Northwest gardener and horticulturist to explore this family of trees, which has long remained unchalUngpr< c\*j;hr aristocracy of the plant kingdom^ Daniel J. Hinkley’s master’s thesis, “An Interpreta- tion of the Maple Collection of the Washington Park Arboretum,” is available in the Elisabeth C. Miller Library, University of Washington Center for Urban Horticulture, Seattle. Hinkley is a member of the edi- torial board of the Washington Park Arboretum Bul- letin, writes for national horticultural publications, and is the author of Winter Ornamentals. Herron Gardens Distinctive Northwest Quality Landscaping Ann Herron 454-1216 CUSTOM DESIGN, INSTALLATION & MAINTENANCE Since 1975 herrog#i37lq Join an Ever-changing Tour of the Arboretum Sundays at One at the Graham Visitors Center 2300 Arboretum Drive East (206) 543-8801 Vol. 57:3 Fall 1994 19 Pruning Japanese Maples by Christina Pfeiffer Remove deadwood, a few crossers, and branches touching the ground. apanese maples are probably one of the most elegant garden trees grown in the Pacific Northwest. The spreading, often asymmetric, crowns trace a graceful pattern in the landscape. These trees should be pruned in a manner that respects their refined natural character. Japanese maples have an incredible range in size and form from upright to weeping, from the larger ones growing over 25 feet in height, to dwarf forms barely reaching two feet tall. Before making the first cut, study the natural habit of the plant. Look at the trunk and main branches. Pruning work should follow the natu- ral architecture of the tree, leaving it to look as though it were never touched by human han3s^ Use good sharp tools including bypass-style pruners (never use anvil-head prunersf and small hand saws. It is wise to disinfect tools between *- : — s cuts within a tree and from tree to tree if there has been evidence of Vcrticillium wilt in your garden. Isopropyl alcohol ora 10 percent bleach solution in a hand spray bottle is a convenient way to do this. Use thinning cuts to remove branches back to the point of origin, always leaving a larger branch than the one removed. Never leave stubs. Leave the branch collar intact, however, being careful not to cut flush against the trunL_^^^ What to Do First remove dead limbs and twigs; that is often all that is needed. However, many Japa- nese maples develop a dense canopy, completely obscuring the trunk and inner branches. Lightly 20 Washington Park Arboretum Bulletin KATE ALLEN, COURTESY OF PLANT AMNESTY, SUMMER 1994 thin out some of the smaller branches to reveal the architecture of the trunk and main branches. Branches ofweeping or low- growing trees that have begun to drag on the ground can be lifted by thinning out the longest branches. Next, work on any branches that may be grow- ing out of bounds from the rest of the plant or interfering with a walkway or building. Some cultivars with finely dissected or multi-colored leaves may begin to “revert” to a standard form. Any branches showing reversion should be pruned out immediately, to prevent a rapid spread throughout the entire tree. Remember to stand back frequently to look at the whole plant as you work. Be conserva- tive; do not prune out too many branches in any one season. When to Prune Be cautious about choosing the time to prune; winter isn’t always the right time. In the mari- time Northwest, with the moderate tempera- tures that occur through winter, we have seen maples pruned during winter dormancy “bleed” sap on and off all season, especially where branches larger than one inch in diameter have been removed. In some instances, this constant moisture against the bark has resulted in a die- back and poor callus formation around the prun- ing wound. For these reasons, dormant season pruning should be done in the later winter. Never prune when the buds begin to swell and new leaves are just expanding. c One of the best times to prune is in summer after the leaves have fully expanded. Pruning at this dry time of year reduces the potential for disease infection entering through the pruning wounds. It also reduces the potential for sucker responses that may occur after dormant season pruning. Deadwood is more readily apparent when the trees are in leaf. Verticillium Wilt Maples are most susceptible to Verticillium wilt. External symptoms of this vascular disease include sudden dying and wilting of an individual limb, yellow and stunted leaves, and dried up leaves that hang onto the branches into winter. Symptoms appear in early summer to autumn. Olive green, brown, and black staining are observed in sapwood of cut branches. It is important to check for these symptoms when pruning out the dead wood. This fungus lives in the soil and enters through the roots and trunk wounds. Infected trees may die slowly or rapidly. A vigorous tree often lives many years with the presence of the fungi, but remove infected branches. Christina Pfeiffer is the horticulturist of the Wash- ington Park Arboretum and an International Society of Arboriculture (ISA) certified arborist. BRANCH COLLAR Living branch Vol. 57:3 Fall 1994 Pruning on hardwoods: Leave the branch collar intact (cut A-B). Never make flush cuts (A-Z) which cause greater damage to the trunk. 21 BASED ON USDA FOREST SERVICE NE-INF-58-84 The Capricious Native: Acer glabrum ssp . doupflnsii by Mary Sue Gee /ust last summer when on a field trip in the L. T. Murray Wildlife Recreation Area east of the Cascades, I caught sight of a single, dwarf tree on the north side of a rolling hill grey-green with rabbitbrush, lupines, and asters. On examining the leaves, one to three inches wide, three -lobed and red-stalked, I realized I was looking at our third native maple, Acer £flabrum; the other two are A. circinatum , the yine maple, and A. macrophyllum , the big- leaf maple. My second encounter was closer to home, in an 106-acre parcel of wetlands, creek front, oak savannas and disturbed prairie in Pierce County. But this specimen was medium-sized, multi- trunked, and a fresh green and glaucous red — our west-side subspeci $s^-Acer gjlabrum ssp. dou£flasii({ SouglasmapleT^his maple is not common, and, when found, it is capricious in size and form, and leaf shape and color. Trees might be 10 to 40 feet high, sometimes shrub-like, and at other times, single- trunked with a narrow crown of upright branches pointing upward, the ultimate shoots colored a soft red under a waxy bloom. The small to me- dium, toothed leaves have three to five lobes, sometimes blunt and at other times pointed; the center lobe can be so deeply cut from the outer two that the leaf appears as “cutleaf.” A medium but complex green in summer, with highlights of warm hues, the leaves change in autumn. Sources of information are as variable as this maple, reporting that the foliage merely turns pale yellow, or scarlet, or orange and red. In the wild on the west side, Acer jylabrum ssp. douglasii grows on rocky cliffs, canyon sides and gulches in the Cascades, Olympics, and San Juan Islands. Closer to the Puget Sound low- lands and southwest of Tacoma is the Flett Creek parcel owned by Clover Park Technical College. Here, a bank of Douglas maple grows along the terrace break between the riverine wetland with willows and the upland of Quercus jyarryana (Garry oak). This narrow island of maples is awkward to approach. Scrambling down the slope, I encoun- Foliage and double-winged samara (seeds) of Acer glabrum ssp. douglasii on the terrace break of Flett Creek, Pierce County, Washington. tered a wall of Holo discus discolor (ocean spray) peppered with Philadelphus lewisii (mock orange). Flanking that, I tangled with thorny canes of blackberries and Rubus leucodermis (blackcap) before reaching an opening. Look- ing back up the hillside, the milky white and cream blossoms of mock orange and ocean spray created a spectacular backdrop for the grove of maples. The maples range from seedlings to saplings to old clumps with five to eight trunks often eight inches in diameter. These clumps are 20 to 25 feet high and at least that wide; they re- semble the form of vine maples with their low, round shapes and old branches inclined to the horizontal. The trees are throwing sprouts from 22 Washington Park Arboretum Bulletin MARY SUE GEE their bases, and both old and new bark have smooth surfaces grooved with minute lines. The striations contrast handsomely with the barks; old are gray on gray, and new are grayish white on wine red. Angled at about 45 degrees and maple-winged, the seeds are thick in clusters with curved tops. The leaves are three-lobed and rounded, some with red veinlets flowing into long red stalks. Easier to access are four specimens of Acer jylabrum ssp. doujylasii in the Washington Park Arboretum. One of these is located in the rock garden just north of the intersection of Lake Washington Boulevard East and Arboretum Drive East. In this rocky berm grows a speci- men, collected on the trail to Wagonwheel Lake in the Skokomish Valley bv Brian O, Mulligan , director emeritus of the Washington Park Arboretum. Planted out in the early 1950s, the tree is now 20 to 25 feet tall with one main trunk (three to four inches thick) and several young stems at its base. Its leaves have shallow lobes and seem solid green. But when the wind sways the top branches and flips the leaves undersides up, glaucous red is visible. Native plant specialist Arthur R. Kruckeberg (1982) writes that Aeer jylabrum “shows gar- den promise along with other three-leafleted small maples.” At home in exposed places — tolerant of cold weather, poor soil, drought, full sun, and strong winds-cTTouglas maple is hardyT^ Easy to grow, it can lend itself to urban gardens and city streets where planting sites have mea- ger topsoil, space, and protection. And with its “cutleaf” look, while it may not substitute for Japanese cudeaf maples, it can be a strong can- didate when selecting trees that are ecologically appropriate and that fit small, sunny gardens. Donald C. Peattie (1953) values its good looks. In A Natural History of Western Trees , Peattie remarks, “No maple can help being beautiful and even this one is no exception, with its bicolored leaves spinning gracefully on the long, slim bright red stalks.” And Brian Mulligan writes, “This is a most attractive and pleasing small tree” (1970)^ Cultivars of Douglas maple have not been selected. Appreciating the diversity of the spe- cies, careful selection could provide gardeners with an array of ornamental maples. Consider the 20 seedlings that I ordered last spring and am growing. Five are short (12 inches) with the leaves that are small, rounded and shallow Pruning with Design * S Etf 641-5220 PHILLIPS FOSS WOOD GARDEN DESIGN & CONSTRUCTION 632-6735 Nursery*Greenhouses<*Complete Landscaping Service Vol. 57:3 Fall 1994 23 AJRneJS nURS€RI€5 Over 50 years of quality plants and service Since 1940 Growers and V Propagators of Choice Nursery Stock Seattle <0- Bellevue -0- Bremerton FL©RA AND FAUNA B_a CVK_S The Northwest’s finest garden bookshop. Specializing in horticulture and nature. New and rare books. Search service and mail order. Friendly, knowledgeable staff. 121 First Ave. So., Seattle, WA 98104 (206) 623-4727 lobed. The others are two to four times taller with at least three leaf forms on several of the plants. Seedlings are easier to grow than the seeds are to germinate. Nursery people I have talked with chortled as they chatted about imperme- able seed coats requiring scarification techniques like soaking, freezing, and driving back and forth over the seeds with forklifts and trucks. They also spoke of a seed inhibitor that is partially avoided by collecting the double samara while firm and green and still on the tree. Another trick is to simply overplant; viable seeds may be sparse because of poor pollination since Dou- glas maple can produce female and male flow- ers on the same or separate plants. Advice for garden design and seed viability comes from Mr. Mulligan. “Because of its natu- ral habit, it would seem best to plant it in groups or clumps rather than as isolated specimens and this might also aid in the production of fertile seeds” (1970). My seedlings are ready to plant out this fall. I have space and sites to spare in my garden for all three native maples. Vine maples on the up- land in the shade of Douglas-firs ( Pseudotsuga menziesii). Bigleaf maples edging the Douglas fir- Garry oak woodland and self- sowing down into the drainage basin. Farther east in the gully, a slope of gravelly, sandy loam begs for a bank of Douglas maple. I want to look out my bay windows and see maple leaves playing against blossoms of ocean spray and mock orange. To walk along this gully, protected. To feel the smooth leaves and bark. To enjoy a variety of Douglas maple and other companion plants that also like open and drier sites with fast drainage, such as madrone ( Arbutus menziesii ), service- berry (Amelanchier alnifolia) , Oregon grape (. Mahonia aquifolium ), and the Nootka rose (Rosa nutkana). I won’t be in a rush to plant other associates such as snowberry, blackcaps and blackberries; I want to manage the hordes crawl- ing out of the woods, up from the urban park- ing lot below, and over neighboring fences. The author wishes to acknowledge the assis- tance of Nancy White at Clover Park Technical College, Brian Mulligan and the staff at Wash- ington Park Arboretum, and the staff at Elisabeth C. Miller Library. Mary Sue Gee writes from Tacoma, Washington. 24 Washington Park Arboretum Bulletin Viewing Douglas Maple KING COUNTY: WASHINGTON PARK ARBORETUM LOCATION: 2300 Arboretum Drive East, Seattle OPEN: Daylight hours DIRECTIONS: From Interstate 5, take the East Madison Street exit. Follow East Madison Street, turn right on to Arboretum Drive East. LANDSCAPE: Direcdy inside the Arboretum and north of the intersection is a rock garden. Park in the closest lot and walk back down the road. In this rock garden just north of the Hillside Trail is Douglas maple next to a large pine. See the map in the newly published The Woody Plant Collection in the Washington Park Arboretum in the Graham Visitors Center for more locations. PIERCE COUNTY: CLOVER PARK TECHNICAL COLLEGE LOCATION: 4500 Steilacoom Blvd S.W., Tacoma OPEN: 8 to 5 weekdays DIRECTIONS: From Interstate 5, take exit 127 and go south on South Tacoma Way. Turn west on Steilacoom Boulevard. Clover Park Technical College is on the south side of the road with visitor parking. LANDSCAPE: A bank of maples between the Garry oak upland and the Flett Creek wetland. This parcel is privately owned by CPTC and is not open to the general public at this time. For permission to view, call and make arrangements with Nancy White at (206) 589-5590. PIERCE COUNTY-KING COUNTY: THE INTERPRETIVE CENTER AT FEDERATION FOREST STATE PARK LOCATION: 17 miles east of Enumclaw on Hwy 410 OPEN: Day use only DIRECTIONS: Take Highway 410 southeast towards Yakima. About 17 miles east of Enumclaw, turn south into the park. The Catherine Montgomery Interpretive Center is near the entrance and has commodious parking lots. LANDSCAPE: One Douglas maple is planted in the “yellow pine zone” in front of the Center. The park contains 612 acres of virgin trees with superb specimens of old Sitka spruce, Douglas fir, and red cedar on easy, well-groomed trails. PIERCE COUNTY: THE NORTHWEST NATIVE GARDEN LOCATION: Point Defiance Park, 5400 Pearl Street, Tacoma OPEN: Sunrise to one-half hour after sunset DIRECTIONS: From Interstate 5, take exit 131 towards Highway 16 west. From this spur, take the exit for 6th Avenue and Point Defiance Park, turn left on to 6th Avenue and shortly turn right on to Pearl Street, which leads directly to the park. Inside the park follow the one-way road around and behind the zoo, heading back towards the entrance. Right before the entrance/exit is the Northwest Native Garden. LANDSCAPE: Established in 1964 by the Tacoma Garden Club, the exhibit area is one and a half acres planted in six geographical zones. Two specimens of Douglas maple are up the grade and toward the right. OLYMPIC MOUNTAINS: CLALLAM COUNTY LOCATION: Three O’Clock Ridge in the Buckhorn Wilderness near Mt. Maynard, Cougar Creek, Bungalow Creek and Dungeness River SOURCE: Jerry Gorsline, Nelsa Buckingham, and a USFS ecologist OLYMPIC MOUNTAINS: CLALLAM COUNTY LOCATION: Crystal Creek area where maples are visible from the Olympic Hot Springs Road SOURCE: Nelsa Buckingham OLYMPIC MOUNTAINS: CLALLAM COUNTY LOCATION: Trail to Mt. Townsend SOURCE: Daniel J ^in^Y— , OLYMPIC MOUNTAINS: JEFFERSON COUNTY LOCATION: Trail to Mt. Juniper SOURCE: Daniel J. Hinklev _ OLYMPIC MOUNTAINS: MASON COUNTY LOCATION: Trail to Wagonwheel Lake north of Lake Cushman in the Skokomish River Valley SOURCE: Brian O. Multigft-rr CASCADE MOUNTAINS: SNOHOMISH COUNTY LOCATION: East of Granite Falls along Perry Creek in the Stillaguamish River Valley SOURCE: Arthur Kruckeberg Nursery Sources of Douglas Maple Call first to inquire about supply of seeds or seedlings. Frosty Hollow: Box 53, Langley, WA 98260; (206)221-2332 (seeds). Plants of the Wild: PO BOX 866, Tekoa, WA 99033; (509) 284-2848 (plants). See Hortus Northwest in the Elisabeth C. Miller Library for several other suppliers. References Kruckeberg, Arthur R. 1982. Gardening with Native Plants of the Paeifie Northwest. Seattle: University of Washington Press. Mulligan, Brian O. 1971. “Maples in the North- western USA.” International Dendrology Society Yearbook 1970. London: Intn’l Dendrology Soc. Peattie, Donald C. 1953. A Natural History of Western Trees. Boston: Houghton Mifflin Co. Vol. 57:3 Fall 1994 25 In the Washington Park Arboretum by John A. Wott Visit the Japanese Maples On its(200jxjres near the heart of Seattle, the Washington Park Arboretum displays nearly C 4500 different taxa of trees, shrubs, and vines. One of the major collections, the Japanese maples (Acer palmatum ), is located in the Woodland Garden, a historic feature of the Arboretum. The Woodland Garden is a highly visited area, especially during the fall color season. The gar- den runs along a narrow valley with a pond (cleaned and repaired this summer) at either end, connected by a flowing stream. With its water features, tall conifer overstory, and two fairly steep slopes flanking its center, the valley is a very suitable setting for the display of plant spe- cies well adapted to a woodland setting. We believe that no other public garden in the United States contains a collection of Japanese maples even half as large as ours. Furthermore, few gardens in this country have a climate as suit- able for growing Japanese maples as we have in Seattle. Our collection contains nearly 170 species, varieties, and cultivars, with 132 planted in the Woodland Garden. Maple authority J. D. Vertrees lists approximately 250 taxa of Japa- nese maples in his monograph, Japanese Maples. Maple Evaluation In l%94, the Arboreturnreceived a S25.Q00 conservation grant from the Institute of Museum Services for improving the curatorial evaluation, verification, and cultural evaluation, for site improvements, and to determine which accessions are worthy and/or unhealthy^-— — Acer palmatum in the upper pond area in November 26 Washington Park Arboretum Bulletin JOY SPURR \ PHOTO BY JORDAN REAMS, UW PHOTOGRAPHY During the summer of 1994, two interns — Julie Palasma and Kim Anderson, under the su- pervision ol Tracy Omar, assistant curator and recorder — each spent eight weeks evaluating the Japanese maples in the Arboretum. Following is a summary of their reports. Julie Palasma first evaluated the condition of each tree, classifying it as in very good, good, fair/good, fair, or poor condition. Poor trees had over 30 percent dead wood. They were often found in crowded and shaded sites, which resulted in distorted growing habits and signs of disease. Of the 170 trees evaluated, only three percent were very good, while 80 percent were fair to good. The other 17 percent were judged fair to poor. Crowding and shading were the most com- monly cited problems in the Japanese Maple Collection. Often, large amounts of deadwood were found in the lower branches. In some areas, certain specimens were no longer visible from the paths. This is especially noticeable in grid 32-B, which is on the north-facing slope just south of the west (lower) pond. This area is completely shaded by the large red cedars, Douglas-firs, and hemlocks, which have grown tremendously since the Japanese maples were originally planted. Julie also classified the trees into 13 different morphotypes, depending on the type and color of leaves and growth habit. The majority (52 percent) of our collection is comprised of green- leaved types. The rest are 15 percent red leaved, 16 percent variegated leaves, and the remain- der are either dissected, linear lobed, weeping, or dwarf. Acer palnwtum cultivars are propagated pri- marily through grafting, thus each new plant is genetically identical with the “mother” plant. If propagated by seed, the species produces many different variations, mostly in the foliage. Kim Anderson wrote that it was this predisposi- tion for mutation “that has allowed the wide, diverse selection of cultivars that exists today to arise.” In her summer survey, Kim noted that per- haps nearly 5f)_percent of the collection was no longer the actual described cultivar. This has occurred through four different ways. The most common is a failed graft in which the scion dies and the shoots from the understock become the dominant plant. MADISON PARK HARDWARE 1837 42nd E. 322-5331 GARDEN SUPPLIES • PAINTS • TOYS • GIFTS Second, cultivars from bud-sport material are unstable and quite often revert back to the typi- cal green-leaved shoot, which is more vigorous. Over time, the more vigorous green shoots be- come dominant. In some instances, the original plant may have died, and a seedling may have grown up in the same spot, then been labeled with the original plant’s name without further verification. Finally, we are also aware that a number of cultivars originally obtained as seed were origi- nally listed as “plants,” which means they may have hern seedlings and not grafted. JThe origi- nal plant may not have been a cultivar but a wild type seedling. As fall progresses, we will continue to verify specimens in the Maple Collection. Fall color is one of the definitive characteristics for cultivar identification. Currently, as you walk though the Woodland Garden, you will note that there are red and blue ribbons on the trees. In this wav, we are more easily able to review the plants and eventually we will remove aging cultivars that cannot be verified and replace them with newer authentic cultivars. Continued on next page. Vol. 57:3 Fall 1994 27 It is apparent that a cultivar collection of this type requires more attention at regular intervals, especially in regard to verification of the plants. This is especially true of the Japa- nese maples, which are very prone to reversion and sometimes can almost “change” their identity overnight. Pond Cleaning Continues Pond cleaning, through funds raised by The Arboretum Foundation, continued during August and September. The cleaning of the lower pond in the Woodland Garden was done with Sonneman Design, Inc., in charge. Christina Pfeiffer, horticulturist, and Polly El Aidi, landscape architect, were instrumental in leading the cleaning and design process. There was much more “spoil” in the bottom of the lower pond than expected, so it was taken to the “flats” where it is being spread and seeded over with turf grass. A number of large stones were set along the southern section, and many small rocks were added to the spillway. The over- flow drainage standpipe was removed and short- ened. Special fittings were needed in order to connect the new pipes into the old wooden pipe, which drains under Azalea Way. A viewing deck is being built, to hide the drain and to provide access to the water. A number of ferns, selected with the consultation of Judith Jones, Barfod Ferns, are being planted along the pond edge. Vandalism The problems of the inner city have now reached the Arboretum. Since August, vandals have driven through collection areas in the Mulligan Sorbus Collection and in Azalea Way sometime during the evening hours. Several valuable plants have been destroyed, signs have been damaged, and turf areas injured. Pacific Northwest Garden Network A leaflet that will list all area gardens will be published by the Pacific Northwest Garden Network. The publication, which gives recip- rocal perks to Network members, is the result of a meeting of 13 Northwest public garden di- rectors, including myself, which was held at Tacoma’s Lakewold Gardens in September 1994. John A. Wott. PfP.. is director of Arboreta, Wash- ington Park Arboretum, and professor of Urban Hor- ticulture, CUH, University of Washington, Seattle. The UW manages the collections and the associated arboretum programs, and works cooperatively with City of Seattle and The Arboretum Foundation. 28 Washington Park Arboretum Bulletin EMMONS © 1992 Book Review Maples of the World D. M. van Gelderen , P C. de Jong, and H. J. Oterdoom. Theodore R. Dudley, Ph.D., scientific editor. Photographs by J. R. P van Hoey Smith. Line drawings by Inez Langevoort-de Maare. Portland , OR: Timber Press , 1994. $59.95. ISBN 0-88192-000-2. From a distance, the family of maples (Aceraceae) appears neat and easily discernible with only two genera included: Acer , the maples, and Dipteronia , a genus of two species, one of which — D. sinensis — is represented in the Arboretum’s collection. Closer inspection, however, re- veals an enormous jigsaw puzzle, which has been awk- wardly pieced together begin- ning as early as the 5 th century B.C. with Pliny the Elder. Since the heart of the geographic range of maples lies in the still relatively unexplored regions 6f China, jhqse first delving into this genus had available to them a paucity of material to study. Now, nearly 2500 years later, the first compre- hensive treatment of this remarkable family has been published. Nineteen years of meticulous research by maple authorities from around the globe has culminated in a treatise that brings into focus an image that has long been clouded by inexactitude. There are few places that this tome could be more appreciated than in the Washington Park Arboretum. We boast one of the hsat public collections of maple species in North America, with over 125 species, subspecies, cultivars7 and hybrids represented. In addition, there are numerous cultivars of Acer palmatum , the Japanese maple, found in the Woodland Garden as well as in the Japanese Garden. Not only does this book set a standard for nomen- clature from which to better interpret this collection but also makes apparent the absence of numerous ornamental species not currently found in the collection. With a plethora of recently published garden- ing books whose main entrees seem nothing more than an overpolished day in the garden, it is exciting to find such a substantive reference book with generous servings of gutsy informa - tion. Whereas this work is invaluable in a research collection or in the plant collector’s and nurseryperson’s shelf, I suspect it would find infrequent use by the lay horticulturist. Though I do not find this objectionable, the appearance of a last minute attempt to broaden the audi- ence by including feeble sections on landscap- ing with maples as well as propagation only detracts from the work. For those, however, with more than a passing interest in evolution, the marvelous intricacies of repro- duction, or the exasperating details of why plant names change, there are days of entertainment here. The two hundred plus color photo- graphs are superb. The exhaustive reworking of the Aceraceae found within these pages is at first dangerous to those with a little bit of knowledge. Acer ginnala has been reduced to subspecies rank of Acer tataricum as has Acer grosseri (to Acer davidii) and A. lobelii ( to A. cappadoeicum) . Dipteronia , the only other genus in Aceraceae, is somewhat ambiguously cast adrift towards the closely allied Sapindacaeae. It is precisely this reworking, however, that has made this publi- cation so significant. Taxonomists and horticul- turists at last have a common point of departure from which to explore a remarkable family of trees .-^reviewed bv Daniel J. Hinkley Acer tataricum ssp. ginnala Daniel J. Hinkley is co-owner of Heronswood Nursery, Ltd., instructor at Edmonds Community College, and author of numerous articles on horti- culture. He wrote Winter Ornamentals (Sasquatch Books) and is on the editorial board of the Arbore- tum Bulletin as well as a member of The Arboretum Foundation board. Maples of the World D. M van Gelderen P C de long H. J. Oterdoom photographs by J . R R van Hoey Smith Vol. 57:3 Fall 1994 29 INEZ LANGEVOORT-DE Acer tataricum ssp. ginnala For Further Information: Maples by Valerie Easton aples in all their variety and plenitude have not been abundantly written about. The International Maple Society, which publishes a newsletter, can be reached in care of Mr. Peter A. Gregory, 3 Park Close, Tetbury, Gloucestershire, GL8 8HS, United Kingdom. Listed below are books and journal articles that can be found in the Elisabeth C. Miller Library. Bean, W. J. Trees and Shrubs Hardy in the British Isles. 8th ed., revised. New York: St. Martin’s Press, 1981. Vol. 1 and supplement, 1988. Grant, John A., and Carol L. Grant. Trees and Shrubs for Pacific Northwest Gardens. 2nd ed. Portland, OR: Timber Press, 1990. Hinkley, Daniel J. “An Interpretation of the Maple Collection of the Washington Park Arboretum.” Master’s thesis, University of^> v Washington, 1985.^^ " — Jacobson, Arthur Lee. Trees of Seattle. Seattle: Sasquatch Books, 1989. Mulligan, Brian O. Maples Cultivated in the United States and Canada. Lancaster, PA: American Association of Botanical Gardens and Arboretums, 1958. Phillips, Roger. Trees of North America and Europe. New York: Random House, 1978. Van Gelderen, D. M., P. C. de Jong, and H. J. Oterdoom. Maples of the World. Portland, OR: Timber Press, 1994. Van Pelt ^nhejF^Washinatnn Biff Tree Program 1994. Seattle, WA: College of Forest Resources, University of Washington. 1994. Vertrees, J. D. Japanese Maples: Momiji and Kaede. 2nd ed. Portland, OR: Timber Press, 1987. Journals Arb or i cultural Journal , The International Journal of Urban Forestry. Oxfordshire, England: AB Academic Publishers. International Dendrology Society Yearbook 1970. London: International Dendrology Society. Pacific Northwest Trees: International Society of Arboriculture, Pacific Northwest Chapter. Valerie Easton is a librarian at the University of Washington Center for Urban Horticulture. 30 Washington Park Arboretum Bulletin JOY SPURR New on the Shelves of the Elisabeth C. Miller Library by Valerie Easton useful new list by a local plant society, two new books on how to use plants in the garden, and a colorful children’s book inspired by a Seattle community garden are high- lights of new books in the library. Bath, Trevor, and Joy Jones. The Gardener’s Guide to Growing Hardy Geraniums. Portland, OR: Timber Press, 1994. ISBN 0-88192-278-1. This is the best kind of plant book, well and knowledgeably written, with photographs that clearly show color, form, and — most impor- tantly— combinations for garden building. Hardy geraniums, “the little black dress of the garden,” mix beautifully with shrubs, annuals, perennials, and roses to knit borders together and enhance the color and foliage of larger, showier plants. The authors, along with other enthusiasts, describe how to grow and propagate over 200 kinds, and the assortment of colors, foliage, form and texture, growth habit, and growing condi- tions should promote much greater use of these versatile plants. Conder, Susan. V drieg ate d Leaves: The Ency- clopedia of Patterned Foliage. New York: Macmillan, 1993. ISBN 0-02-527330-2. Some gardeners tend to have a slightly scornful atti- tude about variegated plants, but the role that light- splashed foliage can play in creating a beau- tiful garden is well illustrated here in text and photographs. Dark corners of the garden glow with golden-leaved Hosta fortunei ‘Albopicta’, and even nasturtiums look new and interesting with marbled leaves. Close-up photos have the reader marveling at the perfection of the burgundy-trimmed leaves of Epimedium diphyllum , the sheer golden gaudiness of an entire hedge of Ilex aquifolium ‘Golden King’, and the slightly more subtle beauty of Actinidia kolomikta or Berberis thunbergii ‘Rose Glow’. The author discusses how to use the seem- ingly endless variety of leaf pattern and color to create light, contrast, depth, and movement in the garden as well as to enhance the bloom, color, and shape of plain-leaved plants. Northwest Perennial Alliance. The Northwest Perennial Alliance Drought-Tolerant Data Base: Water Conserving Plants for the Pacific North- west West of the Cascades. Seattle: Northwest Perennial Alliance, 1993. No ISBN. This thor- ough and impressive list was prepared by a group of amateur and professional gardeners and land- scape designers interested in growing a wide variety of hardy, drought- tolerant plants in the Northwest region west of the Cascade moun- tains. Plants are listed alphabetically by botani- cal name, with a brief description, common name, type of plant, height, cultural informa- tion, bloom time, and water requirements (once established, “xeric” plants need no supplemen- tal water, and “low water” plants require monthly watering). The listing by type of plant enables you to flip to grasses or bulbs, for example, to quickly see if a plant you are considering is drought tolerant. If you have ideas for future additions to the plant list, there are forms in the back to send in with your suggestions. To order, send a check made out to Northwest Perennial Alliance for $15 ($12 plus $3 postage and handling) to NPA, PO BOX 45574, University Station, Seattle, WA 98145. Please enclose a note with your mailing ad- dress and state that the check is for a copy of this book. Vol. 57:3 Fall 1994 31 COURTESY, UNIVERSITY PHOTOGRAPHY, UW Schaefer, Carole Lexa. In the Children’s Gar- den. New York: Henry Holt, 1994. ISBN 0-8050-1958-8. A Northwest gardener was in- spired to write her first picture book by the children’s garden at Tilth in the Good Shep- herd Center, in Seattle’s Wallingford district. To capture the author’s vision, a New York illustra- tor visited Seattle, and the result is a beautiful, fun-to-read book. Bright colors blurred with im- pressionistic lines give the feel of high summer and the mystery of corn and sunflowers grow- ing many feet above a small person’s head. The fun of children working together, the richness of “deep, dark dirt... tunneled through by worms,” and the sights and smells of vegetable gardening are brought to life for young children. Also New Bridwell, Ferrell M. Landscape Plants: Their Identification , Culture, and Use. Albany, NY: Delmar Publishers, 1994. ISBN 0-8273-6017-7. The California Center for Wildlife. Living with Wildlife. San Francisco: Sierra Club Books, 1994. ISBN 0-87156-547-1. Howells, John. Growing Clematis. London: Ward Lock, 1994. ISBN 0-7063-7238-7. Monroe, Enid. An Artist in the Garden. New York: Henry Holt, 1994. ISBN 0-8050-2718-1. Obrizok, Robert A. A Garden of Conifers: Introduction and Selection Guide. Deer Park, WI: Capability’s Books, 1994. ISBN 0-913643-08-4. Thompson, Peter. The Propagator’s Handbook. North Pomfret, VT: Trafalgar Square Publish- ing, 1993. ISBN 0-943955-69-6. Thorpe, Patricia. Growing Pains: Time and Change in the Garden. New York: Harcourt Brace, 1994. ISBN 0-15-176652-5. Verey, Rosemary. Secret Gardens: Revealed by Their Owners. Boston: Little, Brown, 1994. ISBN 0-8212-2074-8. Note The rose illustrated on the cover of the spring 1994 issue as Rosa eaudata has been reidenti- fied from fresh living material as Rosa moyesii, a well-known species from China. This is a particularly fine form of it, worthy of a clonal name to distinguish and perpetuate it. — Brian O. Mulligan, August 26, 1994. CULTIVATED PALATE A cookbook for today's fast-paced lifestyles and a perfect gift! featuring Joy Spun's color photos of Arboretum collections Available at the Arboretum Foundation Gift Shop and other fine stores or by mail order 206-325-4510 all funds raised by cookbook sales benefit the Washington Park Arboretum discounts for volume sales m * 32 Washington Park Arboretum Bulletin ill February 22-26, 1995 • Convention Center • Seattle ^Northwest ^ , Flowery and Garden Show SHOW HEADQUARTERS • FAX [20G] 784-554S • PHONE [20G] 789-5333 Advance tichets available at baimkb branches. Vol. 57:3 Fall 1994 33 ARBORETUM The Bulletin is published by The Arboretum Foundation Washington Park Arboretum University of Washington XD-10 Seattle, WA 98195 Nonprofit Org. US Postage PAID Seattle, WA Permit No. 126 An arboretum: a living museum of woody plants for education, conservation, research, and display. On'n & Atthea Soest 346 Morgan Drive Sequim WA 98382 13953 * 3/1/95