W 7 x Tuf^fT i \ 4 m! ^1 WBuSi ■ y-* * 4 i | * • i t ( ! i j Bfcm, 1.^-3 «M I A‘ \ '* M' ® Fa Officers of The Arboretum Foundation Mary Thorne President Vice Presidents: Bill MacKay Administration Janet Patrick Unit Council Mary Booth Special Events Duane Kelly Long-Range Planning Cecilia Buck Secretary Keith Patrick Treasurer Richard Doss Immediate Past President Rae Tennyson Executive Secretary Pamela Tharl Bookkeeper Editorial Board of the Arboretum Bulletin Jan M. Silver Editor Jeannine Curry, Secretary Kelly Dodson Valerie Easton, Book Review Editor Timothy Hohn Steven R. Lorton Virginia Morell Brian O. Mulligan Jan Pirzio-Biroli Mary Robson Barbara Swift Matsuo Tsukada, Ph.D. Harold B. Tukey, Jr., Ph.D. Richard Walker, Ph.D. Advertising Director Susie Marglin (206) 325-4510 Center for Urban Horticulture Harold B. Tukey, Jr., Ph.D. Director of Arboreta Brian O. Mulligan Director Emeritus The Washington Park Arboretum Timothy Hohn Curator, Plant Collections John A. Wott, Ph.D. Professor Continuing Education Lynda J. Ransley Coordinator Concerning This Issue . . . Color, texture, and variety in the garden throughout the year — the gardener’s hope and challenge which we ad- dress in this and the next issue. The challenge is met on these pages by Mareen Kruckeberg who discusses the value of ever- green oaks in the landscape. Dan Hinkley also barks up the right tree in “Coats of Many Colors,” which presents his sug- gestions for trees that display bark with a bite. Both articles are illustrated by the photography of another precious year-round resource, photographer Joy Spurr of Unit 81 whose plant por- traits appear all over the world. A generous and well-organized spirit, Joy has been helping The Arboretum Foundation and the Bulletin with diverse photographic needs. Before a recent trip abroad, Joy took time to photograph trees, leaf, and bark that you will see on these pages. The excitement of Fall will eventually detour into a fallout of leaves, before heading into winter. Seattle Tilth compost expert Madelon Bolling reports on making good mulches from leaves for trees. In 1942, Arthur Dome first wrote about heaths and heathers for the Bulletin. In this issue, Art updates us on late summer and fall blooming hybrids. We hope to hear from him again before another 50 years elapse. The definition of arboretum appears on the back panel of this and each issue, a policy buttressed by Curator Timothy Hohn’s strong sense of its value. Two articles in this Bulletin highlight the critical relationship between the research aspect of xhe arbo- retum definition and its conservation side. To start with, is re- search done on birds in the Arboretum. Magellanic penguin expert P. Dee Boersma and student Kama Almasi wanted to see whether birds prefer native or introduced conifers. Although there are no penguins in Arboretum trees, observations were made of many other native and introduced bird species in these conifers. The study concludes that we need to keep bird prefer- ences in mind so that their populations thrive; when this hap- pens, they will continue their crucial tasks of dispersing seeds, eating insects, and adding beauty to our landscape. Also featured is the work of Clement Hamilton, University of Washington Center for Urban Horticulture. Hamilton ex- plains how he, a Seattle-based researcher, can conduct science that contributes to the diversity and survival of tropical forests. Our seasonal update on the Arboretum and books to consider for gifts round out this issue. Continuing the earlier discussion of ‘ ‘ barking up the right tree,” we are pleased to welcome four new editorial board members: Kelly Dodson, Jan Pirzio-Biroli, Mary Robson, and Barbara Swift. Also, we can report that the last issue, on dry gardening in the Pacific Northwest, was requested by many municipalities. The editorial board of the Bulletin promises to continue reporting on hands-on solutions surrounding this ap- proach to horticulture because we like to think that we can make a difference in the Washington Park Arboretum. Jan Silver, Editor The Washington Park Arboretum Bulletin ELISABETH C. MILLER LIBRARYPrinted on recycled gloss-coated CENTER FOR URBAN HORTICUfeMftSnimum 50% waste paper) UNIVERSITY OF WASHINGTON, GF-15 SEATTLE, WASHINGTON 98195 will CONTENTS 2 . . . Late Summer & Fall Blooming Heathers by Arthur P. Dome 5 An Answer to Autumn: Leaf Compost and Mulch by Madelon Bolling 7 Can Birds Tell the Difference between Native and Introduced Conifers in the Arboretum? by P. Dee Boersma and Kama N. Almasi 10 Coats of Many Colors by Daniel ]. Hinkley 14 Ornamental Bark in the Washington Park Arboretum photo essay by Joy Spun 16 . Evergreen Oaks for Northwest Gardens by Mareen Kruckeberg 20 Psychotria and the Conservation of Tropical Biodiversity by Clement W. Hamilton 23 In the Washington Park Arboretum by Timothy Hohn and Christina Pfeiffer Book Reviews: 25 Designing with Perennials reviewed by Pat Roome 26 . . . Mushrooms of North America reviewed by Coleman Leuthy 26 New on the Shelves of the Elisabeth C. Miller Library by Valerie Easton Coming in the next issue: The Northwest Winter Garden Cover: During a recent autumn, David McDonald photographed thisSbr- bus scalaris hybrid in the Brian O. Mulligan Sorbus Collection, Washing- ton Park Arboretum. According to Director Emeritus Mulligan, this tree was raised in the Arboretum from seeds received in 1958 under the name of S. scalaris , sent from a garden in England. The cover hybrid is similar to this species of Chinese origin, but not correct in all characteristics. Backdrop: The trunk of Acer tegmentosum, in the Arboretum. Photo by Brian O. Mulligan. The Washington Park Arboretum Bulletin is published quarterly, as a bonus of membership in The Arboretum Foundation. 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 projects. The Washington Park Arboretum is administered through cooperative efforts between the University of Washington, its Center for Urban Horticulture, and the City of Seatde Department of Parks and Recreation. The programs and plant collections are a responsibility of the Center for Urban Horticulture. For membership information, write to The Arboretum Foundation, University of Washington (XD-10), Seattle, WA 98195 or call (206) 325-4510. Articles on gardening and horticulturally related subjects are welcome. Please call for guidelines. For permission to reprint any part of the Arboretum Bulletin , please contact the Arboretum Foun- dation for written permission. © 1991 The Arboretum Foundation. For information about the activities of The Arboretum Foundation,, call (206) 325-4510. To receive information about public programs and lectures of the Center for Urban Horticulture, please call (206) 543-8800 or 545-8033. Late Summer & Fall Blooming Heathers by Arthur P. Dome An asterisk (*) indicates species, including varieties and/or forms, that can be found in the Washington Park Arboretum. The late summer and fall blooming heaths (Erica) and Scotch heathers (Calluna) are a valuable asset to any gar- den. They are colorful and easy to grow, and blooms are not damaged by early frosts. These plants can do very well for any garden- er who heeds their few re- quirements. All they need is a location that al- lows at least half a day of direct sun light, when the sun shines. Generally, they should have a light, friable, lime-free, well- drained soil that never dries out. Most types should be sheared back in the spring, especially while they are still young. This prevents Erica plants from becom- ing loose or leggy and/or to keep them in bounds. The majority of Calluna foliage needs shearing to where the previous sea- son’s blooms started. Under these condi- tions, heaths and heath- ers can do an excellent Erica cincrea ‘Eden Valley’ and blossom colors complement each other and offer a variety of blooming plants year-round. Heaths and heathers also can make ideal compan- ion plants for azaleas, rhododendrons, kalmias, job of replacing herbace- ous perennial and annual plants that require a great deal more attention. They can be used in rock- eries, in shrubbery borders, or along walks and drives in the open. Some gardeners like to plant an area with a selection in which the size, foliage, 2 Washington Park Arboretum Bulletin Arthur P. Dome Glossary Ericaceous refers to a member of the Erica- ceae family of plants. Friable indicates loose and crumbly soil. and other plants that have the same cultural re- quirements. The Heaths Erica cinerea is considered a late spring and summer blooming species, but it does have some cultivars that flower up into October and Novem- ber. They usually grow from 4-12" tall and some can spread to 30" across. A few of the more desir- able, longer-flowering cultivars are: ‘Apple Blos- som’, which has light shell-pink blossoms; ‘C.D. Eason’, with bright magenta blossoms; ‘Con- stance’ with beet-root colored blossoms and gold- en foliage; ‘Eden Valley’, with bi-colored lavender and white blossoms; ‘P.S. Patrick’ with vivid pur- ple blossoms; and ‘Violacea’ with deep violet- colored blossoms. Erica tetralix cultivars bloom from June into October. Different ones can grow from 6-12" high and spread up to 15 inches. This species has forms with foliage color ranging from olive to gray to silvery. Two of the most popular are the cul- tivar ‘Alba mollis’, which has pure white flowers with silver-colored foliage and ‘George Frazier’, with light pink blossoms and olive-green foliage. From July through October, Erica ciliaris has cultivars that bloom. They usually grow from 8-12" tall and some can spread up to 24 inches. A few of the more desirable cultivars are: ‘Corfe Castle’, with rose-pink blossoms; *‘ David Mc- Clintock’, which has white blossoms with deep pink tips; and ‘Stoborough’, an upright grower with white blossoms and light shell-pink blooms. Also blooming during this time are Erica vagans cultivars. Different ones grow from 9-24" Photo, opposite page: Erica cinerea ‘Eden Valley’ reaches six inches in height with abundant flowers and a spreading habit. Find heathers in the Arboretum on the south side of Rhododendron Glen and at the south end of the Joseph A. Witt Winter Garden. tall and can spread up to 30 inches. Some of the more desirable cultivars are: ‘George Under- wood’, with pinkish blossoms; *‘Lyonesse’, with white blossoms; *‘Mrs. D.F. Maxwell’, with deep rose-pink blossoms and * ‘St. Keverne’ with pure pink blossoms. One of the most satisfactory of all cultivars is Erica x darleyensis . It can start blooming in Octo- ber with some cultivars still flowering in May of the next year. Also, these cultivars are the most adaptable when it comes to soil types and loca- tions. The size of growth ranges from 8-18" tall, with a spread up to 36 inches. The early fall- blooming cultivars are: *‘Alba’, with white blooms; * ‘Darley Dale’, with light lilac-pink blos- soms; * ‘Furzey’, with deep lilac-pink blooms; and ‘George Rendall’ and ‘Ghost Hills’, both of which have deep pink blossoms. True Scotch Heathers The true Scotch heather is Calluna vulgaris. This is a very diverse group of plants that are well adapted to most of the temperate zones of the United States. One can grow plants that are dou- ble flowered, single flowered, miniature or dwarf, and prostrate to tall. At different times of the year, the foliage of the various Scotch heathers can vary from light green to dark green, olive colored to sil- very gray, yellow to golden, and russet to red. The Scotch heathers with double blossoms are usually the most popular. Starting in July, ‘Coun- ty Wicklow’ is a neat little shrub with shell-pink blossoms and bright green foliage that grows about 12" tall with a spread of 20 to 24 inches. Also starting in July, ‘Kinlochreul’ has the same growth habit but with pure white flowers. The ‘J.H. Hamilton’ is usually a little smaller grower with olive-green foliage and pink blossoms in late July. The old-time ‘H.E. Beale’ can have long sprays of light lavender-pink blossoms 12-14" long. These double-flowering forms can really en- hance small floral arrangements and corsages. If you would like some of the taller, more up- right growing Calluna of 24 inches or higher, you can find them in a range of colors, starting in August. ‘Alportii’ has crimson blossoms and dark green foliage; ‘Mair’s Variety’ has the dark green foliage, but pure white blossoms. For laven- der blossoms, select ‘Aberdeen’ with its gray foliage or * ‘Silver Knight’ with its silver-gray foliage. These plants are good for covering large areas in a hurry, but can be kept in bounds with pruning. They also can be used as background Vol. 54: 3/Fall 1991 3 LLJ. : 1> r AA — 1 1 r 1 , GARDEN y \ WOODWORK f Design & Construction •Trellises ‘Arbors •Fences ‘Gates •Privacy Screens •Vertical Gardening Projects ^ I Bill Longer [ r 324-7096 Herron Gardens Distinctive Northwest Quality Landscaping Ann Herron 454-1216 vi CUSTOM DESIGN, INSTALLATION & MAINTENANCE Since 1975 herrog#i37LQ plants for smaller shrubs, etc. Select whatever foliage or blossom color fits into your program. The miniature or dwarf Calluna are interesting all year long because of their growth habits, not their blossoms. Some to consider that rarely get over 4 tall are ‘Foxii Nana’, ‘Minima Smith’s Variety’, ‘California Midge’, and ‘Sedlanov’. They are most interesting where they can be grown as individuals and not allowed to grow to- gether or be crowded out by faster growing plants. You may like the prostrate growing types of heath, usually in the 2-4" high range, that are more prolific bloomers. Around the end of July, ‘Mrs. Ronald Grey* has mauve blossoms, and ‘White Lawn' its white bloom and bright green foliage. In August and September, ‘Sister Anne' shows her light mauve-colored blossoms and a sil- very type foliage. These heaths are nice to use with steps and stepping stones. The Calluna that have foliage colors in various shades of yellow, gold, russet, and red at different times of the year always create a lot of interest. The quality of these colors in the spring are really enhanced when the weather is bright and sunny and the air is near freezing. Although the blos- soms of these plants are insignificant, the follow- ing cultivars grow about one-foot tall and twice as wide and can be quite showy in the late summer and fall: ‘Aurea', with mauve blossoms; ‘Beoley Gold’, with white blossoms; and * ‘Blazeaway’, with pale lavender blossoms. Heaths and heathers offer more than their color and hardiness. They provide Northwesterners numerous opportunities to enhance the year- round desirability of their gardens with a com- paratively small amount of effort and money. The Herbfarm awaits you just 30 minutes from Seattle in Fall City. Explore the gardens and choose from 639 varieties of perennials, annuals, vegetables, and herbs. Open everyday, 9-6. Now Open . . . Woodland Cottage Store Plants • Gifts • Books 6208 Phinney • Seattle The Herbfarm NURSERY GIFT SHOP GARDENS RESTAURANT PHONE ORDERS 800-866-HERB J Arthur P. Dome has been interested in growing and photographing various ericaceous plants for many years. He belongs to most horticultural organizations that involve these plants. Art is a member of The Arbo- retum Foundation. Sources Most specialty nurseries and garden stores carry many of these plants or can get them for you. Also, contact: Heather Acres, Inc., 62 Elma-Monte Road, Elma, Washington 98541 Howlands Heathers, 17479 Highway 99 East, Hub- bard, Oregon 97023 Wilson’s Nursery, 6227 Hopedale Road, Sardis, British Columbia V2R 1B3 Canada 4 Washington Park Arboretum Bulletin An Answer to Autumn: Leaf Compost and Mulch by Madelon Bolling ost people associate composting with veg- etable gardens, but leaf mold or compost can be used to feed shrubs and trees, as well. Some of the peat moss and manure we usually buy can be replaced by autumn’s unappreciated bounty: leaves. Leaves contain many important minerals, but they are most valuable for their role as humus in the soil. Making Leaf Mold To make leaf mold (a kind of leaves-only com- post), simply corral fallen leaves in a compost bin or other enclosure to keep winds from scattering them. Make sure that they are thoroughly damp, and let stand over winter. As in all composting, the optimum dampness is that of a squeezed-out sponge. In warm, dry weather — or if your leaf pile is in a sunny spot — cover it to help hold the mois- ture in. Shred leaves when they are dry to reduce their volume and speed up the process of decomposi- tion. If you don't have access to a shredder, a rotary mower will do very well. Make a low mound of leaves near a wall or solid fence to catch the shreddings, then run the mower back and forth over the mound until no whole leaves are left. Repeat until all the leaves are shredded. Sprinkle the shredded leaves with water as you add them to the compost bin so that the whole pile is thor- oughly damp but not soggy. If rains have dam- pened the leaves already, there is little to do but pile them up and wait, since most mowers and shredders cannot handle matted, wet leaves. If you do not shred your leaves, those on the top and sides of the pile may not decompose by spring. No matter, these may be used as mulch, or they can become part of the spring compost, which of- ten needs just such a high-carbon material to balance the high nitrogen content of fresh grass clippings. What about Those “Problem” Materials? There are leaves with bad reputations among gardeners. Some deserve them and some do not. For example, English laurel, rhododendron, and madrona leaves — and even conifer needles — will break down very well in time, especially if you can shred them up first and then keep them damp. The prickly leaves of holly and some junipers also take a very long time to break down, and make mixed compost unpleasant to handle. They are best composted separately. It helps to shred or break up these leathery leaves or needles, moisten the pile as you build it, cover it with a sheet of plas- tic to maintain moisture, and add a nitrogen sup- plement such as manure or cottonseed meal to speed the decomposition process. People often express concern about the toxicity of leaves — rhododendron, in particular. Yes, rho- dodendron leaves are toxic. So are the leaves of peach, English laurel, oleander, pieris, etc. — if you eat them! These toxic leaves break dowrn very nicely into the soil and. once composted, are not harmful to other plants. Some leaves do need to be treated with caution, especially leaves of walnut, conifers, and eucalyp- tus. Most established trees and shrubs are not bothered by well-decomposed walnut or conifer leaf material, although the fresh leaves may sup- press seedlings and annuals or inhibit the growth of some susceptible species. Rather than send them away, use these materials with care. Compost them thoroughly and consult horticultural experts before applying the leaf mold around especially prized plants. Because of their growth-suppressing character- istics, cedar or other coniferous woodchips and leaves or needles work well for pathways. An 8—12 layer will compact and eventually decom- Vol. 54: 3/Fall 1991 5 Courtesy Seattle Tilth pose into a material that is safe to use, even on veg- etables. You may want to check its pH (to deter- mine soil acidity), as this decomposed mulch may be acidic, but garden plants are less dependent upon a specific pH in the soil when there is an abundant supply of humus. Meanwhile, mulch on your garden paths will suppress weeds and keep pedestrians' feet clean and nearly dry in wet weather. Using Mulch Leaf mold, compost, or chipped-up deciduous tree branches, fruit-tree prunings, and shrub thin- nings make an excellent mulch. Even pine cones may be run through a shredder to make a pleasant uniform mulch with all the same uses as commer- cial bark products. Diseased materials should not be used for mulch. The best way to deal with these is to burn them, if possible. In some areas, such as King and Snohomish counties, it is possible to send them to large-scale composting plants that compost these and all yard wastes at high temperatures for suffi- cient lengths of time to kill disease organisms. Ideally, fallen or rotting fruit should be buried to feed the soil directly. Or you may compost it if you can build a “hot' ' compost pile that won't attract rodents to your bins. A hot compost pile requires careful construction: equal parts of fallen leaves and fresh green grass clippings, for example, pro- duce the ideal carbon to nitrogen ratio of 30 to 1. Large leaves may need to be shredded to encourage uniform bacterial activity. There also needs to be sufficient aeration and moisture throughout the pile, and a minimum size of one cubic yard. It is es- sential to turn this type of compost for aeration and mixing (always checking for sufficient moisture), as soon as temperatures pass their peak. Only three turnings — one every three or four days dur- ing the first two weeks — are usually necessary be- fore a “rough" ' compost is produced in which crit- ical materials such as fallen fruit are no longer rec- ognizable. Further turning and curing will pro- duce a more finished product, though little or no more heat will be manifest. Established shrubs will benefit from an annual feeding of a half bushel (about a 5 -gallon bucket) of compost wrorked into surface soil, and mulching from six inches away from the root crown to just past the drip line. Shallow-rooted shrubs, such as rhododendron and azalea, should be mulched very sparingly (no more than one inch deep) with com- post, but not cultivated, to avoid root damage. To feed trees, start about two feet away from the trunk, cultivate shallowly to a foot beyond the drip line, and rake an inch or two of compost into the top two inches of soil. Or, auger holes a foot deep at even intervals around the drip line and pack with finished compost. Fruit trees will benefit from three or four inches of compost raked in as above, followed by heavy mulching to well past the drip line. As it rots, the mulch will continue to feed the tree, meanwhile regulating soil temperature, conserving moisture, discouraging weeds, promoting good soil texture, and favoring increased populations of beneficial soil organisms. In the natural course of events, leaves, dead twigs, fruit, and branches fall from trees and re- turn to the soil. We disturb this cycle by pruning, raking, and then sending these materials away. By composting and mulching our own tree by-prod- ucts, we can keep our yards and ourselves health- ier and in harmony with natural patterns. Madelon Bolling works for Seattle's Community Composting Education Program as the Compost Hot- line operator. She edited Arthur Lee Jacobson’s Trees of Seattle and writes a column on composting for the Seat- tle Tilth Newsletter. Call for Composting Information: Seattle city limits: 633-0224 King County (outside of Seattle): 296-4466 Kitsap County: 876-7157 Pierce County: 59T3678 Snohomish County: 388-3425 Thurston County: 786-5441 Whatcom County: 676-6736 Elsewhere, please contact the cooperative extension service for your county. 6 Washington Park Arboretum Bulletin Can Birds Tell the Difference between Native Introduced Conifers in the Arboretum? by P. Dee Boersma and Kama N. Almasi The scientific literature is filled with examples showing that the types and structures of vegetation in a habitat often indicate the types of birds that will be present there and in what num- bers (MacArthur and MacArthur 1961). It is not surprising that birds are closely attuned to vegetation. They eat the seeds, fruits, and nec- tar that the plants produce and the insects that feed on plants. They use the plants for protection against the elements, as refuges against predators, and as sites for nests. In our study, we looked at what happened to birds when (1) landscape was al- tered by the type of trees planted, and (2) the structure and size of the trees stayed the same. We also wanted to knowr if birds can tell the difference between native and introduced conifers. Conifers are the dominant tree species in the Pacific Northwest. Since native birds in the Northwest live among conifers, we expected that native birds might prefer native conifers. On the other hand, we wanted to know if one conifer looks like any other to a bird. To examine these questions, we studied four plots of trees in the Washington Park Arboretum where native and introduced conifers grow in patches near each other (Table 1). Two of these plots had native conifers: Douglas-fir ( Pseudo - tsuga menziesii ), western red cedar ( Thuja plicata ), and western hemlock ( Tsuga hetero- phylla). The two other plots had conifers from Asia and Europe, primarily true cedars (e.g., Cedrus libani , C. deodar a, C. atlanticd) and true fir {Abies x insignis), as well as coniferous trees from Oregon and California (e.g., the giant sequoia, Se- quoiadendron gigantea , and Port Orford cedar, Chamaecyparis lawsoniana). The native plots were 1,026 m2 and 1,504 m2 in size; the plots containing introduced conifers were 1036 m2 and 1664 m2. The four plots had trees of a similar range of heights (7.5 to more than 30 meters = 25-100 feet), spacing (each plot between 21 and 27 trees), and understory coverage. For the study, we compared each native plot with a plot having introduced conifers. One native plot was approximately 35 feet from the Graham Visitors Center; the corresponding plot of intro- ^ duced conifers was mile southwest of the Visi- tors Center, bordering a residential area. The sec- ond native and introduced conifer plots to be com- pared were adjacent to each other, approximately Va mile from the Visitors Center, off Arboretum Drive East. All four plots were about the same distance from roads and water and appeared to be visited about equally by people and pets; all plots were within a mile of each other, so that a bird could easily visit all of them. If birds had a prefer- ence, we expected to see it by finding them more often in one type of conifer plot than the other. A census of each plot was taken from a location where all the birds in the plot could be viewed at once. In the winter, on five different days for ten minutes each, two observers identified all the birds seen or heard in each plot. In the spring, all the birds in the plots were counted in the morning on four different days and on four different days in the afternoon in the same manner. We found that 15 bird species from 11 families used the plots in the winter. Nine of the species were found both in the native and introduced co- nifers (Table 1). The crow ( Corvus brack yrhyn- chos ), golden-crowned kinglet ( Regains satrapa ), and red-breasted nuthatch (Sitta canadensis ) visited all the plots. Found exclusively in the native conifer plots were three native bird species, including Bewick's wren ( Thryomanes bewickii ), bushtit ( Psaltri - parus minimus ), and sharp-shinned hawk {Acci- piter striatus ), and two introduced species, includ- ing the starling ( Sturnus vulgaris) and house spar- row ( Passer domesticus). The starling and house sparrow may have been in these conifer plots be- cause one was closer to the main building in the Arboretum where there are bird feeders. The av- erage number of bird species per single observa- Vol. 54: 3/Fall 1991 7 Table 1. Lists of native and introduced bird species sited in both native and introduced conifers dur- ing a study in the Washington Park Arboretum, winter/spring 1990-91. Plot Conifers (# of trees) Winter Birds Spring Birds Native 1 Douglas-fir (9) American crow American crow western hemlock (3) American robin American robin western red cedar (6) Bewick’s wren band-tailed pigeon black-capped chickadee barn swallow bushtit black-capped chickadee 4 p- European starling golden-crowned kinglet bushtit cliff swallow house sparrow European starling / Oregon junco gold-crowned kinglet Bush tit red-breasted nuthatch house sparrow sharp-shinned hawk Oregon junco rufous-sided towhee song sparrow Native 2 Douglas-fir (7) American crow American crow western hemlock (6) American goldfinch American goldfinch western red cedar (7) American robin American robin black-capped chickadee band-tailed pigeon European starling black-capped chickadee gold-crowned kinglet cliff swallow ri'T • ■ .*.■ house sparrow flycatcher red-breasted nuthatch gold-crowned kinglet Townsend’s warbler great blue heron varied thrush house finch So ^7 sparrow v^'V. * — . \ house sparrow Oregon junco purple finch ruby-crowned kinglet V- rufous-sided towhee . * ■ # « r* V Goldfinch song sparrow western tananger V 4 unidentified species Introduced 1 Atlas cedar (3) American crow American crow Cedar of Lebanon (7) American goldfinch cliff swallow Coulter pine (2) gold-crested kinglet European starling Deodor cedar (2) Oregon junco house sparrow true fir (3) red-breasted nuthatch red-breasted sapsucker red-breasted nuthatch Introduced 2 Cedar of Lebanon (1) American crow American crow Colorado spruce (6) American goldfinch American robin Cyprus/cedar (1) American robin barn swallow Giant sequoia (5) black-capped chickadee brown-headed cowbird Port Orford cedar (10) gold-crowned kinglet cliff swallow silver fir (1) red-breasted nuthatch house finch Taiwania cryptomerioides (2) varied thrush rufous-sided towhee Illustrations by Fred Sharpe , published with permission of the Seattle Depanmen t of Parks a) id Recreation 8 Washington Park Arboretum Bulletin tion in the native sites (4 species) was significantly greater than in the introduced conifers (2 species). In spring 1991, we also saw more bird species in the native plots during each observation. Twenty-four bird species occurred in the native conifers and only ten in the introduced conifers. Crows, cliff swallows ( Petrochelidon pyrrbonota ) and three introduced species (the starling, house sparrow, and house finch [i Carpodacus mexicanus ]) were found in both native and introduced plots. The junco (Junco hy emails), golden-crowned kinglet, song sparrow ( Melospiza melodia ), band- tailed pigeon ( Columba fasciata ), and black-capped chickadee ( Parus atricapillus ) were seen only in the native tree plots. All bird species found in both of the introduced conifer plots also were found in native conifer areas. The average num- ber of bird species per single observation in the na- tive sites (5 species) again was significantly greater than in the introduced sites (2 species). C.A. Gavareski (1976), a graduate student in forestry, found that changing the vegetation in the Washington Park Arboretum resulted in the de- cline of native bird species; the species most nega- tively affected were the bushtit, red-breasted nut- hatch, and Bewick’s wren. Birds were counted if they landed on areas only briefly, so sites with in- troduced conifers may appear to have more active birdlife than is the case. Several native species, however, were seen only in the native conifers, showing how important the native trees are to these birds. There has been a rapid decline in native, undis- turbed coniferous vegetation in the Pacific North- west. Considering the importance of this vegeta- tion to our native birds, native conifers should be planted where replanting is done; it is important for providing food and refuge for native bird species. When picking plants for the yard, choosing na- tive species may be one way to help native birds survive in their increasingly urbanized and frag- mented environment. The trees you plant affect the Bewick's wren, bushtit, kinglet, junco, chick- adee, and song sparrow. Conserving our native vegetation is one of our best lines of defense in protecting our native wildlife. Birds can tell the difference. Acknowledgment We thank Linda Ward for helping with the win- ter counts in the native and introduced plots, and for her contribution to the intellectual develop- ment of this project. P. Dee Boersma is a professor in the Institute for En- vironmental Studies and Department of Zoology, Uni- versity of Washington. Dr. Boersma is well known for her work on Magellanic penguins. Kama N. Almasi received a B.A. in Asian studies from Connecticut College. She was a fifth-year student at University of Washington, taking science courses. In fall 1991, she started graduate work at University of California. Davis. This paper is an outgrowth of a pres- entation with Linda Ward in Dr. Boersma’ s conserva- tion biology class. References Gavareski, C.A. 1976. “Relation of Park Size and Vegetation to Urban Bird Populations in Seattle, Wash- ington." Condor 78: 375-382. MacArthur, R.H., and MacArthur, J.W. 1961. “On Bird Species Diversity." Ecology 42: 594-598. Further Information Checklist of Birds, Washington Park Arbore- tum/Lake Washington Montlake Fill/Union Bay Marsh. July 1987. Compiled by Merilyn Hatheway, Phil Mattocks, and Dennis Paulson. Arboretum Waterfront Self-Guided Trail. 1986. Seattle Department of Parks and Recreation. Vol. 54: 3/ Fall 1991 9 Coats of Many Colors by Daniel J. Hinkley A color photo essay of ornamental barks in the Arboretum follows this article. An asterisk (*) indicates species, including varieties and/or forms, that can be found in the Washington Park Arboretum. The outer layer of shrubs and trees plays sec- ond fiddle to the attention paid to foliage, flower, and fruit in the garden. A pity, it seems, as it is the skin of these plants that is with us the full calendar, in contrast to their more ephemeral at- tributes. Ghostly white, sensually smooth and bronze, brilliant reds and yellows, and patchwork quiltings of red, gray, green, and brown all can describe the varieties of interest provided by the bark of many woody plants. Bark can be a tactile ornament, meant for strok- ing and polishing with our hands as we walk our gardens, or for marveling at with its bright con- trasting colors during the winter months. It also can be a focal point in the garden year-round, as with the smooth and gray pachydermic monoliths of the European beech. In Trees and Shrubs Hardy in the British Isles , W.J. Bean did not mention the beauty of bark on several of the species included below. Perhaps these special effects had not yet begun to develop in many of the specimens he had observed. Or, is it that even among the more astute plantspeople, bark is often neglected as worthy ornament for our gardens? How Bark Develops The cambium of woody plants, located just un- der the bark, is the tissue that is responsible for growth in diameter. Each spring as growth re- sumes, millions of cells comprising this cambium layer are replicated through cell division. Those new cells that form inside of the cambium become the xylem, the tissue that draws water and nutri- ents from the soil and pumps them to the leafy su- perstructure of the plant above. Sister cells also form on the outside of this tissue and become the phloem — “pipework” to distribute simple sugars produced in the leaves of the plant through photo- synthesis. Phloem and xylem cells usually function for a few years at most; older generations of cells cease to function in their original capacity but the plant has not yet lost interest in their existence. More often than not, one or more layers of corky tissue, impregnated with waxes, form in the outermost aging phloem that will protect the fragile cam- bium layer only millimeters within. Suberin, a common ‘ ‘filler' ' of these dead cells, is present in the highly pliable, yet tough and waterproof, stop- per of fermented libations. The cork of commerce is actually dead suberin-filled cells harvested from Quercus suber , the cork oak. Ultimately, these ag- ing cells, continually replenished from behind the ranks, are expelled from the tree. It is the last hur- rah of these sloughed cells — the bark — that pro- vides garden interest to the horticulturist. The fol- lowing species of plants represent a small percent- age of those that can be grown for the effects of bark alone. Three Rubus Species with Exceptional Bark The white-stemmed brambles of the genus Rubus generally are absent from the gardens of the Northwest. It requires some effort to keep them in bounds, though by no means is impossi- ble since many European gardeners have utilized them effectively in their gardens for years. Three Glossary Cambium is the plant tissue responsible for growth in diameter, found in between the phloem and xylem. Coppice refers to periodic and severe prun- ing as a means to rejuvenate young, vigorous growth. Glaucous is the blue or white coloration pro- vided by a thin coating of wax found on leaves or stems. Gymnosperm, literally “naked seeds," are one of the more primitive components of the plant kingdom comprising the conifers, among others. Panicle is a branched flower cluster. Phloem is the tissue responsible for trans- location throughout the plant of sugars that have been produced by photosynthesis. Photosynthesis is the process of food manu- facturing within a plant. Suberin is a waxy material found in the cell walls of cork tissue. Sucker is to send out shoots from the root or lower part of the stem of the plant. Xylem is wood; a plant tissue which conducts water and minerals. 10 Washington Park Arboretum Bulletin species of this genus, all from China, stand out as being top notch with their shining white, albeit thorny, stems during winter months. Rubus cockburnianus is a medium-sized shrub with finely cut foliage and stems that emerge fresh each year a lime green. As the summer pro- gresses, a thicker glaucous coating is laid down and by winter the stems are white as December hoarfrost. More vigorous in growth is * * Rubus biflorus var. quinqueflorus which produces a many-stemmed shrub to fifteen feet in height. The winter canes are as brilliant, if not more so, than R. cockburnianus , though on an altogether larger scale. Recently introduced from China by the Arnold Arboretum is yet another species, R. lasiostylus var. hubeiensis , perhaps the most strik- ing and attractive of this trio. The bark of this species is intensely white and coated with a multi- tude of tiny hairline bristles quite unlike the vi- cious thorns we are all too familiar with in this genus. This species provides an intensely colored, yet finely textured, effect and could be used in back of a smaller border. All Rubus species will sucker from the base, so precautions should be taken to either contain them or simply allow them ample room. They should be coppiced to the ground each year for two reasons. First, the canes lose their intensity after one season, fading to a dull pearlish white. Second, these species bloom and bear fruit on sec- ond-year wood, and it is prudent to prohibit them from doing so lest they escape your garden via visiting birds and contaminate our native flora with yet another unwelcome introduced species. The Bark of Dogwood The red-twig dogwoods in the genus *Cornus have long been grown for the intensely red or yel- low bark in winter, their primary season of inter- est. *Cornus alba ‘Elegantissima’ performs back to back with its bright red winter stems giving way in spring to gray-green leaves neatly mar- gined with white. In the Washington Park Arbo- retum, it can be found between Azalea Way and Lake Washington Boulevard, near the flats. The bark of *Cornus alba ‘KesselringiF (also near the flats) is remarkably dark red, approaching black- purple. The foliage of this cultivar is dark green and as a whole rather nondescript during the sum- mer months. However, during winter a massing of this shrub, combined with the yellow twig dog- wood, *Cornus stolonifera ‘Flaviramea’ for con- trasting color, is a bold yet refined composition. UNCOMMONLY BEAUTIFUL WellsAVedina N U R S E R Y 8300 Northeast 24th Street. Bellevue 454 1853 The newly introduced yellow twig dogwood cul- tivar, Cornus alba ‘Silver and Gold’, has bright yellow stems in winter with white variegated sum- mer leaves. Every third year these species of dog- wood will benefit greatly from being cut to the ground in early spring in order to stimulate new growth and intensify color during the winter months. Mottled Persian Ironwood *Parrotia persica , the Persian ironwood, is of- ten thought of as a small tree or large shrub whose main offering of ornament is autumn coloration of intense oranges and reds. This witch-hazel rela- tive. however, also develops beautifully mottled bark in flaking patches of green, gray, and brown as the plant matures. It is interesting to note that in its native haunts of northern Iran, P. persica grows so thickly that its branches self-graft to ad- jacent specimens, making impenetrable fences that extend for miles. A fine specimen of P per- sica can be observed in the Hamamelidaceae col- lection adjacent to Arboretum Drive East. Interesting Effects of the Elm Family The elm family, Ulmaceae, is not considered by most as a group of plants that provides interesting VoE 54: 3/Fall 1991 11 effects from its bark. However, there are at least three that are quite beautiful in this respect and worthy of mention. Zelkova sinica , a little known or grown species, provides an outstanding patchwork effect of bark in greens and browns. This species is a medium- sized shade tree of strong wood, graceful habit, and — as with its more common cousin, *Z. ser- rata — good autumn coloration. It is not in the col- lections of the Washington Park Arboretum, though I successfully germinated seeds of this species last spring. Zelkova sinica should be con- sidered a desirable tree for our landscapes, of multi-purpose and possessing year-round interest. More frequently encountered, though not com- mon in landscapes and city streets, is * Ulmus par- vifolia , the Chinese elm. Unfortunately, its rela- tive, the greatly inferior * Ulmus pumila (the Si- berian elm), also has been dubbed the Chinese elm. The true Chinese elm is a small tree possess- ing small glossy green leaves held on a rounded crown. A flaky brown mottled trunk provides beauty year around. Ulmus parvifolia , resistant to the Dutch elm disease, is an excellent choice for the small patio or garden. Pteroceltis tatarinovii is yet another member of Ulmaceae that is rare in both collections and in commerce, yet available if sought. Roy Lancaster, noted English plantsman, describes its mottled bark as rivaling *Stewartia pseudocamellia , the most beautiful of Stewartia species in this respect. Pteroceltis has small glossy green leaves that one might suspect are evergreen by their nature, yet proves to be fully deciduous in our climate. It would make a rare, yet lovely, specimen tree in a moderately sized urban landscape. More Species of Interest *Lagerstroemia species and hybrids, the crape myrtles, have been grown in the Northwest for many years, yet it is infrequent that we have a summer of significant length and warmth re- quired to produce flowers. No matter, as it is the bark of this tree that brings us a much longer and more substantive season of interest. Many cul- tivars and hybrids exist and each brings a different effect with its bark of crisped flaky red, mottled greens, or olive and gray. There is a specimen on the south side of the Center for Urban Horticul- ture and several hybrids along Azalea Way in the Arboretum. One well-known specimen is located in the Medicinal Herb garden on the University of Washington campus. Placed adjacent to the path, its bark is polished and oiled on a daily basis by the hands of visitors as they pass by. Proof enough that some bark is tactilely pleasing as well as beautiful from afar. For forty years, *Persea yunnanensis , the “hardy” avocado, has grown along the upper trail just north of the Peony collection, across from the Legume section of the Arboretum. Na- tive to southwestern China, this specimen was raised here from seeds received from China through the Arnold Arboretum in 1938. Per sea americana is the common edible avocado of com- merce that is hardy only in semi-tropical areas. In my estimation, Persea yunnanensis is one of the most overlooked broad-leaved evergreen trees in the collection. It produces a small tree to 30 feet with white flowers produced in loose panicles in summer. Shiny linear leaves to four inches remain on the tree year-round. Best of all is its highly textural black skin reminiscent of tanned alligator hide (from a time when it was not considered eco- logically inappropriate fashion). The specimen in the Arboretum has consistently provided fruit for local growers to collect and grow, and it is fre- quently encountered in local nurseries and plant sales. Consider this hardy and tidy species as a small tree for foundation plantings or as an ever- green hedge. *Pseudocydonia sinensis is a rare relative of the common edible quince, Cydonia oblonga , as well as the flowering quince, * Chaenomeles speciosa. Pseudocydonia , native to China, is a rounded tree to 20 feet in height. White pear-like blossoms are produced in early spring followed by very large oblong fruit that is much like quince — hard as a rock, even upon ripening. The interest of this tree is the beautiful mottled bark which takes on shades of white, gray, green, and brown. I first en- countered it while in Japan and marveled at how intensely beautiful the bark was. Later, I dis- covered that several are growing in Seattle, includ- ing an exemplary specimen south of the Botany Greenhouses at the University of Washington, ad- jacent to the windmill palms ( Trachycarpus for- tunei). This is an outstanding diminutive tree that deserves more attention as a multi-seasonal plant for the small landscape. To ignore the birches in an article on bark is truly sacrilegious. With their beauty comes pit- falls and detriments, yet to avoid these trees be- cause of their susceptibility to aphids is an unfor- tunate attitude of many people. Their propensity of hosting these insect pests is forgiven when one 12 Washington Park Arboretum Bulletin realizes the pests themselves provide an abundance of food to many bird species in our area. Bushtits, chickadees, and yellow- and red-crowned kinglets all eagerly feast on the grazing, yet undamaging, pestilence associated with these trees. It is not a question of whether or not to plant a birch species, but where it should be placed in the landscape. Wise placement is away from underlying objects that may inherit the sticky rain caused by these “critters.” * Betula pendula, the common European birch, has been panned by landscape designers who are currently planting thousands of the Himalayan * Betula jacquemontii. It dons brilliant and nearly flawless chalky white bark, making one suspicious that they have in fact been recently painted. The most lovely and deserving of planting in our land- scapes is another infrequently encountered Hima- layan species, *B. albo-sinensis var. septen- trionalis. Smooth glossy pink and silver bands cover the trunk and older branches. One of the true delights of being a horticultural educator is being able to show this species to students and witness their marvel and fascination at a plant so unjustifiably scarce in our area. The flowering plants do not hold a monopoly on cuticular interest as many gymnosperms ex- hibit bark of extraordinary beauty. Though many species of pines are known for lovely platy bark, the best of the lot is perhaps *Pinus bungeana from China. Though one must wait for the effect, which could be some time, the bark develops into a dazzling patchwork of white, grey, brown, and green as the plant matures. Few species of plants, tropical or temperate, could rival this pine for the patchwork effect alone. Often found in or near temple gardens of China, they are seldom seen in the Puget Sound region. The Arboretum hosts one specimen and an 8' tree was recently planted on the south end of Sieg Hall at the University of Washington. Taxus brevifolia, the Pacific yew, is native to the Puget basin and currently harvested as a source for taxol, an effective treatment for ad- vanced cancers. Though the innards of this tree have been exhaustively studied and reported, the fact that it possesses extraordinarily beautiful bark is seldom mentioned. Flaky patches of green, grey, and red provide a finely textured and color- ful framework for the evergreen needles that spring from its branches. See the cover story in the winter 1991 issue (53:4) of the Bulletin. As landscape designers, horticulturists, and garden enthusiasts, we choose plants for the land- scape for many reasons. Autumn color, floral beauty, fragrance, and showy fruit are more often than not the criteria for selection. Let us not fail to consider the scaffolding that bears these attri- butes. The interest provided by bark is a treasure that can be enjoyed twelve months of the year. Daniel J. Hinkley, once and future editorial board member, is a horticulture instructor at Edmonds Com- munity College. Dan owns and operates Heronswood Nursery, specializing in unusual and difficult-to-locate trees, shrubs, vines, and perennials. INTERIOR DESIGN Residential - Executive Offices Courtyards and Tea Gardens PROFESSIONAL MEMBER AMERICAN SOCIETY OF INTERIOR DESIGNERS (206) 525-2207 SEATTLE, WA Arboretum Foundation member, 40 years Vol. 54: 3/Fall 1991 13 Ornamental Bark in the Washington Park Arboretum Upper, left to right: Betula albo-sinensis Taxodium distichum (bald cypress) Firms ponderosa (Ponderosa pine) Betula platyphylla (Asian white birch) . Lower, left to right: Acer refinerve Acer griseum (paperbark maple) Firms resinosa (red pine) . Photos by Joy Spurr (. Pinus resinosa by Daniel J. Hinklev) Vol. 54: 3/Fall 1991 Quercus sadleriana grows 6-8 ' tall and has the largest evergreen oak leaves. Here, under a Douglas-fir, it is combined with Viburnum carlesii , with the fern Polysticbum munitum and Galax urceolata below it. Evergreen Oaks for Northwest Gardens by Mareen Kruckeberg Photos by Joy Spurr Evergreen oaks are grown for beautiful foliage that has variation in color ; texture , size , and shape. An asterisk (*) indicates species, including varieties and/or forms, that can be found in the Washington Park Arboretum. Tears ago when my husband Art and I were busy acquiring new plants for the garden, our quest for natives did not go far beyond the Pacific Northwest. However, one intrepid collec- tor and friend was willing to go much farther afield, and he was very successful. His botanizing took him to the Southwest — from California east to Arizona and New Mexico. The introductions he brought back have enriched our gardens im- measurably. The evergreen oaks of the Southwest were a part of these collections. Not only did this collector gather the seed of evergreen oaks, but he germinated and grew these unusual trees and shrubs of the desert states. He found they acclimated quite well. The collector’s 16 Washington Park Arboretum Bulletin Glossary Entire leaves have no teeth or lobing; they are smooth. Intemode is the part between two nodes of a stem. Lanceolate leaves are shaped like a lance head. Obovate leaves have tips larger than the base. Rugose (wrinkled) means that the veins are sunken and the spaces between are elevated in the leaves. Scurf is scale. name was Carl S. English, Jr., and his show place was, and is, the Hiram M. Chittenden Locks in Seattle’s Ballard district. Many of our original plants are from his collections. People who visit our garden in Richmond Beach, north of Seattle, are always attracted to the evergreen oaks. Very often they are astonished that the tree or shrub that intrigued them is, in fact, an oak. It is not like any oak they are familiar with, as many look more like holly. But as the plants mature and produce the familiar acorn, there is indisputable proof. We grow many different species of these oaks for their beautiful foliage. From May into August, the new growth can be as showy and attractive as flowers, with colors ranging from bright red to fuz- zy pink, and soft gray-green to tawny yellow. The size of the leaves ranges from the tiny Quercus dumosa (at less than one inch) to *Q. sadleriana , the largest at 1" long. Some evergreen oak leaves are heavily veined, and their textures vary from rugose to shiny and smooth. Many garden plants are grown for their spectac- ular show of beauty while flowering, and they are a great joy for that brief time, but offer little to the landscape design for the rest of the year. Foliage plants provide a quieter beauty, but for a much longer period. The evergreen oaks, in particular, provide a variation from the other broad-leaved evergreens in the garden such as rhododendrons, viburnums, and cotoneasters, which often are over used. Growing Evergreen Oaks Most evergreen oaks like sun, but some prefer shade. They all require excellent drainage. Stand- ing water in the root zone means death. This can be a hidden danger, as you might not be aware of hardpan 3 feet down; when water reaches it, it can- not penetrate and so spreads out. The roots of the oak are forced to do the same, thus being drenched for long periods. A bad combination is a specimen evergreen oak and a lawn. The lawn needs much more water than the oak can handle. Planting on a slope is one solution; another is to plant in the root zone of a large tree. The tree roots tend to be greedy and will take up the excess water. Except for this root-rot problem, which mostly can be avoided, our plants have been free of any disease. We have had no noticeable damage by insects. Many Species for Northwest Gardens My favorite evergreen oak is a native, * Quercus sadleriana , from the Siskiyou Mountains in southern Oregon. It has deep yellow-green leaves that are prominently veined, large, and really quite spectacular — especially as they expand in early spring. Quercus sadleriana is an understory plant in its native setting and grows 6-8' tall; it also will get this wide, if given the space. Give it partial or Quercus myrsinifolia is in the Japanese Garden of the Washington Park Arboretum. The netleaf oak, Quercus reticulata , has showy veins. afternoon shade. We use three specimens as fea- ture plants under a large * Douglas-fir, and have a bed of Cyclamen hederifolium under the same canopy. The cyclamen has large green leaves that are marbled silver and white, and rose pink flowers in late summer. It likes the same conditions as the Q. sadleriana. * Quercus vacciniifolia , the huckleberry oak, is found on high slopes and ridges of the Siskiyous and Sierra Nevadas. It is a shrub up to 4' tall, with small, oval, mostly entire leaves, covered beneath with pale gray scurf. This tree is slow growing and variable, but a delight in a dry sunny spot. * Quercus chrysolepis has a wider range, from southwest Oregon into California, Arizona, and New Mexico. Also known as canyon live oak or maul oak, it has holly-like juvenile foliage, becom- ing entire in older trees. There is a great deal of variation in size and shape, depending on the con- ditions they grow in, but the ones found in open situations form a wide-spreading tree of 30 or 40' high, with massive horizontal limbs and a short clear trunk. In a California park, one of these huge The smallest evergreen oak leaves are on Quercus dumosa. Quercus bypoleucoides leaves are white woolly beneath. limbs has become a much-used walkway for little feet; even though there is probably no danger, a nervous Parks Department felt it prudent to ade- quately prop up the irresistible detour. We have grown * Quercus agrifolia , the Califor- nia live oak, for many years, but the last three rec- ord cold winters have taken their toll. This last winter, we finally lost our twenty-year-old speci- men. Some of the younger plants are making a val- iant attempt from the roots, but it is a borderline tree for hardiness in North Seattle. In warmer areas comparable to the Arboretum or the Chit- tenden Locks, it might do very well. It is the fastest growing of any of the evergreen oaks we have; plants grow up to six feet per year. * Quercus bypoleucoides , the silverleaf oak, has done well for us. The leaves look like they’ve been waxed; they are lance shaped, thick and leathery — shiny dark green above and densely white woolly be- neath. Ours is a small tree, but it can vary from a 6 shrub to a tree 65 tall. Arboretum visitors can see this unique and ornamental species, which is from Arizona and New Mexico, close to the Graham Quercus yjlauca has yellow-green leathery leaves. Visitors Center and near Rhododendron Glen. * Quercus dumosa (found near the Japanese Garden) and Q. durata are California scrub oaks. There is very little difference between them away from their native habitats, but in the wild, Q. durata only grows on serpentine. The foliage and acorns are even more variable than tanbark oak, but it is worth growing for its tiny toothed leaves and twiggy habit. I plan to try them for bonsai be- cause of the small leaf size. The netleaf oak, * Quercus reticulata , is well worth growing. It has dark green obovate leaves with the network of veins clearly showing on the back. When spindly specimens are pruned back se- verely, they will form an attractive new compact shrub. Find specimens at the north and south ends of Azalea Way. There is a lot of variation between species as well as within a species. As an example, in north- ern California we collected acorns of * Lithocarpus densiflorus (formerly in the genus Quercus , but changed because of technical difference with flowers). Some of the progeny of the so-called tan- bark oak were very fast growing and became trees, whereas others were slow and remained shrubs. This variation is noticeable in young plants from the size of the leaves and length of the internodes, so you can judge the amount of space needed for a mature specimen. The Arboretum’s best specimens are between Azalea Way and the Lynn Street Bridge. In the landscape, Lithocarpus can be a focal point because of its large evergreen leaf that can serve as a background plant for almost anything, including deciduous trees. The new growth is fuzzy pink or tawny yellow. In addition to the shrubby form which has been named *L. densi- florus var. echinoides , there is a remarkable mu- tant, forma attenuato-dentatus , that has created a lot of interest. Exotic Species We also grow a number of exotic evergreen oaks. Three from China and Japan are * Quercus phillyreoides , *Q. myrsinifolia , and *Q. glauca. Quercus phillyreoides , grown near the north end of Azalea Way and near Arboretum Drive East, is a small tree with glossy smooth obovate leaves, usually bronze tinted when unfolding. Some years the leaves have been a bright red — very striking. Quercus myrsinifolia is a compact, densely branched, round-headed small tree. Grown in the Japanese Garden, it has yellow-green lanceolate leaves with fine tapered tips. New growth is purple-red when unfolding. Quercus glauca is also a small tree or large shrub. The yellow-green leathery leaves are oblong, coming to an abrupt point, and are much larger than the two previously named species. The water requirements of these three species are not as restrictive as our natives. They should become better known as they will make good garden plants. * Quercus ilex , the Holm oak from the Mediter- ranean region, is much better known in our area, even being used as a street tree. It will get to be large with a rounded head of branches, the tips be- coming pendulous with age. The Holm oak in our garden is beginning to show this characteristic at 30 years, becoming quite a handsome specimen. As a younger tree, however, it didn’t have the ap- peal of the other evergreen oaks and I had no qualms about using it as a support for a Clematis macropetala. There were native red cedars on either side, but they were very dense, so the more open oak was perfect for the climbing vine; it was a very successful venture. The clematis is now two- thirds up into the 40' tall canopy of the oak and puts on a spectacular display in May. Quercus calliprinos and Q. trojana , of Palestine and southeastern Italy, have survived our coldest winter, but have yet to be planted in the garden. The foliage of the young Q. trojana is especially beautiful; even though it is only semi-evergreen, it will be interesting to see it develop. There is probably no single group of plants in our garden that has brought us more pleasure each spring than the evergreen oaks. Having them sur- vive the winter is the first challenge met, and set- ting their first acorns is a thrill. But mostly it is their structural strength — balanced with the con- stant variation of foliage color and texture — that endears them to us and ensures them ever larger space in our landscape. Mareen Kruckeberg has been a member of The Arbo- retum Foundation for over thirty years. She is also a member of American Rock Garden Society and the Northwest Horticulture Society. Her MsK Nursery grows its own stock from Northwest native seeds and cuttings, and seeds from all over the world (China, Japan, Chile, Russia, the south island of New Zealand, and South Africa). Mareen’ s requirement for MsK stock is that it be hardy to this region and interesting in the garden. Joy Spurr’s photographs of plants can be seen in text- books and other publications around the world. She is a member of Unit 81 of The Arboretum Foundation. Vol. 54: 3/Fall 1991 19 'PT 0.5 m Psychotria and the Conservation of Tropical Biodiversity by Clement W. Hamilton illustrations by Karen Krager Psychotria, a plant genus, is being studied by Clement Hamilton for two reasons: to deter- mine which tropical regions need the most in- tensive conservation effort and to find out about its intriguing method of reproduction. ¥1 Xe all have heard the mind-boggling num- Ww bers and estimates. Half to two-thirds of all species of life occur in the tropics on only six percent of the earth’s land surface. One square mile of forest in northern Colombia hosts as many plant species as all of the British Isles. Twenty-five to 50 acres of tropical rain forest are being logged every minute. The human population of Kenya is doubling every 17 years, increasing pressure on the countryside. One-fourth of our pharmaceuti- cal drugs owe their origins to tropical plants and Psychotria pittieri shrub, found in Panama. animals. This biological richness is going extinct, however, before we can survey the organisms for medicinal use or even finish our basic cataloging of the species (Myers 1984; Brown et al. 1989). Just as citizens contribute to conservation or- ganizations, I feel an obligation to dedicate a sub- stantial portion of my research effort to biological conservation in general and to tropical conserva- tion in particular — a “tithing” for biodiversity, if you will. Since 1981, I have conducted research on a little-known genus, Psychotria , which is in the coffee family (Rubiaceae). Despite its relative lack of notoriety, it is one of the most diverse in the world, comprising approximately 1,650 species of shrubs, small trees, herbs, and epiphytes in all three tropical regions of the world: Latin Amer- ica, Africa, and the Asian region. The three species in Florida are called false coffee , for their fleshy red fruit with two hemispheroidal seeds. Conservation planners who wish to plan parks and reserves to conserve the most species in the United States or Europe can refer to floras such as that of Hitchcock and Cronquist (1973), species lists, and sets of copious herbarium specimens. However, the tropics are so little known, by com- parison with temperate zones, that conservation planners do not have reliable floras and must rely heavily on knowledge of a few “indicator” groups: families and genera that are well studied 20 Wasbinpfton Park Arboretum Bulletin Glossary Biodiversity refers to numbers of species of animals and plants in a given area, and their genetic variations. Corolla consists of the petals of a flower. Epiphytes are plants that grow on other plants, but derive their moisture and nutrients from the air and rain water that has flowed down the bark (stem flow) to collect minerals. Flora is a book (or books) describing all species that occur in a particular geographic area. In heterostylous species, half of the existing plants have flowers with a long style and short stamens, and are called “pin” morphs; the other plants have a short style and long stamens, and are called “thrum” morphs. Pistil is the female organ of a flower. Stamen is the male organ of a flower, con- taining pollen. Style is the narrow part of the pistil, through which pollen tubes grow. and presumed to reflect patterns of species rich- ness of tropical organisms as a whole. Psychotria is one such index group, which is why I under- took its study in Mexico and Central America when I was a student at the Missouri Botanical Garden in St. Louis, Missouri. Psych otrui’s Reproductive Biology Psychotria not only has the potential to provide information for conservation planning, but it is simply a fascinating genus. One of the most inter- esting aspects of its biology concerns its breeding (reproductive) system. Most species are heterosty- lous, a phenomenon first studied intensively by Charles Darwin in the genus Primula. In hetero- stylous species, half of the existing plants have flowers with a long style and short stamens; this is called a “pin” flower morph. The other half of the plants have a short style and long stamens; this is called a “thrum” morph. Pollen from pin plants only can fertilize their counterparts with thrum ovules and vice versa. In other words, even though a plant contains both male and female organs, it relies on another plant for pollinization. This method of reproduction avoids inbreeding and its sometimes harmful consequences such as deleterious genes becoming common. The mech- anism ensures cross-pollination and continual ge- netic diversity within a population, so that species can evolve in changing circumstances. AjRnea nuRseRies Over 50 years of quality plants and service ,/y Since 1940 Growers and V Propagators of Choice Nursery Stock Seattle O Bellevue O Bremerton Contemporary Jewelry Design At Madison Park Fine custom design at affordable rates, from traditional to contemporary. Unique gem and diamond selection. Multi-color gold specialists. ‘Distinguished' member of the Society of North American Goldsmiths. RINGWORKS 4031 E. Madison St. 206-323-8811 Hours Tues - Sat 11:00 to 5:30 Evenings by appointment Vol. 54: 3/Fall 1991 21 The pin morph (a-c) and thrum morph (d-f) of Psych otria marqinata. Complete flowers (a,d), opened eorolla and stamens (b,e), and pistils (c,f). Some other plant species are self-incompatible and others have male and female flowers on total- ly separate plants (dioecy), so why does Psychotria have its more complicated system? So each plant can bear fruit. It is thought that some insect flower-visitors, such as butterflies, rub against long flower parts and short parts on different areas of their bodies while they probe for nectar. Then they naturally deposit thrum pollen, from the long stamens, onto the long styles of the pin flowers of different plants, and vice versa. That way pollen is directed to its proper target and all plants can bear fruit, unlike those (such as hollies) with separate male and female plants. Current research (Hamilton 1990) is providing information on the significance of heterostylous plants: why their reproductive mechanisms have evolved this way, what this means to their ecol- ogy, and its significance to their conservation. This will help us understand what size population is necessary to conserve a species, for instance. Biogeography, Conservation, and Psychotria Taxonomic research on Psychotria subgenus Psychotria in Mexico and Central America re- vealed the presence of 61 species, three of them divided into varieties. Fifteen of those species I de- scribed for the first time as being new to science. It is typical for tropical researchers to find 25 per- cent new species in any group studied, which fur- ther illustrates the paltriness of our knowledge of tropical diversity. Of significance to conservationists, an interest- ing geographic pattern emerged. The greatest di- versity occurs in Panama, which has 40 species, including 1 5 restricted (endemic) to the country. That diversity drops somewhat in Costa Rica, which is still relatively rich, and then plummets in Nicaragua, Honduras, and El Salvador, which have several species but no endemics. A secondary cen- ter of diversity appears in southern Mexico, Guate- mala, and Belize. This general pattern is consistent with that found in other recently studied groups, such as Anthurium (Hamilton 1989). These findings give a clear message to govern- ment agencies and conservation planners. In order to maintain carbon balance and not disrupt present patterns of temperature and precipitation, all forests are important. But for the preservation of biodiversity, a dollar spent conserving Panama- nian forest — with more diverse native plant species — is much better spent than in Honduras, for instance. Armed with data such as that in Psy- chotria, agencies can make strong appeals to local governments, as well, in hopes they can all manage their natural heritage as well as Costa Rica is now demonstrating. This is certainly an uphill battle, and there is much cause for pessimism. But the often quoted line of Edmund Burke bears repeating: “Nobody makes a greater mistake than he who did nothing because he could do only a little. Clement W. Hamilton is associate professor of horti- cultural taxonomy at the Center for Urban Horticul- ture, University of Washington, where he curates the Hyde Hortorium. He also serves on the board of direc- tors of the Organization for Tropical Studies, Costa Rica, of which the University of Washington is a mem- ber institution. References Brown, L.R., et al. 1989. State of the World 1989- New York: W.W. Norton & Co. Hamilton, C.W. 1989. “A Revision of Mesoameri- can Psychotria subgenus Psychotria (Rubiaceae). An- nals of the Missouri Botanical Garden 76: 67-111; 386-429; 886-916. Hamilton, C.W. 1990. “Variations on a Distylous Theme in Mesoamerican Psychotria subgenus Psycho- tria (Rubiaceae). Memoirs of the New York Botanic Garden 55: 62-75. Hitchcock, C.L, and A. Cronquist. 1973. Flora of the Pacific Northwest: An Illustrated Manual. Seattle: University of Washington Press. Myers, N. 1984. The Primary Source: Tropical For- ests and Our Future. New York: W.W. Norton & Co. 22 Wasbirufton Park Arboretum Bulletin In the Washington Park Arboretum by Timothy Hohn and Christina Pfeiffer Trail work with students from the Seattle Public Schools Work Program, supervised by Cathy Breummer, Arboretum staff. Training for High School Students his past summer, the Arboretum horticul- ture staff provided training for a group of 10 high-school age students enrolled in the Seat- tle Public Schools Work Training Program. The students, accompanied by two teachers and Arbo- retum staff, implemented some much needed ren- ovation work on the Memorial Hillside (near where Loderi Valley intersects Azalea Way). In addition to weed control and mulching, the group rebuilt several paths and stairways to improve the access to this interesting area. The students, with additional help from a University of Washington student in landscape architecture, developed new skills in gardening and landscape construction during the course of this project. It was a very suc- cessful endeavor. The Arboretum Hires a Field Arborist On August 19, a new era of tree care began in the Arboretum with the hiring of Lou Stubecki, field arborist. Lou comes to us from the Davey Tree Expert Company with an undergraduate de- gree in forestry from Syracuse University. With the generous support of the Arboretum Founda- tion, Lou will be responsible for a complete range of tree care in the Arboretum, from the sapling stage to mature trees. He will be handling all ground-based tree care activities personally and managing contractors to accomplish the tree crown work. Immediate needs will focus on the damaged and hazardous trees remaining from the storms of December 1990. Three New Projects Three very exciting projects have moved out of the planning stage and are now under review: (1) the plant collections display master plan for the en- tire Arboretum; (2) the program and concept state- ment for the renovation of Azalea Way; and (3) the program and concept statement for a synoptic gar- den at the Graham Visitors Center. The synoptic garden would provide a sample of the Arboretum collections. These projects are part of an Arbore- tum renaissance for the twenty-first century. More on these projects in upcoming columns. Plants Collected from Chile As a sponsor of a plant collecting trip to Chile conducted by personnel from the Arnold Arbore- tum, the Washington Park Arboretum received many interesting wild-collected accessions from this region. Many of these plants have been ac- quired at one time or another in the past; how- ever. these collections represent new provenances and slightly different gene pools. We will watch them closely to document their growth and adapt- ability here in Seattle. Recent New Accessions 105-91 Arbutus ‘Marina* (Ericaceae): the product of a three-way hybrid selection of Ar- butus taxa from the Mediterranean region and the Canary Islands. We received this 10' specimen as a gift from Briggs Nursery, Olympia, Washing- ton. It is being introduced by the Saratoga Hor- ticultural Foundation in California. The plant can Building stairs in the Memorial Hillside with Seattle Public Schools Work Program students, supervised by Scott Williams, Arboretum staff. Vol. 54: 3/Fall 1991 23 MADISON PARK HARDWARE — PM KSsasyi ‘ rM.vL*l:.|Vj r tr* ft 1837 42nd E. 322-5331 GARDEN SUPPLIES • PAINTS • TOYS • GIFTS Pruning with Design be seen in the Joseph A. Witt Winter Garden. 114- 91 x Chitalpa tashkentensis ‘Pink Dawn’ 115- 91 x C. tashkentensis ‘Morning Cloud’ (Bignoniaceae): selections of an intergeneric hy- brid between Catalpa bignonioides and Chilopsis linearis , received as cuttings from the Rancho Santa Ana Botanical Garden in California. Origi- nally hybridized in Tashkent in the then-USSR, this hybrid has coarsely willow-like deciduous foliage and is said to have an exceptionally long blooming period. 149-91 Araucaria angustifolia (Araucariaceae): a Brazilian monkey puzzle tree that we received as wild-collected seed. Ordinarily, this tree would be deemed too tender for Seattle, but this provenance collection may prove otherwise. 171-91 Desfontainea spinosa (Loganiaceae): a wild collection from Chile by the Arnold Arbore- tum, Jamaica Plain, Massachusetts, of a beautiful evergreen shrub with striking scarlet and yellow flowers. Timothy Hohn is the curator of living collections for the University of Washington Center for Urban Horti- culture and the Washington Park Arboretum, Seattle, Washington. Christina Pfeiffer is the Arboretum’s horticulturist. 24 Washington Park Arboretum Bulletin Book Reviews Designing! with Perennials. Pamela J. Harper. MacMillan Company, New York. 1991. 326 pages. ISBN 0-02-548180-0. $40.00. Pamela Harper’s new book does an excellent job of describing how perennials can be used in many ways in the landscape. She discusses growing them in borders between shrubs and sep- arately in island beds. A chapter is devoted to ground-cover perennials. Designing with Perennials is a book for the in- formed gardener and the landscape professional, alike. It has many beautiful photographs taken in gardens in England and in the United States, in- cluding Oregon and Washington State. The photographs illustrate the text very well and can be used by the professional designer to show pro- spective clients what can be achieved. Likewise, home gardeners can see groupings they would like to have in their own yard. Climate and soil differences in various parts of the country affect plant-growth habits, and although the book is pri- marily about gardening in the temperate areas of the southeastern United States, the Northwest reader will find most of the information in this book very relevant to their design needs. Most of the plants that Pamela Harper men- tions grow well in the Northwest. Some of her fa- vorites are my choices as well (e.g., Sedum ‘Autumn Joy’). I learned the identity of a tall blue aster I have been searching for; it is Aster ‘Climax’, a childhood memory. Unfortunately, I have not found it to be available in local nurseries. Some plants were new to me, among them being Amsonia and Curtonus which appear to be useful landscape plants. Amsonia tabernaemontana , a hardy Vinca relative of 2' tall, provides late spring color. In late summer, Curtonus blooms with orange-red trumpets similar to Crocosmia. Pamela Harper has a strong sense of design which she expresses in many ways. A chapter is devoted to how the shape and size of the planting area — whether border or island bed — affects plant selection. Plant placement also is discussed. One interesting concept is putting taller flowers in front of lower growing varieties so the flowers at the back are viewed through foliage. This is par- ticularly successful using tall grasses. The plant at the back should have brightly colored flowers such as Pyrethrum or maybe an annual ted Salvia. Another tall see-through plant might be Thalic- trum delavayi with heliotrope behind it. The lavender Thalictrum lightens up the dark purple heliotrope. Color of flowers and foliage are frequently men- tioned as design features. There is a lovely photo of the pale yellow Oenothera missouriensis grow- ing together with Coreopsis ‘Moonbeam’ as an example of using a monochromatic color scheme. The book covers many aspects of gardening, from selecting certain cultivars for their color of bloom to how to plant them for best effect. There are warnings about invasive plants, too. The most interesting chapter was on how perennials can be combined with shrubs in a mixed border for a variety of texture and color over a long season. Designing with Perennials is a book to be en- joyed a little at a time. I needed a note pad to jot down all the gems of information to be found in its pages. — Pat Roome Pat Roome, of Pat Roome Landscape Design, Inc., is a landscape designer and garden maintenance consult- ant in Bellevue, Washington. Her interests include perennial plants and ornamental shrubs. Pat teaches landscape and design classes at the University of Wash- ington Center for Urban Horticulture and at Lake Washington Vocational Technical Institute. She is editor of PlantSource Magazine which provides a monthly updated list of plants available in the wholesale nurseries of Washington and Oregon. Pat writes an ar- ticle on some aspect of horticulture for each issue of the magazine. Vol. 54: 3/Fall 1991 25 M ush i voms of Not tb A merica . Roger Phillips. Little Brown and Company, Boston. 1991. 319 pages. ISBN 0-316-70613-2. $24.95^ he new book by Roger Phillips addresses three to five times more species than usual- ly found in mushroom identification handbooks. The book is well organized and provides consider- able information for beginners. Numerous pictures show the nature and habitat of over one-thousand species of fungi and mush- rooms. Because of the many views of each species in the color plates, most of the salient characteris- tics are visible to the reader. Even though there are no books that contain all species of mushrooms for any area or region, many of our Pacific Northwest mushrooms are vividly displayed throughout the book’s pages. It is very helpful because of the large number of species represented, and makes for great armchair viewing activity. Many amateurs, professional amateurs, and professional mushroom enthusiasts already have this on their reference shelves. — Coleman Leuthy Coleman Leuthy is a member and past president of the Puget Sound Mycological Society and is on the edu- cation committee of the North American Mycological Association. Coleman is past president of the Pacific Northwest Key Council, which writes keys for identify- ing mushrooms without having to use the microscope. New on the Shelves of the Elisabeth C. Miller Library by Valerie Easton TTTith the profusion of new garden books, it V w can be difficult to find the perfect gift. As the holidays approach, any of these especially in- teresting newer titles would be welcomed gifts for the gardener on your list— or for yourself. Two recent publications should be at the top of the list of books for the Northwest gardener’s home library: Trees and Shrubs for Pacific North- west Gardens (John and Carol Grant. Portland, OR: Timber Press, 1990. ISBN 0-88192-145-9) and Trees of Seattle (Arthur Lee Jacobson. Seat- tle, WA: Sasquatch Books, 1990. ISBN 0-912365-34-X). Both are reviewed in the Arbo- retum Bulletin 52:2. Another title with a Northwest emphasis is Perennials: Toward Continuous Bloom (Anne Lovejoy, ed. Deer Park, WI: Capability’s Books, 1991. ISBN 0-913643-06-8). This is the first in a planned series featuring current American gar- den writers, and focuses on perennials. Due to its local editor, Northwest writers are well repre- sented. Article topics and writing quality vary widely, but it is a pleasure to read about the ideas, progress, and biases of more than 35 perennial ex- perts. Especially useful is learning about the favorite plants, including sources, of local gar- deners such as Peter Ray, owner of a Vashon Is- land specialty nursery; Jerry Sedenko, garden designer and writer; Judith Jones, fern expert; Susan Buckles, the gardener responsible for the ornamental borders at Children’s Orthopedic Hospital; and other local plant experts. A unique collection of interviews, Gardening from the Heart: Why Gardeners Garden (Carole Olwell. Berkeley, CA: Antelope Island Press, 1990. ISBN 0-917946-05-7) also emphasizes western gardeners. Looking for explanations as to why we garden, rather than the kind of informa- tion found in garden design books or plant ency- clopedias, Olwell interviewed gardeners from all over the United States who create and work in a wide variety of gardens. Personal gardening histo- ries, childhood memories, and feelings about gar- dening are expressed by Mary Kenady, who culti- vates 10 acres outside of Duvall, Washington; Loie Benedict, a plant lover who also gardens in 26 Washington Park Arboretum Bulletin Duvall; and Linda Bevilacqua, a “you pick’1 market gardener in Kent, as well as 1 5 other pas- sionate, involved gardeners. Excellent and un- usually detailed photographs, along with informa- tion on favorite plant combinations, organic gar- dening practices, and an overview of pesticide problems and alternatives, make this book as use- ful as it is pleasurable to read. Garden explorers will be pleased to see that there is a new series on North American gardens, with the second volume devoted to West Coast gardens. The Complete Guide to North Amer- ican Gardens , volume 2: The West Coast (Wil- liam C. Mulligan. Boston: Little, Brown and Company, 1991. ISBN 0-316-58909-8) covers gardens from Alaska to California, and includes Hawaii. It is of handbook size and format, with in- formation on hours, fees, directions, telephone numbers, amenities, and special features. What makes it special are its clear, beautiful color photos of each garden described. A fall color photo of the Washington Park Arboretum and a Japanese Garden spring photo with wisteria and azaleas in bloom are very enticing. Short essays on the gardens give a feel for what is special and noteworthy about each. There are some errors (the locks bordering the Carl S. English, Jr. Gar- dens in Ballard are actually 975-feet long, not 43 times that much), and some omissions (such as Lakewold, near Tacoma, Washington, and the Garden at Bishop’s Close at Elk Rock, outside of Portland, Oregon). However, the guide is wel- come for its regionalism and currency. It is also welcome for the photograph of Ohme Gardens on its cover, showing the blooms of sedum and thyme in the foreground and the panorama of the lush garden stretching out through the trees to the dry hills of Eastern Washington. A classic and extensively detailed survey of perennials has been significantly revised. The third edition of Graham Stuart Thomas’s Peren- nial Garden Plants or the Modern Florilegium (Portland: Timber Press, 1990. ISBN 0-88192- 167-X) is written by a man who believes that “a garden without herbaceous plants is almost non- existent.” To further the use of these plants, Thomas includes information on bulbs, grasses, biennials, ferns, woodland, and bog plants. He has grown “some nine-tenths” of the plants listed, and believes they should be used throughout the garden to complement other plants and struc- tures, not just in the traditional herbaceous bor- Cartier presents eyewear designed to enhance the expressive beauty of the eyes. Elegantly functional to frankly luxurious. Each created and signed by the world ’s most celebrated jeweler. This collection dramatically demonstrates what happens when the world’s most famous jewelers turn their attention to eyewear: quality materials, real craftsmanship, creative detailing, and a commitment to style and design integrity. All the classic Cartier touches are here: The steel and gold Santos look, the two-toned ribbed “rolling ring” motifs, the burgundy color accents, and the famous interlocking “C” signature. Each pair is made in precious palladium and finished in 22K yellow gold. From $540 to $1,210. THE 709 Broadway East, Seattle, WA 98102 Capitol Hill, (206) 328-4386 der. To help the reader do just that, most of the book consists of listings of over 2,000 species and a greater number of hybrids and cultivars, includ- ing information on height, color, flowering, and cultivation, along with personal notes, opinions, and a bit of history about each plant. This revision of Perennial Garden Plants in- cludes U.S. hardiness zones and over 250 further species and varieties. Clear color and black-and- white photographs help with identification, but most of the book is made up of the exhaustive list- ings. Also helpful is the section “Cuttings from My Notebook," which includes knowledgeable suggestions on color schemes, plants for wet areas, and evergreen perennials. If you plan on buying a book on perennials, also look at Pamela Harper’s new work, Designing with Perennials , reviewed in this issue. Now, as chrysanthemums are fading and the dahlias are spent, we wish we could prolong the pleasures of the garden for a few more months. Allen Lacy’s The Garden in Autumn (New York: Atlantic Monthly Press, 1990. ISBN 0-87113- 347-4) not only encourages the gardener to ex- tend the season, but claims that mid- August to Vol. 54:3/Fall 1991 27 GRAHAM STUART THOMAS Plants for Ground-Cover — renwtl Atitum — ^ — ASi PubiAbod in asstn iation w ith tin' RovaJ Hortk ultural Society — — — early November can be more than a time of rak- ing leaves and tidying up. Planting, transplanting, and weeding are ideally accomplished in the fall, and Mr. Lacy claims his garden is at its best and in full bloom in late September into October. Chapters on lingering perennials, perennials specific to the season, bulbs, grasses, annuals, and woody plants explore the variety of materials found useful throughout the autumn months. The expected Japanese maples, mums, and heathers are discussed, as are the more unusual and unexpected plants such as perennial salvias and lobelias, alliums, and Rosa glauca. Beautiful photographs inspire the gardener with the array of color, texture, pods, bark, fruit, and foliage pos- sible in the autumn garden. Valerie Easton has been a librarian at the University of Washington Center for Urban Horticulture since 1985. Also New Alber, John I., and Delores M. Alber. Baby-Safe Houseplants & Cut Flowers. Highland, IL: Genus ' Books, 1990. ISBN 0-9626066-1-8. Allison, James. Water in the Garden: A Complete Guide to the Design and Installation of Ponds, Foun- tains, Streams, and Waterfalls. Boston: Bulfinch Press, 1991. ISBN 0-8212-1839-5. Brooklyn Botanic Garden. Indoor Bonsai. Plants and Gardens, Brooklyn Botanic Garden Record (46:3, Handbook 125). New York: Brooklyn Botanic Garden, autumn 1990. ISBN 0-945352-58-1. Clarke, Ethne. Hidcote: The Making of a Garden. London: Michael Joseph, 1989. ISBN 0-7181-2938-5. Ferguson, John, and Burkhard Mucke. The Gar- dener ’s Year: A Practical Guide to Gardening in Rhythm with Nature. New York: Barron’s, 1991. ISBN 0-8120-6184-5. Gould, David R. Beyond Blackberries: A Foraging Guide to the Publicly Accessible Fruit and Nut Trees in Seattle. Seattle: SockMonkey Productions, 1991. Hobhouse, Penelope, and Patrick Taylor, eds. The Gardens of Europe. New York: Random House, 1990. ISBN 0-679-40041-9. Lacey, Stephen. The National Trust Guide: Lawns & Ground Cover. North Pomfret, VT: Trafalgar Square Publishing, 1991. ISBN 0-943955-42-4. Please, Peter, ed. Able to Garden: A Practical Guide for Disabled and Elderly Gardeners. North Pomfret, VT: Trafalgar Square Publishing, 1990. ISBN 0734 61-37-3. Sombke, Lawrence. The Environmental Gardener: The Solution to Pollution for Lawns & Gardens. New York: MasterMedia Limited, 1991. ISBN 0-942361- 28-8. Thomas, Graham Stuart. Plants for Ground-Cover. Portland: Sagapress, Inc./Timber Press, Inc., 1990. ISBN 0-88192-169-6. Walker, Richard B., and Stanley P. Gessel. Mineral Deficiencies of Coastal Northwest Conifers. Seattle: In- stitute of Forest Resources (contribution 70), Univer- sity of Washington, 1991. FLORA & FAUNA BOOKS Natural History Book & Print Specialists A Full Range of the Best Books in Botany & Horticulture Always in Stock Specializing in British Books • Timber Press • New and Used Books • RHS Kew Handbooks • Collections Purchased • Collins Field Guides • Search & Order Service • Ortho Books • Mail Service in the Pioneer Square area, 1 block from Elliott Bay Books 121 -1st Ave. S. - Seattle, WA 98104 - Mon-Sat 10-5 28 r Washington Park Arboretum Bulletin ^.Northwest r lower 0, and Garden Show Feb. 6-9, 1992 Washington State Convention Center • Seattle • Largest spring flower show in western North America • 25 full-size gardens • 300 commercial exhibits • 60 educational booths • 95 free seminars sponsored by Magazine • 60,000+ attendance 500,000 Official Show Programs distributed in advance Feb. 2 in Pacific, Sunday magazine supplement of Seattle Times/Seattle Post-Intelligencer newspapers. For further information contact show office 1515 NW 51st St., Seattle, WA 98107 Fax (206) 784-5545 Phone (206) 789-5333 A Scenes from the 25 gardens in 1991 show. ELISABETH C. MILLER LIBRARY ? FOR URBAN HORTICULTURE • vEKSSTY OF WASHINGTON, GF-15 SEATTLE* WASHINGTON 98195 ARBORETUM The Bulletin is published by the Arboretum Foundation Washington Park Arboretum University of Washington XD-10 Seattle, Washington 98195 NON PROFIT ORG. U.S. POSTAGE PAID SEATTLE, WASHINGTON Permit No. 126 miller library u OF WA GF-15 SEATTLE, WA 98195 An arboretum is a living museum of woody plants for education, conservation, research, and display.