HARVARD UNIVERSITY LIBRARY OF THE GRAY HERBARIUM '4 Digitized by the Internet Archive in 2017 with funding from BHL-SIL-FEDLINK https://archive.org/details/arnoldia54arno amoUia Volume 54 Number 1 1994 Ainoldia (ISBN 004-2633; USPS 866-100) is published quarterly by the Arnold Arboretuni of Harvard University. Second-class postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Single copies are $5 00. All remittances must be in U.S. dollars, by check drawn on a U.S. bank, or by international money order. Send orders, remittances, change-of- address notices, and all other subscription-related communications to; Circulation Manager, Ainoldia, The Arnold Arboretum, 125 Arborway, Jamaica Plain, MA 02130-3519. Telephone 617/524-1718 Postmaster: Send address changes to. Ainoldia, Circulation Manager The Arnold Arboretum 125 Arborway Jamaica Plain, MA 02130-3519 Karen Madsen, Editoi Editoiial Committee Phyllis Andersen Robert E. Cook Peter Del Tredici Gary Roller Richard Schulhof Stephen A. Spongberg Ainoldia is set in Trump Mediaeval typeface and printed by the Office of the University Publisher, Harvard University. Copyright © 1994. The President and Fellows of Harvard College Or AY Page 2 Restoring the Harvard Yard Landscape Michael Van Valkenbuigh and Peter Del Tredici 12 The Care and Feeding of the Noble Allee Marc Treib 24 "A Most Dangerous Tree"; The Lombardy Poplar in Landscape Gardening Christina D. Wood 3 1 Punctuating the Skyline: Alternatives to the Lombardy Poplar Karen Madsen 35 In Memoriam: Jennifer Reimer Quigley S. A. Spongberg 36 Arnold Arboretum Weather Station Data Cover: Lombardy poplars [Populus nigra Ttalica ) at Sceaux, France. Photograph by Marc Treib. Inside front cover: Newly planted trees in the Tercentenary Theater of Harvard Yard. Photograph by Karen Madsen. Inside back cover: Lombardy poplars in Chile. From the Archives of the Arnold Arboretum. Populus nigra 'Italica' 2 Harvard Yard Restoring the Harvard Yard Landscape Michael Van Valkenburgh and Peter Del Tredici The spirit of Harvard Yard resides in its canopy of trees, tall, reaching groves that define spaces and passageways and create an evocative sense of place. Simplicity and understatement are the prevail- ing qualities of Harvard Yard's landscape, the result of a New England aesthetic that might also be termed frugal elegance. It is an almost completely built artifice that has evolved over more than three centuries of intervention and transformation. As a composition, the land- scape and the buildings within Harvard Yard are inseparable. Yet it is the landscape — a simple order composed of a continuous ground plane of grass crossed with paths — that has re- tained the more enduring, timeless character. The lawn establishes a base on which a broad range of building types in various styles are sited. Overhead a high canopy of deciduous trees completes this majestic landscape. Com- bined, the lawn and the canopy unify the spaces of the Yard and engender a unique sense of place. The maturity of the tree canopy and the im- minent loss of most of the American elms have become pressing concerns. A nearly cata- strophic number of trees were felled during the last two decades. Many of these were elms that were infected with the Dutch elm disease, but many others succumbed to stresses common to the urban landscape: soil compaction, root damage effected during construction projects, salt used for ice melting, and fluctuations in the water table. Still other trees were lost due to damage in the snow and ice storms of the late 1970s and early 1980s. Despite the continual buzz of chainsaws in the Yard over the past two decades, few new trees have been planted. As a result. Harvard now needs to make up for lost time. Almost two hundred trees at semi-mature sizes must be planted throughout the larger Harvard Yard area to recreate the presence of the grove. Be- cause trees grow slowly, the need to replant the Yard's canopy has become urgent. In 1991 the University undertook a study of the series of large and small spaces that constitute Harvard Yard, broadly defined as the Old Yard, the Tercentenary Theater, Seaver Quad, the Science Center Overpass and Memorial Hall, Quincy and Prescott Streets. As a first step, an ad hoc tree committee was convened.* The product of this group's effort, a list of trees suitable for Harvard Yard, can be seen below. Sixty-eight trees have been planted this spring. Another six will be added this fall and two more next spring. The New Tree Canopy The predominating American elms (Ulmus americana) have imprinted themselves on all who are familiar with the Yard. As a species, the elm is fast growing, readily available, easy to transplant in large sizes; and highly tolerant of compacted soils. Its natural form provides a tall, high-branched canopy. Understandably, it was a favorite of our predecessors, but its fate strongly suggests that replanting not be domi- * Bernard Keohan, Robert Lyng, Robert Mortimer, Peter Del Tredici, Michael Van Valkenburgh, and Tim Barner. 4 Harvard Yard nated by a single species of trees, which might again leave the Yard vulnerable to the devas- tating effect of insects and diseases. All re- placements must be well suited to stressful urban growing conditions, and in the interests of a unified composition, trees with odd col- ored bark, flowers, or leaves should be ex- cluded since they would not blend with other species. To recreate a canopy reminiscent of the character of the American elms — to retain not only their memorable quality but also unim- peded views across the Yard — each of the main spaces should be planted with a careful blend of two, three, or four tree species. In combin- ing trees the visual character of each species in every season of the year must be considered: the overall form and color when the tree loses its leaves in the autumn,- leaf color in spring, summer, and fall; any significant flowers or fruit. The committee left open the possibility that occasionally an additional, single species may be added, or preserved, if it is an existing tree in good health. For example, the few re- maining white pines (Pinus strobus) should remain as effective counterpoints to the new canopy. Indeed, a new white pine will he planted this fall, along with a catalpa (Catalpa speciosa) and a horse chestnut (Aesculus hippocastanum), not so much for canopy re- placement but to help reinforce the existing specimens of the same species. In replicating the character of the American elm grove, which retained few branches below twenty feet above ground level, it must be re- membered that once a tree grows a branch, the height of that branch does not change with later growth. For this reason, high-branched specimens have been planted from the incep- tion of the Yard's new grove. Trees grown with lower branches removed to six or seven feet above ground constitutes the minimum stan- dard for transplanting into Fiarvard Yard. At the time of planting, additional low branches have been removed to a height of eight or nine feet above ground level. Branches should al- ways be removed when they are quite small, as the larger cuts resulting from the removal of more mature branches require more time to heal. Over the next twenty years, additional branches will be removed gradually as each tree increases in height. The recommended transplant size for new trees in Harvard Yard is five or six inches in diameter at six inches above the ground; this is typically a tree about twenty to twenty-eight feet tall. Re-training the form of the trees re- quires careful selection of specimens with good structural development and a strong central leader, rather than trees with several leaders. Many of the species on the tree committee's list, including the Japanese pagoda tree (Sophora japonica) and red oak (Quercus rubra), lend themselves, with attentive main- tenance, to a high-branched and elmlike form even though their natural character, when grown in an open location, is a low-branched and rounded form. A lightly shaded growing environment where there is competition for sunlight alters the growth habit of a tree and yields a reaching elmlike character. New trees, if carefully located in the light shade of other trees in the Yard, are encouraged to grow taller as they reach for the sunlight above. New trees have not been planted directly under existing trees, but rather outside their drip line. Within Harvard Yard there are numerous microclimates that affect tree growth. In se- lecting species, the nuances of each planting site have been carefully considered, with particular attention to soil type, drainage, wind, available sunlight and shade, soil mois- ture content created by variable drainage conditions, density of traffic, and extent of pavement coverage, which increases soil tem- peratures in the root zone in summer. Also considered was the proximity of new trees to existing large trees, which create root compe- tition and shade that affect their development. The tree committee recommended that all trees in poor condition be removed between 1993 and 1994. Trees rated in fair condition may have several years of life remaining and will not be removed — except for design rea- Harvard Yard 5 Newly planted canopy trees in the Old Yard (Karen Madsen). sons — until they decline further. In some in- stances trees in fair condition remain on our plan; these are especially venerable trees that, with special care and attention, may survive for many years. Old Yard To many, the Old Yard is Harvard Yard. It is the largest and oldest space, with generous pro- portions and a commanding presence. Its pe- rimeter of enclosing buildings, which define the sides of the space, is perceptively simple but spatially sophisticated. Through time the placement of buildings has foiled what other- wise would be an unrelenting length spanning the two long sides of the Yard (750 feet), yielding instead stepped and ambiguous alignments. In contrast, the short ends of the Old Yard (250 feet) are completed with single buildings. The stepped sides coupled with the stolid ends cre- ate an impressive volume that, when filled with trees, establishes an aura of calm power. The spirit of the Old Yard is largely attribut- able to its enveloping canopy of majestic de- ciduous trees, which create an embracing grove. While this grove has been dominated by the American elm for most of the twentieth century, other species have been included to produce a more complex composition. The form of these other trees, most notably red oak and honey locust, has been managed to make them more elmlike in character. Branches have been removed for the first eighteen to twenty feet of each tree. In the Old Yard, we have planted a mix of honey locust (Gleditsia triacanthos) , Japanese pagoda tree (Sophora japonica), red oak (Quer- cus rubra), scarlet oak (Quercus coccinea), and willow oak (Quercus phellos). The trees have been planted in four existing north-south rows with spacing irregular within the rows. A fifth row has been re-established in front of the west 6 Harvard Yard The tree canopy in the Tercentenary Theater is reinforced with new plantings installed by Hartney/Greymont, Inc., of Needham. MA (Karen Madsen). side of Thayer and Weld Halls. Red oaks were used in front of Thayer and scarlet oaks in front of Weld. Two rows of tulip poplar trees (Liriodendron tulipifera) form an allee to frame the statue of John Harvard. These rows start at the Johnston Gate and are embedded in the existing grove of the Old Yard. Hackberries (Celtis x 'Mag- nifica') have been planted west of the Johnston Gate, at the site opened up by the removal of the existing yews at the gate. These two trees, with their elmlike shape, take the place of two downed elms. Tercentenary Theater The Tercentenary Theater is the heart of Har- vard Yard and one of the major time-honored landscape spaces. The enclosure of the Tercen- tenary Theater was completed by Memorial Church in the 1930s. The symmetry of Widener Library and Memorial Church and the com- manding nature of their broad bands of stairs create a space that has became the symbolic center of the Yard. It is its geographic center as well and is the most important ceremonial space on campus, where people from the en- tire university gather for graduation and other celebratory events. The character of the grove of trees planted in the rectangular space further compliments the ceremonial quality of the Tercentenary The- ater. In contrast to the darker oaks and maples at the periphery of the space, honey locusts (Gleditsia triacanthos), with their fine tex- tured foliage, allow dappled light to permeate the center ground of the space and to form a halo of light in the middle. Additional honey locust trees have been planted to supplement the existing ones. Red maples (Acer rubrum) have been planted as a rectangular perimeter Harvard Yard 7 around the irregular placement of the honey locusts. This patterning will not be apparent until the autumn when the yellows of the honey locusts will be framed by the spectacu- lar scarlet foliage of the red maples. Yellow- woods (Cladrastis kentuckea), which bloom at commencement time, have been planted ir- regularly at the periphery of the space. Three Kentucky coffee trees (Gymnocladus dioicus) and two bur oaks (Quercus macrocarpa) were planted on the lawn west and north of Widener Library. The three legumes share a characteris- tic flat-topped crown, and although clearly dis- tinct from one another, have similar enough forms to create a sense of harmony. It is essen- tial that all trees planted in the Tercentenary Theater be limbed up from the bottom as they grow, to allow unobstructed views throughout the landscape. The new trees will appear young for ten to fifteen years, and then although they will still be quite small, they will begin to blend with the remaining large trees. Eventually two hundred-plus trees are to be planted; there are approximately three-hundred-thirty existing trees within the perimeter of the Yard Fence. The Tree List Following is the final list of tree species se- lected for planting in the Yard. The tree com- mittee gave careful consideration to overall visual character, leaf density, color, scale, and form. The list is intended to provide the land- scape architect with flexibility in dealing with the unpredictable issues of size and availabil- ity that inevitably complicate any landscape job. The list of canopy trees focuses on species with a strong tendency to form a tall, straight trunk and a broad, spreading crown in a rela- tively short time. Species marked with an as- terisk (*) are considered secondary choices insofar as they possess some characteristic that causes maintenance problems; are slow- growing; are difficult to transplant; or hard to locate in nurseries. The decision to use these secondary species should be based on finding the right location for them as well as the size and quality of specimens available from nurs- eries. Tree species suitable for the periphery of the Yard are presented in Part II. PART I: CANOPY TREES Acer rubrum (Red Maple) This midsized tree produces great spring and fall color and is tolerant of compacted soil con- ditions. Red maple will perform well in the Yard and will add interest in the fall, a feature that is currently lacking. Acer saccharum* [Sugar Maple) This tree has beautiful fall color but is intoler- ant of compacted soil and road salt. It has a roundheaded crown and casts a dense shade. In the Yard it will need to be carefully sited away from areas with heavy pedestrian or vehicular traffic. Celtis laevigata* (Sugarberry) This species, which is very tolerant of com- pacted soils, is well worth trying in the Yard although specimens may be difficult to find. It is larger and more robust than the common hackberry, Celtis occidentalis, and can be quite elm-like in its form. Gleditsia triacanthos var. inermis (Thornless Honey Locust) Because of its graceful form, the honey locust is the tree that many horticulturists view as the ideal replacement tree for the American elm. We should be cautious not to overuse the tree as was done with the American elm, given that it is susceptible to a number of serious dis- eases. The fact that grass grows well under the light canopy of the honey locust makes it an excellent choice. Using male selections will reduce the litter problem posed by seed pods. Gymnocladus dioicus* (Kentucky Coffee Tree) Kentucky coffee tree, while it has a very sparse growth habit and stark winter outline, is a strikingly beautiful tree. Like the honey locust it casts a light, delicate shade that allows grass to prosper. Male selections should be planted if possible. 8 Harvard Yard Liriodendron tulipifera (Tulip Poplar Tree) Tulip poplar tree has an upright growth hahit and very beautiful flowers and leaves. It grows extremely large, so should he planted only in larger spaces. It forms a tall, straight trunk and has good yellow fall color. Magnolia acuminata* (Cucumber Tree) Cucumber magnolia is a very stately single- trunked tree that could be used sparingly in the Yard. It does not appear to have any disease problems, but its large leaves might be seen as a litter problem in the fall. Quercus bicolor (Swamp White Oak) Swamp white oak would be a great addition to the Yard if large specimens can be located. It is slow to establish itself, but well worth the wait. The white oak, Quercus alba, is equally acceptable from a landscape point of view but considered more difficult to transplant. Quercus coccinea (Scarlet Oak) Scarlet oak is similar to pin oak in habit and leaf shape but is somewhat slower growing and more difficult to transplant. It does, however, have much better fall color than pin oak. Quer- cus shumardi, the Shumard red oak, is similar in many respects to the scarlet oak, and some growers consider it a better performer. Quercus palustris (Pin Oak) Pin oak casts a lighter shade than red oak and needs to he limbed up in order to see its beau- tiful, smooth trunk. It is tolerant of both poorly drained and compacted soils. When young, this species tends to hold its brown leaves throughout the winter. This problem can be overcome by selecting trees in the nurs- ery that have outgrown this "juvenile" trait. Quercus phellos* (Willow Oak) The narrow, willowy leaves of this beautiful tree cast a light shade. It is relatively easy to transplant and tolerant of wet, compacted soil. A common street tree in the south, the species has traditionally been considered marginally hardy in the Boston area. However, experience indicates that trees from the northern parts of its range (central New Jersey) are hardier than plants from more southern areas. If northern The shadow of an American elm falls on Stoughton Hall in the Old Yard (Peter Del Tredici). trees can be located in a nursery, willow oak would make a nice addition to the Yard. Quercus rubra (Red Oak) Red oaks are already abundant in the yard, but a few more could well be planted. Because it casts a dense shade, trees of this species should not be planted too closely together or the grass will suffer. Many other tall oaks, including Q. acutissima, imbricaria, and macrocarpa, would perform well in the Yard, and their use is limited only by their availability. Sophora japonica* (Japanese Pagoda Tree) The Japanese pagoda tree is a beautiful alterna- tive to the honey locust. It does, however, have a tendency to retain its lower branches. For this reason, tall specimens that had been limbed up in the nursery should be specified for planting in the Yard. Harvard Yard 9 PART II: PERIPHERY TREES These are species suitable for special purposes. In general, they are somewhat smaller in stat- ure than the canopy trees listed above; have a narrow as opposed to a spreading growth habit; or show a pronounced tendency to retain their lower limbs. They should be used near build- ings or around the edges of the Yard to lower the canopy. Betula nigra (River Birch) For planting in the Yard, river birch that has been trained to a single trunk should be used, as opposed to specimens grown as a clump. The tree has peeling, buff-colored bark and is very tolerant of compacted soil. It is the only species of birch that can be considered reliably disease-resistant. Cercidiphyllum japonicum (Katsura Tree) This is a beautiful, midsized tree that casts a light, delicate shade. It would make a nice ad- dition to the Yard and is relatively mainte- nance free. Cladrastis kentuckea (lutea) (Yellowwood) This elegant leguminous tree has performed well in other locations at Harvard and would grow well in the Yard. The tree produces its beautiful white flowers in early June, just in time for commencement. Because yellowwood tends to keep its lower branches, it needs to be sited in locations where heavy pruning is not required. Fagus sylvatica (European Beech) This long-lived tree is already widely planted throughout Harvard. It is an excellent choice for the north sides of buildings that are shady and cool and where foot traffic is minimal. We particularly recommend the upright form 'Fastigiata' for areas where there is not enough room for a full-sized, spreading specimen. Ginkgo biloba (Ginkgo) While stiff and awkward when young, the tree develops great character as it ages. It is tolerant of a wide range of soil conditions, and if given enough sun and moisture, grows quickly. The fan-shaped leaves turn a beautiful clear yellow in autumn. Only male plants with a spreading habit, as opposed to the narrow 'Fastigiata' clones, should be planted. Larix decidua (European Larch) This deciduous conifer is tolerant of com- pacted soil and would add a nice touch of yel- low fall color to the yard. Being of relatively narrow growth habit when young, it could be used in fairly close proximity to buildings. It can be limbed up with impunity. Liquidambar styraciflua (Sweet Gum) Sweet gum is very tolerant of compacted soils and has extremely beautiful fall color. The tree is not a favorite with maintenance people be- cause it drops spiny "gumballs" in the winter, two months after leaf fall, necessitating a sec- ond cleanup. Nyssa sylvatica (Tupelo or Black Gum) This species has sensational fall color and beautiful winter form. While somewhat slow to establish itself and difficult to transplant, tupelo would make a nice addition to the Yard if we could locate large specimens. Tilia petiolaris (Pendant Silver Linden) This is one of the most beautiful of the lindens because of the silvery white underside of the leaves and because the branches are gracefully weeping. The tree grows to be quite large and, relative to other lindens, has good fall color. Ubnus parviflora (Lace Bark Elm) This is one of the few elms that is truly resis- tant to Dutch elm disease. While not as tall or graceful as the American elm, it has beautiful, exfoliating bark and an airy crown composed of small leaves with good fall color. On the down side, lace bark elm tends to leaf out sev- eral weeks later than other elms. Zelkova serrata (Zelkova) This species is often touted as a replacement for the American elm, but it is considerably smaller in stature. For planting in the Yard, we recommend using one of the tall, upright selec- tions such as 'Village Green', as opposed to random seedlings. 1 0 Haivaid Yard The previous list identifies the trees that the committee selected as appropriate for use in Harvard Yard; the list on the right gives the trees actually obtained in nurseries for the first phase in the Yard replanting program. The map shows which existing trees will be retained, which will be removed or transplanted, and where new trees will be sited. The Old Yard (on the left of the map) is bounded by Holworthy, University, and Grays Halls. The Tercentenary Theater is delineated by Widener Library, Memorial Church, and Sever and Univer- sity Halls. Sever Quad (on the right) extends from Sever Hall to Robinson and Emerson Halls and Quincy Street. HARVARD YARD REPLANTING PROGRAM PHASE ONE (1994) lELUpS BROCMCf HOLWORTHY CANADAY HOLDEN CHAPEL MEMORIAL CHURCH ROBINSON harv.ard MASSACHL'SETTS jCRAYSI BOYLSTON LAMONT O EXISTING TREE TO REMAIN (g) EXISTING TREE TO BE REMOVED <§) EXISTING TREE TO BE TRANSPLANTED O NEW TREE "''OGI.ESIH WassacHi 'vrf CANADAY o O o o 'I CANADAY .^19 Harvard Yard 1 1 Qty. Botanical Name Common Name Old Yard Tercentenary Theater Sever Quad 9 Acer rubrum 'Red Sunset' Red Sunset Red Maple 9 2 Acer saccharum 'Green Mountain' Green Mountain Sugar Maple 2 1 Aesculus hippocastanum Horse Chestnut 1 2 Catalpa speciosa Catalpa 2 3 Celtis X 'Magnifica' Magnifica Hackberry 3 7 Cladrastis kentuckea Yellowwood 7 6 Gleditsia 'Shademaster' Shademaster Honey Locust 4 2 3 Gymnocladus dioicus Kentucky Coffee Tree 3 2 Liquidambai styraciflua Sweet Gum 2 12 Liriodendion tulipifera Tulip Poplar Tree 9 3 2 Nyssa sylvatica Tupelo 2 1 Pinus strobus White Pine 1 1 Quercus acutissima Sawtooth Oak 1 1 Quercus alba White Oak 1 1 Quercus imbricaria Shingle Oak 1 4 Quercus coccinea Scarlet Oak 4 3 Quercus macrocarpa Bur Oak 2 1 2 Quercus palustris Pin Oak 1 1 4 Quercus phellos Willow Oak 3 1 5 Quercus rubra Red Oak 5 5 Sophora iaponica Japanese Pagoda Tree 5 Michael Van Valkenburgh is chair of the Department of Landscape Architecture at Harvard University's Graduate School of Design and principal of Michael Van Valkenburgh Associates, Inc., Landscape Architects. Peter Del Tredici is Assistant Director for Living Collections at the Arnold Arboretum, and also teaches at the GSD. The Care and Feeding of the Noble Alice Marc Treib Two of France's most engaging seventeenth-century landscapes are once more being rethought. The story goes that a certain professor of land- scape architecture at a California university was dismayed hy what a French student had proposed for her second planting design project. The trees were, in fact, arranged in two very straight and parallel lines, arranged in what in her country of origin is termed an allee. The professor's sole comment was, "Hmmm. So you've lined them up again?" After a moment or two of searching for a more pointed response, he played his trump card, "But what if one should die?” What indeed? He needn't have worried. Af- ter all, trees have been growing — and dying — in French allees for three centuries, more or less. But questions of life process within the garden are central to any landscape design, and to some extent they are made more transpar- ent in gardens conceived geometrically. When the pattern is apparent, the presence — or ab- sence— of any single element is highlighted. If a tree anchoring the corner of a square is miss- ing, that loss is more noticeable than one fallen within an informal clump. But in spite of the test of horticultural skill, formal gardens have been created in virtually every part of the world, either as domestic or imported prod- ucts. Trees arranged in lines have constituted a central feature of landscapes from the tunnello of Renaissance Italian gardens to the allee of French formal gardens to the street trees of nineteenth-century American cities. Allees are a magical part of the formal garden. But what if one should die? Versailles may be Andre Le Notre's largest work, but two of his most engaging designs are the gardens at the Tuileries and the park at Sceaux. The first has always been an element of the city, now circumscribed by Paris and the Seine. Like Central Park it is a respite from urbanity rather than a place where the city meets the field. Sceaux, on the other hand, lo- cated south of the capital, was created as an exurban estate to serve as a retreat from both the city and the suffocating protocol of the court. Today, it hosts dog walkers, runners, the elderly, soccer fanatics, model boat pilots, lovers, and those who derive pleasure from photographing long lines of Lombardy poplars. The Tuileries Until 1871, the gardens of the Tuileries spread outward from a palace of the same name, which had been recast during two prior rebuildings. By 1576, the chateau had already broken out of the enclosure surrounding the almost perfectly rectangular garden of the me- dieval structure.' The domain changed drasti- cally with Louis Le Vau's major building renovation of 1664 and the vast plan for the grounds proposed by Andre Le Notre (1613- 1700), the royal gardener.^ Tuileiies. Newer plantings in the grid of the Grand Convert. Horse chestnuts predominate (Marc Treib). 14 Noble Allee Tuileries. The central allee extending the axis of the Louvre to the arch of La Defense. Many of the trees are relatively young (Marc Treib). His scheme, which was more or less realized hy 1680, figured the garden as a play of varied arabesques planted within rectangular par- terres,- the dimensions of each were carefully adjusted to conjure a sense of regularity when the site wished otherwise.^ Typical of Le Notre's designs, many of the purely geometric figures were adjusted to counter the foreshort- ening apprehended from the palace to the east, from which point the principal views were cast. To disguise the slope across the site, hanks were raised along its northern and southern edges. Ramps joined the principal levels and a set of horseshoe-shaped ramps connected the ground with the embankment at the garden's western terminus. In Le Notre's time rows of trees extended the thrust of the axis from palace to fields. Today a forest of regularly planted (mostly) horse chestnuts (Aesculus hippocastanum) extends the line through from the Tuileries, past the vast Place de la Concorde, along the Champs-Elysees to the Arc de Triomphe, through the Porte Maillot and, as of 1989, on to the square arch at La Defense. Le Notre's vision was elegant, restrained, and gridded; architectonic areas adjacent to the palace gave way to bosks of mixed plantings. Here, horse chestnuts planted on a grid roughly fifteen feet apart (known today as the "Grand Convert") defined spaces within the larger space, provided shade as a respite from the summer sun and served as a screen for dalliance. As depicted in contemporary en- gravings, the design of the bosks was not consistent. Some were high, some low; some intricate, some simple. This permitted, within a structural theme, variation in form, use. Noble Allee 1 5 and amount of sunlight within an order im- mediately perceived. On the north terrace, silkworm-nourishing mulberry trees had been planted during the royal experiment to develop a silk industry. Horse chestnuts replaced them in 1677 as part of the great renovation, at which time spruce also entered the garden.^ In other parts of the garden, lindens replaced elms, originally planted in clipped bushes of varying heights and trees of varying species. The Tuileries had traditionally been open to the polite segments of the population,- in the aftermath of the Revolution the park became a National Public Garden.® But political imbro- glio nevertheless took its toll on the vegeta- tion and the chateau. Burned by the Paris Commune on May 23, 1871, the Tuileries pal- ace stood as a ruin for over a decade while its fate was debated. In 1882, the remnants of the building were pulled down, the site was cleared and reformed as a link between the Louvre and the Tuileries. In the later part of the nineteenth-century, during the reign of Napoleon III, the land that once accommo- dated the palace was reserved for imperial use.^ Over the centuries various species of trees — London planes (Platanus x acerifolia), for ex- ample— crept into the garden although horse chestnuts continued to predominate. In 1990, an invited competition was held for the redesign of the Tuileries gardens.** While the principal instigation for the contest was the great renovation by 1. M. Pei to the adja- cent Louvre, the garden itself was in serious need of study and reinvigoration. The care of the garden had been attached to the duties of the architect for the Louvre; no master plan guided maintenance and replanting, and over time the grounds began to show the piecemeal decisions of generations of gardeners. The scheme selected for execution (by Pascal Cribier and Louis Benech with Francois Roubaud) accepted the Le Notre structure as a framework within which to work, but called for major reformations to the design of the bosks and to the ground beneath the trees. New pools were to be added, new bedding, new A model of schemes for the Tuileries by Cribier- Benech-Roubaud (foreground) and Wirtz (radiating lines in the background. The Seine is on the right (EPGL/ F. Caplaine). plantings, new modulations of the ground plane,- all within Le Notre's prevalent structure.^ The results appear, at first glance, to be con- servative and archaeologically pure, with a prevalent formality that conforms to the his- torical structure of the park. But with a more careful viewing, one finds changes effected at the level of horticultural execution. Within the bosk areas, for example, new plantings of linear hedges will softly articulate the space beneath the trees. Most of these lines will remain low, planted with Alexandrian laurel (Danae racemosa), flowering raspberry (Rubus odoratus), and cranesbill geranium (Geranium maciorhyzum). In certain areas, however, the vegetation will form a true hedge. The proposed lines of hedges will be 16 Noble Allee Tuileries. A principal allee paralleling the Rue de Rivoli, seen with the raised embankment at the far right (Marc Treib). purposely overwatered and used as irrigation for the horse chestnuts, which have not prospered in the polluted Parisian air, a prob- lem compounded hy relatively dry summers of late. The landscape architects have also produced a protocol for maintenance and restoration to guide future work within the gardens. Having been a royal domain, the Tuileries remains di- rectly under the administration of the Minis- try of Culture's Department of Preservation, and prior to the competition there had been no firm policy for maintaining the integrity of the Le Notre or any other design. Instead, as is so often the case, the decisions were made by the gardeners on a day-to-day, item-by-item basis. Historically, the royal gardeners seemed more interested in sustaining a planted rhythm than in maintaining a species-pure planting. Although the gardens have relied on horse chestnuts, a number of alien species have been planted: one London plane, for example, is dated as about one-hundred-fifty years old. Other species were planted as the horse chest- nuts were lost.'° Policy toward planting continues to evolve. Mr. Jean Schnebelen, technical director for the Department of the Hauts-de-Seine's Espaces Verts (forests, parks, and gardens), noted that the horse chestnut, long the mainstay of French parks and formal gardens, is becoming increasingly more difficult to procure; nurser- ies prefer to cultivate lindens, and hence, these are more available. Horse chestnuts are also plagued by a fungus that appears at the end of the growing season and whose effect is only too noticeable in the brown edging of the leaves in late summer and autumn. In place of the golden tones taken by their northern cous- ins, in Scandinavia for example, the canopies Noble Alice 1 7 Tuileries. A typical bosk in the Grand Convert (Marc Treibj. of the trees in the Paris area appear as an unat- tractive agglomeration of dun-toned pennants hanging limply from their branches. Today, the multiple allees are far from pure in family and age, although the effect of the gridded bosks overwhelms these disparities. Only the specialist would notice that all is not coherent in the state of the Tuileries; the Le Notre structure predominates. Sceaux If the Tuileries is an urbane and restrained green setting in which the city echoes, the park at Sceaux is a gash of geometric order in- cised into the countryside. The chateau one sees today is not the original built around 1670 by the same Jean-Baptiste Colbert who man- aged the seventeenth-century renovation of the Tuileries gardens. That structure, like the palace of the Tuileries, was destroyed in the last century. The existing building, an emblem of the decline in taste and means in the centu- ries that followed in the wake of the Grand Siecle, is undersized and meager in comparison to the park itself. At the request of Colbert's son the Marquis de Seignelay, Le Notre executed major renova- tions and additions to the gardens from 1685 to 1696.'* The cross axis, set parallel to the chateau terrace, was strengthened by a new and quite Grand Canal, which collected groundwater while contributing to the garden an enormous mirror in which to reflect the skies and the glory of the patron. In the earli- est existing plan, which dates from 1730, the triple allees of trees surrounding the Grand Canal are carefully delineated, but the species of tree intended by the landscape architect can- not be ascertained with any precision. They are rendered only as generic shapes; no specif- 1 8 Noble Allee Sceaux. Detail of the 1 730 plan (Musee de I’lle de France). ics are listed. Perhaps the available or accept- able species were so well established that there was no need to note them. Perhaps the land- scape architect was more interested in the structural and spatial purposes served by the long rows of trees and less interested in the means by which to realize them. Elm, horse chestnut, and slightly later, linden, were frequently used in formal gardens such as these, and one can assume that at least one of these species would have been used at Sceaux (that is, if the allees were ever planted in their entirety). Whatever the species, the trees had long de- teriorated by the first decades of this century. By the 1920s the entire park was in desperate condition. Segments of the stone walls of the Grand Canal had collapsed, and only scrubby planting maintained the lines intended by Le Notre. The site was considered a health haz- ard, the canal waters were stagnant and fetid, and the once majestic water feature was caus- tically described as "an open sewer." Ownership of the park was transferred from private ownership to the Department of the Seine in 1923, and the public cry for greater attention ultimately resulted in a major refur- bishing of the park.'^ The canal, which had been the target of public abuse, was drained, rebuilt, and waterproofed;*^ an allee of Lom- bardy poplars was planted to ring the canal. The refurbished park was officially opened in 1935. The landscape designer Russell Page, vis- iting Sceaux in the mid-1930s, could report: "Now the canal has been cleaned; lines of Lombardy poplars have been planted down each side and there are boats and facilities for swimming. The work continues and, by de- grees, as much of the old Park as possible will be developed in playing fields and tennis courts. By the end of the 1930s the trees were beginning to mature and by the close of the following decade, they began to display signs of the majestic scale they possess today. Populus nigra 'Italica' entered France for the first time only in the mid-eighteenth century, that is, long after Le Notre. Thus there was no historical precedent for this choice of tree. But today the poplars are so dense, dramatic, and architectonic, that it is difficult to conceive of the canal without them. The Lombardy poplar is a tree accepted by gardeners but adored by architects. Cylindrical in shape with relatively quick growth and heights up to one-hundred feet, the Lombardy poplar is the perfect ingre- dient with which to create green architec- ture.'^ It also appeals to those who would realize a regrowth quickly. On the down side, the structure of its wood is brittle, the tree is relatively short-lived, and its roots can be invasive. They tend to destroy foundations like canal walls although this has not been a problem at Sceaux after the work in the 1930s. Within the last few years, the poplars have matured to a point where their continued existence has become questionable. At sixty- five-plus years, they have nearly reached the NEWS fr o m the Arnold Arboretum A New Relevancy Robert E. Cook, Director The Historical Challenge More than a century ago, a new institution was born through the vision of three men. Frederick Law Olmsted, newly appointed architect of Boston’s park system, designed an extraordinary plan for the land. Charles Sprague Sargent, newly appointed head of the Arnold Arboretum, directed the assemblage of a magnificent collection of trees for scientific research. Charles William Eliot, newly appointed president of the Harvard Corporation, declared this Arboretum to be an essential part of a great educational enter- prise, Harvard University. Fifty-four years after its found- ing, the Arboretum faced a grave challenge upon the death of Sargent, its first and only director. How would this vision, nurtured by his leadership and supported by the annual generosity of his close associates, survive the finan- cial storms ahead without the living spirit of its leader? Only a strong investment in the future. through the creation of an endow- ment fund in his memory, would secure the measure of financial sta- bility needed to sustain its mission to collect and study the trees of the world. A goal of $1,000,000 was set, and a campaign was launched. A loyal group of Sargent’s friends from across the country rose to meet this challenge. And what friends they were. In New York alone, the Charles Sprague Sargent Memorial Fund was chaired by Henry James with J. P. Morgan serving as treasurer. They Arboretum education ‘initiatives aim to make children partners in science learning. raised $1,021,884. Today, the Arnold Arboretum is known the world over for its leadership in the study of trees, especially those of the Asian continent. A New Relevancy It has been sixty-six years since that great campaign on behalf of the Arboretum. Today the institu- tion faces a new challenge. Our world has grown very small in the last half century. The common environment that sustains our daily existence is under increasing assault. Where once Sargent would have traveled thousands of miles to collect the seeds of exotic Chinese trees, today those rich for- ests of temperate Asia have been decimated by the axe. Over the past several decades, the accelerat- ing loss of forests in tropical Asia has contributed to irreversible changes in the very climate that surrounds us all. Closer to home, the next generation of children, who will inherit this altered world, are leaving our school system unpre- pared for the future. We are fail- ing to educate all Americans in the basic understanding of science and technology that permits them to evaluate critical environmental issues and execute the obligations of responsible citizenship. It is no surprise that all of our institutions are being called upon to transcend their traditional mis- sion of scholarship. Much more than in the past, their resources are being asked to address urgent social, economic, and international issues through direct service to society. The Arboretum has heard this call, and we are in a unique posi- tion to respond. On the one hand, as part of Harvard University, we curate the collections and cul- tivate the knowledge that will be required for the resolution of pressing problems. (See box below on the upcoming expedition to China.) On the other hand, as part of the urban fabric of Boston, we experience an added obligation to transform this knowledge into ser- vice for the community around us. Consequently, we have begun to answer this call. With the support of interna- tional agencies such as the World Bank, we are bringing the exper- tise of our staff to collaborate directly with the governments of Asian nations. Working closely with country scientists, we are providing assistance for the con- servation of their critical biologi- cal resources through botanical exploration and inventory, the identification of promising medic- inal plants, and the generation of forest management policies that can enhance sustainable development. Here in our own community, the Arboretum has become a cen- ter for science learning among the schoolchildren of Boston. Each year we bring hundreds of class- rooms to experience our land- scapes, and we work directly with elementary teachers to enhance their knowledge of basic biology and support their instruction of science in the classroom. Through the use of telecommunications technology, we will soon link neighboring schools in Boston and Brookline directly with each other and with the educational resources of the Arboretum. This electronic community will reinforce the development of a social commu- nity for science learning through our collaborative work with fami- lies, teachers, and their students. Because this service to society is an amplification of our historic mission, it places new demands on our financial resources. We must continue our traditional role of curating our collections and fos- tering scholarship. At the same time we must confront a challenge today that parallels that con- fronted by Sargent’s associates sixty-six years ago. How can we ensure that our present commit- The Arboretum is pleased to announce its participation in a plant-collecting expedition to Wudang Shan Mountains in Hubei Province, China, planned for Fall 1994. As a member of the North American China Plant Exploration Consor- tium (NACPEC), which will cooperate with the Nanjing Botanical Garden in this venture, the Arboretum will be represented by Peter Del Tredici, Assistant Director for Living Collections. Other members of the Consortium who will be participating in the trip include Longwood Gardens, Morris Arboretum of the University of Pennsylvania, and the U.S. National Arboretum. 2 ment to apply our knowledge to urgent societal problems will not erode in the face of future finan- cial pressures? The Challenge for a New Generation We must look once again to our friends for help. Our goal is $8,000,000, to be secured in an endowment for the service of a new relevancy in our mission. This goal matches, in today’s dollars, the aspirations of the Sargent Memorial Fund sixty-six years ago. As part of The University Campaign, it reaffirms the vision of our founders and the commit- ment of Harvard to it. The Arbo- retum Campaign calls forth the confidence and support of our friends to invest in the future of our augmented mission. At a time when our children and our world look to us for leadership, the chal- lenge is clear and our obligation unambiguous. With this help, we shall meet this challenge again. Adapted from the May 13 Supplement to the Harvard U niversity Gazette. Kim E. Tripp The very first impression was of snow — deep in spots, and cold down my boots — but definitely not too deep to keep me from tramping (and sliding, slipping, and bumping) along a slick coni- fer path to the firs — firs with whom I had been greatly looking forward to renewing a friendship. That was on the first day, and I finally stood below one of the Abies X umbellata, whose limbs were bowed ever so slightly with that same snow. Snow that, while less than thrilling down my boots, was perfect garb for the striking dimplecone fir. Snow that seemed to somehow stay miraculously new and fresh for weeks (because, in reality, it actually did — I’m cer- tain it snowed at least once a day during my first weeks here). Snow that, after seven years in snowless climes, was nothing less than sheer pleasure to me, even as it hung on in stubborn, dirty lumps, melting into April’s mud. The snow was an old friend made new again for me by the trees at the Arnold — a kind of arboreal renew- al I keep finding around every bend in the living collections. The Arnold Arboretum has a long history of plants and plantspeople, a history that is Kim Tripp arrived at the Arboretum in February as a Putnam Fellow with a two-year appointment to do research, teaching, and writing focused on the Arnold’s living collections. Kim comes to us from the North Carolina State University Arboretum where she worked with Dr. J. C. Raulston as a postdoctoral research associate. She acquired her Ph.D. in Horticultural Science from North Carolina State and an M.S. in Vegetable Crops from Cornell University. She is a researcher with many skills and an impressive list of publications. At the Arnold she will be engaged in the evaluation and propagation of selected collections (including A/w«5 and Cephalotaxus), and in basic plant physiology research. She’s seen above with Cephalotaxus sinensis. First Impressions of the Arnold Arboretum from a Winter Transplant 3 Karen Madsen never far from any endeavor here. The historical legacy of over 120 years of dedicated work by many individuals naturally runs the hu- man gamut from bungling to bril- liance, but it is apparent to any newcomer that brilliance has more often than not won out. As a re- sult, the living collections at the Arnold are one of the great gifts of that historical legacy to the world. But the Arnold’s living collec- tions are much more than a living legacy. As I go off in search of each day’s elusive treasure (I know that last Cephalotaxus must be down this path somewhere . . .), I am struck by the sense of newness and ongoing evolution in these 265 rolling acres of woody plants. It is a sense that comes with the new growth on venerable Pkea wilsnnii. with freshly dug nursery trees stacked ready for planting, with the flats of rare young seed- lings growing on in the green- house, with each unexpected encounter of the plant kind (Oh! Here’s Styrax ohassia!), or with the late evening light glowing through the grove of American beeches. After only a few weeks of exploring the grounds, I have already found favorite plants and places but, all of my efforts to the contrary, I have only begun to scratch the surface of the mind- boggling wealth of plants here. It is that mind-boggling wealth of plants that brings some- one like myself to the Arnold. My efforts to understand the growth and “behavior” of plants in horti- cultural environments, especially as relates to their roots, has often left me scratching my head over the unexpected differences be- tween very closely related plants grown in the same environment. The environments we create for landscape plants generally bear little relationship to the environ- ments in which those plants origi- nally evolved and, therefore, can be far more stressful because of those disparities. Simple differ- ences, like a plant’s genetic dispo- sition to invest more growth in roots than shoot, can allow it to thrive in environments fatal to other plants. The living collec- tions of the Arnold offer an unpar- alleled opportunity to explore such differences in growth across an astounding breadth of plants, both between and within botani- cal families and genera, from an impressive range of native envi- ronments. I will be exploring such differences in growth in search of patterns that relate to their perfor- mance in different environments. By increasing our understanding of how woody plants survive and prosper in managed environments, we improve our chances of carry- ing a strong diversity of trees into the increasingly stressful and ur- banized environs of the future. I have been delighted to dis- cover that the chance to work here offers me excellent access not only to the living collections them- selves, but also to the experienced and insightful staff of the living collections — a unique opportunity that has already led to rewarding exchanges of ideas and informa- tion. In addition, the libraries are a world-class resource, where one can easily and happily lose entire days without realizing they have gone by and where I have found time to begin research for some of my writing projects. But my first impressions of the Arnold Arboretum invariably come back to the plants, the trees, the thousands of wonderful woodies spread across Olmsted’s lovely landscape through which one can wander again and again, from winter through fall, and con- tinue to learn for a lifetime. Old giants and young saplings, fond familiars and exciting unknowns, native groves and exotic speci- mens, are all growing together ro continually re-create this arbore- tum. This is a place of great com- plexity, a place of rich tradition and significant history, of modern challenge and new opportunity, of disciplined research and pure silvan magic — an unforgettable place I am coming to know as the Arnold. Spring Planting Peter Del T redid Julie Coop and Susan Kelley. After the unforgettable winter of 1993—94, the staff and grounds crew of the Arnold Arboretum were particularly anxious to start the year’s spring planting. As of this writing, seventy-five new trees have been planted on the grounds with an equal number yet to go in. "We are most excited about the dozen new birches that have been set out, especially in view of the tremendous losses we have experi- enced in that genus over the last two years (seventy-plus trees re- moved). In terms of impact on the collections, devastation of the birches by the bronze birch borer 4 Karen Madsen Karen Madsen has been equal to or greater than that of the elms by Dutch elm dis- ease. We wish the new birches a long and fruitful life. Other notable additions to the collections are a small group of tupelos ( Nyssa sylvatica) along the southern edge of Dawson Pond, including a rare specimen of Nyssa sylvatica ‘Pendula’. We’ve also planted two new hardy pecans (Catya illinoensis) as companions to our one lone specimen. Come around in ten or fifteen years, and we’ll have our own sweet pecans to brag about. John Olmsted and John DelRosso pruning a honey locust on Peters Hill. Jim Nickerson with the debris from the clean-up of the Lilac Collection. Steve Spongberg, Peter Del Tredici, and a newly planted Aesculus x carnea ‘Briotii’. From left in front: John Olmsted, Jim Papagiris, Mark Walkama, Julie Coop, Joan Mullins; in the rear, John DelRosso, Karl Holmes, Pat Willoughby, Bruce Munch, Dennis Harris, Luis Colon, Bob Famiglietti (standing), and Don Garrick. Kenny Clarke, Jim Nickerson, and Maurice Sheehan are missing from the picture. 5 Karen Madsen Karen Madsen Karen Madsen Programs & Events During the summer, the Arnold Arboretum Education Department offers garden visits and tours, short courses in horticulture, and talks on many aspects of gardening. A selection of summer courses is shown here. For a complete catalogue of programs and events at the Atboretum, please call (617) 524-1718, ext. 162. Please note that fees shown in boldface are for members of the Arboretum. For information about becoming a member, please call (617) 524-1718, ext. 165. HOR 330 Perennial Combinations for Summer EVm Laurenzi, Garden Designer Learn how to combine perennials for complementary texture and color whether you garden in full sun or partial shade. Participants will see how to combine native plants with exotics, select plants for foliage as well as flowers, and choose plants apptopriate for a variety of sites. Cultural practices and design tech- niques for low maintenance will be discussed. Fee: $16.00, $19.00 Monday, June 20/ 10:00-noon (Case Estates) WAL 133 Private Gardens by the Sea Katherhie Alexander Field. Landscape Architect Newport, Rhode Island, has a long and romantic garden history. The former estate gardens, with their staffs of gardeners, are largely a thing of the past, but the Newport tradition of gracious garden- ing remains. Smaller gardens flourish now in the benign Newport climate. In a full day of garden vis- its, we will be escorted by Newpott-area landscape architect Kate Field, who will show us lovely pri- vate gardens, and discuss the gardening traditions of Newport, past and present. The gardens will be near the peak of bloom for roses as well as the classic palette of perennials. On one of our stops we will enjoy a picnic among the flow'ers, overlooking the sea. A special day for gar- den lovers. Fee; SI 10.00, $125.00. Fee includes transporta- tion and lunch. Friday, June 24/ 8:00 am-6:00 pm. Bus departs from the Arnold Arboretum Main Gates. Kosa rugosa ‘Salt Spray’ HOR 110 Fundamentals of Gardening Laura Eisener, Landscape Designer Whether you are a novice starting your first garden or an old hand looking for a firmer foundation, this practical course will satisfy your quest for basic gar- dening information. In the four sessions you will learn a variety of the basic principles essential to good gardening. This course will cover basic techniques of gar- dening, including: site analysis and soil preparation, irrigation, dtainage, watering, plant selection, and horticultural requirements of plants. There will be some hands-on work at the site, in addition to lectures and demonstrations. Fee: $85.00, $100.00 4 Thursdays, July 7, 14, 21, 28/ 9:00-11:30 am (Case Estates) HOR 280 History Underfoot at the Arnold Arboretum Richard Schulhof Assistant Director, Education and Public Affairs, Arnold Arboretum Although best-known for programs of botanical research and extensive collections of plants, the Arnold Arboretum with its 265-acte landscape con- tains a wealth of human and natural history. Based on historical research conducted under a recent grant from the National Endowment for the Human- ities, this class will explore the evolution of the plant collections as well as the site’s prehistory and its role in Native American, Colonial, and Country Estate periods. Wear comfortable shoes for this vig- orous rain-or-shine walk. Fee: $10.00, $12.00 Saturday, July 9/ 10:00 am-12:30 pm (Hunnewell Building and Arboretum grounds) WAL 1 10 The Blue Hills — An Author’s Perspective Thomas Palmer, Naturalist and Author o/Landscape with Reptile: Rattlesnakes in an Utban World Question: What do rattlesnakes have in common with the Blue Hills? Answer: Both have been the objects of years of fasci- nated study by author Tom Palmer. 6 Darrell Probst teaching an adult education course in perennials at the Case Estates, Weston. Explore the Blue Hills with this author and naturalist who has spent uncountable hours explor- ing the Hills in search of Crotalus horridus, the tim- ber rattlesnake. Palmer will lead a walk up his favorite peak and share his knowledge of the region’s history, ecology, geology, and folklore and perhaps introduce some of its inhabitants. (Rattle- snake sightings, however, are not likely.) The Blue Hills is a low range of hills just south of Boston. Participants should be prepared for a rig- orous walk covering one to two miles of rugged ter- rain. Bring a snack and a beverage. Participants may also wish to bring a picnic supper to enjoy after the hike. Meet at Houghton’s Pond in Milton. Direc- tions will be sent with registration confirmation. Fee; $12.00, $15.00 Sunday, July 10/ 3:00-6:30 pm (TBA) HOR 134 Summer Flowering Shrubs Paul Martin Brown, Naturalist and Horticulturist The long hot, humid days of midsummer bring a wide variety of both color and texture to the shrub border. Many genera offer unusual species that deserve consideration in the design of the summer garden. This class will focus on the culture and hab- itat requirements of a range of mid- and late-summer flowering shrubs, including Aesculus. dwarf buckeye; Yitex, chaste-rree; Buddleia, butterfly bush; Genista, dyer’s greenweed; Clethra, summer-sweet; Clerodendrum, glorybower; Calluna, heather; and many others. This is an outdoor walking course held rain or shine. Fee: $21.00, $25.00 Friday, July 29/ 9:30-noon (Dana Greenhouses) HOR 1 36 Ornamental Grasses Darrell R. Probst, Horticultural Consultant and Land- scape Designer In the diverse world of ornamental grasses exist plants suitable for gardens of every size and for sunny, shady, wet, and dry locations. Some grasses are so large and dramatic that they can be used as shrubs or specimen plantings; others are miniatures, at home in the small-scale landscape. Their colors form a rainbow of greens, pinks, creams, blues, golds, and whites. This introduction to decorative grasses will focus on the culture, management, and design potential of these versatile perennials. Saturday’s field trip will be to the Quansett Nurser- ies in Westport, MA. Fee; $48.00, $55.00 Thursday, August 18/ 6:30-8:30 pm (CE) and 1 field trip, Saturday, August 20/ 1 1:30 am-3:30 pm (TBA) 7 Amy L. C. Wilson Karen Madsen WAL 235 The Rural Landscape Marie Stella Bynies, Herb Specialist and Landscape Designer Spend a late-summer weekend enjoying a fascinat- ing look at the many ways in which farmers and craftspeople have made a living under the harsh conditions of life in western Massachusetts. In out two-day visit, we will see a wide variety of historic farms and rural work-sites, some restored to a previous era, others now serving new horticultural and agricultural uses. Hall Tavern Farm, the state's oldest privately owned tree farm. Produces farm and forestry goods such as specialty paneling and wainscoting. William Cullen Bryant Homestead, a land- scape testoted to the 1865-78 period. Includes escorted tout of the house interior. Ashfield Stone Quarry. Mica schist, formerly quarried by ancient methods, is now quarried with state-of-the-att computerized equipment. Quarriers and stone carvers will be working on the design and fabrication of garden ornaments. Kirin Farm, formerly a commercial apple orchard, established in 1820, and now the grounds and gardens of landscape designer Marie Byrnes. We will see remnants of the old orchard, along with the currently producing fruit and nut orchard. Gar- den rooms include a white moon garden, a pocket Japanese area with an ornamental pool, an herb gar- den, and a hillside planting that incorporates fmit- producing shrubs and oversized herbs. Penfrydd Farm grazes llamas, sheep, and Nor- wegian fjord horses. Colorful hand-dyed yarns and handwoven blankets are produced for sale. Wheel-View' Farm, a former dairy farm, now a bulb and cut-flower nursery. Gladiola, dahlia, canna bulbs, ismene, calla, and crinum lilies are produced for sale. Saturday lunch will be served on the grounds of one of our stops. Participants may book overnight accommodations at neatby bed-and-breakfasts. List of suggested accommodations will be sent with reg- istration confitmation. Fee includes all admissions and Saturday lunch. Fee: S75.00, $86.00 Saturday, August 27/ 10:00 am— 4:30 pm and Sunday, August 28/ 9:30 am-l:30 pm (TBA, Charlemont, MA) New Staff at the Arboretum This past January we were pleased to welcome Sheila Baskin as the Arboretum’s new secretary, whose role it is to provide support for the Public Programs, Development, and Living Collections Depart- ments. She brings several years of administrative and secretarial experience to her position. A long- time resident of Boston, Sheila enjoys working with the public and has shared her enthusiasm with many Arboretum visitors this spring. Paul Groff is the newest cutatorial assistant at Harvard University Herbaria. He came last December from Berkeley, California, where he was working as a music teacher and instrument repairman. He has recently been inserting Arnold Arboretum specimens transferred from Jamaica Plain into the Cam- bridge collection. After years spent in the West he is enjoying the seasons and the deciduous trees of Massachusetts and looks forward to Saturdays in the Arbo- retum this spring. 8 Karen Madsen Noble Allee 1 9 20 Noble Allee Sceaux. The poplars already mature, probably in the 1950s (Musee de iTle de France). end of their expected life span. A major storm in February 1990 destroyed a sufficient num- ber of the trees to force a rethinking of the planting strategy around the canal. Sceaux, after all, is not a small and private garden but a major public park that seems to host an inter- national meeting of canal joggers each evening as the sun sets. In places, Quercus robur 'Fastigiata' (upright English oak) has been planted to replace those poplars that have passed on to allee heaven. Presumably its narrow and upright form while young made it a viable choice to substitute for the Lombardy poplar. That it may acquire a pyramidal form when mature seems to have been of less concern to those responsible for new plantings. In the interest of truth-in- arboriculture these new trees have been clearly marked by signs noting that the planting is only experimental. The experiment, in fact, . has not been going well. According to Mr. Schnebelen, who is responsible for maintain- ing the park's vegetation, the oaks have taken very poorly and are, in many places, dying. No new solution has been found, and there is a possibility that in spite of their limited longev- ity, the poplars will be replanted. For the most part, the poplars around the Grand Canal have been left untouched and are pruned on an individual basis as required. Cer- tainly they have not received the constant grooming lavished on the linden allees ap- proaching and extending from the chateau. These plantings (called arbres rideaux, or "cur- tain trees") are clipped annually when in leaf, usually between May and September. What was once accomplished with ladders, clippers, and a sort of whiplike pole with a blade at its end — still to be seen in use at Vaux-le- Vicomte — is now executed with electric shears Noble Alice 21 Sceaux. Experimental planting of fastigiate oak, marked with a sign, 1992 (Marc Treib). Sceaux. The Grand Canal in 1993 (Marc Treib). 22 Noble Allee in the hands of gardeners elevated in a cherrypicker. In spite of this contemporary technology, the task remains enormous given the kilometers-long allees that structure the idea of Sceaux. The French, however, remain up to the task. At Sceaux even more than the Tuileries, the allees have received as much care as funding allows.'^ In the summer, the shade of the allees at Sceaux provides welcome relief from the long day's sun. Like blinders on a horse, they direct — or coerce — the visitor to continue moving; first to the chateau, then to the cas- cade, down to the octagonal hasin, and, of course, on to the canal. In winter the dense and intricate branch structures become sculptural forms set against the sky. In any season, how- ever, the line of the planting and the rhythm of the interval modulate the walk of those who follow the directed path. Is this, yet again, the French predilection for valuing geometry and architectonic purpose over natural growing patterns? Perhaps. But the conflict between nature and human con- struct does not create a major problem. Gar- dening practice will continue to evolve to meet the changing environmental, economic, and political conditions, whether in the use to which the park space is assigned or in the selection of species. The traditional allee will receive its care and feeding. But, again, what if one should die? In some instances, the eye will continue what nature has removed; the mind will complete the gap. The missing element can, in fact, create a syn- copation that enriches rather than detracts from the rhythm. A missing tree can actually contribute to a design, as a young tree can re- mind us of the life cycles of living organisms. And then, if one should die, you can always plant a new one. Notes ^ Androuet du Cerceau, Les Plus Excellents Bastiments de France (1576, 1579), reprint edited by David Thomson (Paris: Sand &. Conti, 1980), 220- 225. ^ The project for chateau and garden was conceived by lean-Baptiste Colbert, Secretary of State and Director of Public Works to Louis XIV, to woo the Sun King hack from his seat at Versailles. (It didn't work.) ^ For a chronology of the gardens at the Tuileries, see F. Hamilton Hazlehurst, Gardens of Illusion: The Genius of Andre Le Nostre (Nashville: Vanderbilt University Press, 1980), 167-186. Today this overlooks and forms one side of the Place de la Concorde, one of Paris' most sublime traffic carrousels. ^ Hazlehurst, 183, note 9. Hazlehurst translates what was probably sapin in the original as Norway spruce. Louis Benech suggests that the species was more likely the native Abies pectinata (silver fir). ^ See Jean-Pierre Babelon, "Les Tuileries dans I'histoire et dans la ville," 5-13, and other essays in Monuments Historiques, Les Tuileries (November 1991), No. 177. ^ In the years from 1881 to 1893 this area was recast by chateau architect Edmond Guillaume in a quasi- mirroring of the first panel of the Le Notre scheme. Thus, on the site of the demolished palace, circular beds substituted for the pools of water, and specimen planting gave the garden a slight flavor of the fashionable English and/or gardenesque manner. While a trifle discordant in taste and form, Guillaume's scheme succeeded in joining the Louvre to the Tuileries garden proper through symmetry and repetition. His task was made more difficult by the extension of Rue des Pyramides southward to the Seine as Avenue du General Lemonnier. The road effectively separated the Louvre from the gardens. * See Tanis Kmetyk, "The Politics of Gardening," Paris City (July 1993), 20-27, for a candid report of the competition, its implementation, and the politics that influenced its realization. ^ Sadly, politics reared its ugly head, in a manner characteristic of France but almost impossible to explain on any rational level. The Cribier-Benech- Roubaud scheme was truncated; Jacques Wirtz, another competition invitee, was given the design of the Cour du Carrousel. The two teams were thus forced into a marriage of inconvenience, and judging from the resulting design — the clash of competing ideologies was aggravated by the Pei terrace between them — the menage looks to be made for divorce. The reasoning behind the Wirtz Noble Allee 23 scheme is difficult to ascertain, and the relation of the radiating hedges to the embankment against which they will hump due to a level differential, appears clumsy at best. That the Tuileries will be designed in fragments is unfortunate; the opportunity to once again reunite the full sweep of the gardens has been lost. Frangois Roubaud believes that on average some fifty trees per acre are cut and replaced each year, and that as a result a considerable portion of the park's trees is actually quite young. For a historic overview of Sceaux, see Flazlehurst, 233-256. Philippe Diloe, "Sceaux," Beaux-Arts (Vol. VIII), 1931, unpaged. Hazlehurst (234-236) believes this waterproofing to have been a mistake because it may have hastened the collapse of segments of the canal's retaining wall shortly after the refurbishing. Root intrusion could have been the primary culprit, however. Russell Page, "Sceaux: A Chateau Garden," Landscape and Garden (Winter 1936), 211. Robert Riley of the University of Illinois has anointed this the Fragrant I-Beam School of Landscape Design, with trees and shrubs substituting for plywood and concrete. The Washingtonia palm is another I-beam par excel- lence, with only a small topknot of greenery to suggest that it is actually alive and growing. Like most places in the world, the maintenance budgets for the park systems of Paris and the surrounding areas have been drastically reduced. The number of gardeners tending parks like Sceaux has dropped accordingly, making even routine upkeep a challenge. Acknowledgments The author thanks Francois Roubaud and Louis Benech for discussing their work on the Tuileries,- Jean Schnebelen for explaining maintenance practice at Sceaux; and Jean-Michel Cuzin at the Musee de I'lle de France for helping to locate early photos and other documents on Sceaux. Appreciation is also due to Dorothee Imbert, who interviewed Mr. Schnebelen, helped with translations, and critically (and ruthlessly) reviewed an early version of the text. Marc Treib is professor of architecture at the University of California at Berkeley and is currently in Paris studying modern landscape architecture in Europe, 1930-1955, under the auspices of Guggenheim and Fulbright fellowships. He is the editor of Modern Landscape Architecture: A Critical Review {1993], co- author of A Guide to the Gardens of Kyoto (1980), and author of Sanctuaries of Spanish New Mexico (1993). "A Most Dangerous Tree": The Lombardy Poplar in Landscape Gardening Christina D. Wood The history of the Lombardy poplar in fashions in trees just as in all else. "The Lombardy poplar," wrote Andrew Jackson Downing in 1841, "is too well known among us to need any description."' This was an ex- traordinary thing to say about a tree that had been introduced to North America less than sixty years earlier. In that short time, this distinctive cultivar of dominating height had gained notoriety due to aggressive over- planting in the years just after its introduction. The Lombardy poplar (Populus nigra 'Italica') is a very tall, rapidly growing tree with a distinctively columnar shape, often with a buttressed base. It is a fastigiate muta- tion of a male black poplar (P. nigra}} As a member of the willow family (Salicaceae) — North American members of the genus in- clude the Eastern poplar (Populus deltoides), bigtooth aspen (Populus granditata), and quaking aspen (Populus tremuloides) — the tree prefers moist, rich soils but tolerates a wide range of conditions. Easily propagated from woody stem cuttings, it is hardy from Zone 9 to 3 and can attain its full height of one-hundred feet or more in twenty to thirty years. With a spread of only ten to fifteen feet, it presents a striking form in the landscape. The Lombardy was disseminated through- out Europe in the mid-eighteenth century from Italy, where it was found growing on the banks of the Po River in Lombardy. There was speculation in the nineteenth century that it America illustrates that there are may have originated in Persia or perhaps the Himalayan region; because the plant was not mentioned in Roman agricultural texts, writ- ers reasoned that it must have been introduced to Italy from central Asia.^ But subsequent writers have thought it more likely that the Lombardy sprang up as a mutant of the black poplar. Augustine Henry found evidence that it originated between 1700 and 1720 in Lom- bardy and spread worldwide by cuttings, reach- ing France in 1 749, England in 1 758, and North America in 1784.'* It was soon widely planted in Europe as an avenue tree, as an ornamental, and for a time, for its timber. According to at least one source, it was used in Italy to make crates for grapes until the early nineteenth century, when its wood was abandoned for this purpose in favor of that of P. nigra. The first cuttings to reach England were planted at Blenheim,^ where the cultivar can still be seen. It was the avid plant collector and landscape gardener William Hamilton who introduced the tree to North America. Documents indi- cate that his use of the tree followed practices in Great Britain and Europe. In 1788, a visitor to the Woodlands, Hamilton's showplace on the Schuylkill River west of Philadelphia, wrote that the walks were "planted on each side with the most beautiful &. curious flowers shrubs. They are in some parts enclosed with the Lombardy poplar except here &. there Lombardy Poplar 25 Lombardy poplars on Boston’s Fenway, 1919 (E. H. Wilson). openings are left to give you a view of some fine trees or beautiful prospect beyond . . One of Hamilton's own letters indicates other uses. In 1789 he referred to a flower border "in front of the necessary [privy] skreen of cedars & Lombardy poplars." The leftover poplar cut- tings were to be planted "in the Gaps long the orchard fence next the road placing them as not to exceed a foot from each other as the sea- son is so far advanced they should be planted very deep or will fail. 2 Eyes above ground will be enough."^ The first American guide to planting, published in 1806 by Philadelphia nurseryman Bernard M'Mahon, also recom- mended it as a hedge. ^ Its sheltering qualities were widely recognized, and for this purpose it was to he cut at top and sides to form a narrow green wall. "It is an excellent tree for shelter- ing or shading either fields or gardens in a flat country; hut care must he taken to plant it at a sufficient distance; and, where shelter is wanted without shade, not to introduce it on the south side of any garden or orchard, unless at a distance of at least twice its ordinary height."* Easily propagated and rapid of growth, the Lombardy quickly became exceptionally popu- lar and demand for it was high. A short thir- teen years after its introduction at the Woodlands, a nursery in Newton, Massachu- setts, devoted two full acres to its cultivation.® The next year (1798), the Prince Nursery in blushing. New York, advertised ten thousand Lombardy poplars for sale, each a height of ten to seventeen feet.'° By the early years of the nineteenth century it was said that "they infested the whole island [of Manhattan], if not most of the middle, northern, and many southern States."'^ European use of the Lomhardy as an avenue tree had not gone unnoticed in North America. John Claudius Loudon had recorded in his influential Arboretum et Fruticetum Britan- nicum of 1838 "an avenue of Lombardy pop- lars, the oldest and the highest in Germany; none of the trees are under 90 ft. high, and many of them are above 120 ft. Nothing of the kind can be more sublime."'^ In images of Boston made shortly after the turn of the nineteenth century, they can be seen lining Park Street, along the top of the Common. Americans, in a great hurry as always, prized the rapid growth that brought nearly instanta- neous shade. No doubt they were very beau- tiful while they lasted, and they offered ancillary benefits: "The elevation of the tree is also favourable for inviting and protecting singing-birds . . . Since the streets of some of the American towns have been planted with Lombardy poplars, the [Baltimore] orioles are constant visitors . . There is nothing like widespread use to uncover the weaknesses of a plant, and the Lombardy's shortcomings got ample exposure. Problems appeared shortly after the tree came into widespread use on streets. Like other members of the genus, its wood is weak and prone to break. The roots disrupt sidewalk 26 Lombardy Poplar The Lombaidies that encircled the tomb of fean- facques Rousseau at Ermenonville, France, formed one of Europe’s most famous tree plantings. The tableau was often imitated (Promenade ou itineraire des jardins d'Ermenonville fS. Girardinj, 1788). pavement above ground and penetrate and clog water and sewer pipes below ground. Boston's Park Street Lombardies were replaced by American elms as early as 1826. By 1871, an ordinance compelled the removal of existing specimens and banned the planting of new ones in Albany, New York. By then, many cities, including Washington, D.C., and Brooklyn, no longer tolerated the Lombardy.''* By mid-nineteenth century it had fallen from favor elsewhere, too. Downing, that period's chief arbiter of landscape taste and American disseminator of English practices, complained in 1841 that it had been so over- used as to become "tiresome and disgusting."'^ Another writer commented in 1870 that The 1915 caption read: “This tree has a special landscape value which no other tree possesses and under special conditions it can be used to better advantage than other trees" (Levison, American Forestry, Vol. 21). "when first introduced into this country the rage for it was so great that town streets, and country roads, and farm-house yards, were ev- erywhere filled with them; but familiarity has bred contempt."'® Just before the turn of the twentieth century, Marianna Van Rensselaer noted that "we do not see it so often, although our fathers dearly loved to plant it. It has suf- fered much from disease in recent years, and, moreover, the canons of such gardening taste as we possess say that its formality is inappro- priate in naturalistic landscape-scenes."''’ Notwithstanding reservations, it was ac- knowledged throughout the nineteenth cen- tury and into the twentieth that properly used, the tree played a significant role in the land- Lombardy Poplar 27 “A degree of sublimity" John Claudius Loudon's Arboretum et Fruticetum Britannicum, published in eight volumes over the years 1834 to 1837, remains an important compendium of centuries of information on British trees, native and introduced. In it, he gave eleven pages to the Lombardy poplar, saying, "We have been induced to enlarge on the subject more than we should have done, from seeing the frequent misapplication of the tree in the neighbourhood of London, as well as its good ef- fects in various instances."* He therefore offered several examples "to show how easy it is, by means of the Lombardy poplar, to add to the effect of a landscape, or to destroy the harmony of its different parts. In short, the Lombardy poplar, like the weeping willow and birch, is a most dangerous tree in the hands of a planter who has not considerable knowledge and good taste in the composition of landscape." Below are some of Loudon's examples. The Lombardy poplar, considered as a tall conical mass of foliage, becomes of great importance in scenery, when contrasted with round-headed trees. It is a known rule in the composition of landscape, that all horizontal lines should be balanced and sup- ported by perpendicular ones; and, hence, the bridge [at Blenheim] in figure 1, displaying a long and conspicuous horizontal line, has its effect greatly increased by the poplars planted on each side of it. Not only the lines of the bridge are balanced and supported by the upright poplars, but lengthened and pleasing reflections from the water are produced; which, breaking the horizontal gleams of light, not only produce variety and richness, but by increasing the length of the perpendicular lines formed by the poplars, confer a degree of sublimity on the picture: since it is allowed by all writers on the material sublime, from Burke to Dugald Stewart, that gradually tapering objects of great height create the emotion of sublimity. This poplar, or some equally fastigiate tree, should appear in all plantations and belts that are made with a view to picturesque effect; as in figure 2 where the outline is varied as well as the face of the plantation. Masses of round-headed trees, such as figure 3, though they might be seen to advantage in some situations, when grouping with other objects. yet, when contemplated by themselves, are quite uninteresting, from their dull and monotonous appearance; but add the poplars, as in figure 4, and you immediately create an interest and give a certain character to the group, which it did not before possess. . . . The branches of the poplars, rising stiffly upwards, contrast with, and render more graceful, the horizontal or pendant masses of the round-headed trees; and the stems of the poplars being clear of branches to a greater height than the other trees, form an agreeable variety in the lower part of the group. * Loudon, Arboietum et Fruticetum Britannicum, Vol. Ill (London: A. Spottiswoode for the Author, 1838), 1660-1670. 28 Lombardy Poplar scape. Downing recognized its beauty and the elegant effect it could produce when employed to give "life, spirit, and variety to a scene com- posed entirely of round-headed trees . . . when a tall poplar, emerging here and there from the back or centre of the group, often imparts an air of elegance and animation to the whole. In L. H. Bailey's influential Standard Cyclope- dia of Horticulture, first published in 1900, it was recommended "to give such points of em- phasis in green landscape as does the church- spire in the village."'® And the Lombardy was surely one of the plants Guy Lowell had in mind when he wrote in American Gardens in 1902: An American traveling abroad is sure, after see- ing the formal gardens of Rome and of North- ern Italy, to wish to reproduce them in some form in his own country. He does not always rememher that climatic conditions are not the same . . . different flowers, trees, and hedges have to be used in attempting to produce ef- fects similar to those in Italy, for it is impos- sible to grow here many of the broad-leaved evergreens which give so much character to the villa gardens of Rome. The lines and masses may be similar, the principles of design may he the same, but the effect in detail is different, for different elements must be used, or must needs be changed to meet new conditions.^ The resemblance of the Lombardy's narrow, aspiring head to that of the Italian cypress (Cupressus sempervirens) came in very handy in the Gilded Age when wealthy Americans acquired the taste and means to import Euro- pean models of landscaping. In an early, rela- tively modest instance, artists and writers, beginning with the sculptor Augustus Saint- Gaudens in the 1880s, transformed New Eng- land farmhouses in Cornish, New Hampshire, into versions of hillside Italian villas. A 1906 article in Century Magazine described Saint- Gaudens' use of Lombardies: Lombardy poplars have more than once been used with excellent effect by Cornish garden- ers, and, what is rarer, with reserve . . . The single poplars, which, on Mr. Saint-Gaudens's place, stand one on each comer of the terrace Cypress Alley, Villa Gamberaia, Italy, as illus- trated in An Introduction to the Study of Landscape Design by H. V. Hubbard eP Theodora Kimball, 1915. are planted solely for their architectural value. The house is rather narrow and high. These tall, slender "Lombardys" seem to belong to the scheme of the house and bring it into bet- ter proportion.^' It was in Cornish, on his own property and that of four neighbors, that the artist, archi- tect, and landscape designer Charles Platt de- veloped the Italianate villa style that played such an important part in the country house movement in turn-of-the-century America. He used the Lombardy as Italians use their cy- press, to frame views and accent architecture.^^ The poplar's susceptibility to disease has been problematic since its earliest years of cul- tivation in Europe and North America. It is prone to a canker-forming fungus that kills the tree from the top down, destroying its shape and shortening its lifespan. Cryptodiaporthe Lombardy Poplar 29 An allee of Lombardy poplars directs visitors through the entrance of an estate in Lenox, Massachusetts, 1920 (Archives of the Arnold Arboretum). canker, also known as Dothichiza canker, is one of the major diseases of poplars in general, but it affects the Lombardy most severely. Identified in the United States in 1915, the canker occurs wherever Lombardies grow, but regional conditions and the preexisting health of the individual plant appear to affect the extent of infection. No cure is known. So while the Lombardy is still grown, especially in Mediterranean climates or more northern regions, for many of us in the North- east it persists mostly as a memory. If Downing were writing today, he could no longer say that it is too well known to need description. For so many years a lead player in the cast of trees favored for landscape effect, it has become a bit player in most schemes. But its splendidly dramatic size and form en- sures a memorable impact whenever it makes an appearance. Notes ’ Andrew Jackson Downing, A Treatise on the Theory and Practice of Landscape Gardening (1841; reprint, Little Compton, R.I.; Theophrastus Pub- lishers, 1977), 154-155. ^ W. J. Bean, Trees and Shrubs Hardy in the British Isles, 8th ed. (London: John Murray, 1976), 320. Bean writes that the so-called "female Lombardy poplars" are almost certainly seedlings of typical P. nigra pollinated by "Italica," and are generally less columnar than the male parent. ^ John Claudius Loudon, Arboretum et Fruticetum Britannicum-, or. The Trees and Shrubs of Britain, 30 Lombardy Poplar Vol. Ill (London: A. Spottiswoode for the Author, 1838), 1661. * Augustine Henry, "The Black Poplars," The Gar- deners’ Chronicle (July 4, 1914) LVI, Third Series (1,436): 1-2. ^ Loudon, 1660, 1662. ^ Karen Madsen, "To Make His Country Smile: William Hamilton's Woodlands," Arnoldia (Spring 1989)49(2): 19. ^ Bernard M'Mahon, American Gardener’s Calendar (Philadelphia: B. Graves for the Author, 1806), 257. ® Loudon, 1668. ® U. P. Hedrick, A History of Horticulture in America to 1860 (NY: Oxford University Press, 1950), 146. Stephen A. Spongherg, A Reunion of Trees (Cam- bridge, MA: Harvard University Press, 1990), 80. ‘M- W. Francis. Old New York; Or Reminiscences of the Past Sixty Years (New York: Charles Roe, 1858), 23, quoted in Spongherg, 60. Loudon, Vol. I, 147. Loudon, 1666-1667, quotes The Magazine of Natural History, Vol. I, 418. '■* }. J. Levison, ed., "Ornamental and Shade Trees," American Forestry (October 1915) 21 (262): 995. Downing, 152. Frank J. Scott, The Art of Beautifying Suburban Home Grounds (NY: D. Appleton, 1870), 363. Mrs. Schuyler (Marianna) Van Rensselaer, Art Out- of -Doors (NY: Charles Scribner's Sons, 1893), 274. Downing, 152. Warren Manning, "The Art of Designing Land- scapes," The Standard Cyclopedia of Horticulture, ed. L. H. Bailey, Vol. II, 2nd ed. (NY: The Macmillan Company, 1928), 1786. Guy Lowell, Introduction, The American Garden (Boston: Bates St Guild Company, 1902), unpaged. Frances Duncan, "The Gardens of Cornish," Century Magazine (May 1906) 72: 3-19. Keith N. Morgan, Charles A. Platt: The Artist as Architect (NY: The Architectural History Foun- dation: 1985), 24-26. Morgan writes that Platt "worked broadly with existing stands of mature trees, favoring groves of birches and pines and adding Lombardy poplars for architectural accents." ^ Wayne A. Sinclair, Howard H. Lyon, and Warren T. Johnson, Diseases of Trees and Shrubs (Ithaca, NY: Cornell University Press: 1987), 184. Christina Wood is pursuing a certificate in the history of landscape design at the Radcliffe Seminars of Radcliffe College. Punctuating the Skyline: Alternatives to the Lombardy Karen Madsen Tree-experts may warn me that they are liable to borers and bark-lice, and that they lose their leaves early in the season, and in many ways invite the use of the axe. It may be so. I have enjoyed them, however for a number of years and they are entirely healthy yet, although surely a score of years in age. It will be a long time, therefore, before an axe under my direction will touch them. Even the tendency to lose their leaves early in the season would not induce me to use the axe, for their lofty spiie-like forms dominate every- thing and establish that variety of skyline so much to be desired by the lawn-planter. Let the limbs be bare and the trunk scarred and seamed with borers, the noble outline is there . . . Samuel Parsons (1891) More than a hundred years later, there remain "lawn-planters" who stand with the nineteenth- century superintendent of New York City Parks on this issue — dedicated, as he was, to the proposition that the Lomhardy poplar offers qualities not available in other trees. For these steadfast few, "the noble outline," the fast growth, sublime height, and sinuous leaf movement are irreplaceable and irresistible, more than offsetting a short life made shorter still by canker. In the face of all odds, they con- tinue to plant the Lombardy. But for those whose commitment to the problem-ridden Lombardy falls short of Mr. Parsons', there are other fastigiate trees that are worthy of consid- eration for specific situations. Populus sp. The Lombardy hadn't been long in cultivation when one special quality was noted by Wil- liam Gilpin (1791), that is, "the waving line it forms when agitated by the wind. Most trees, in this circumstance, are partially agitated: one side is in rest, while the other is in motion. But the Italian poplar waves in one simple sweep from the top to the bottom, like an ostrich feather on a lady's head." All poplars have the flattened leafstalk that makes the Lombardy's blade so responsive to the wind, and thus another poplar is a logical choice to replicate its movement and sound. Populus tremulus 'Erecta' (upright European aspen) or P. alba 'Pyramidalis' (Bolleana or fastigiate white poplar) are candidates, although not free of problems themselves. The latter can be seen on the Charles River Esplanade in Boston. Very like the Lombardy in habit (although rather wider in proportion to its height), it can be rec- ognized in summer by the cottony white of the underside of its leaves. It is easily propagated, but does not grow as fast as the Lombardy nor quite so high. Like many fastigiates, which concentrate their resources on growing upright instead of spreading, it tends to become bare at the base. Quercus robur 'Fastigiata' (Upright English Oak) Nearly all long-cultivated trees have deviated into erect -growing — as well as weeping — forms, and among them is the oak, emblem of strength and longevity. The upright English oak is large and imposing; a mature tree may be sixty feet or more in height with a span of only ten to fifteen feet. When leafless, it greatly resembles the Lombardy in form. It has the advantage of being longer-lived and freer from insect attack, although mildew can be a serious problem. Since oaks are relatively difficult to propa- gate vegetatively, cultivated specimens are generally grown from seed, which creates the possibility of wide variation in form. Most seedlings — as many as eighty or ninety percent 32 Punctuating the Skyline Populus alba ‘Pyiamidalis’ rises like a vertical spire from a horizontal line of trees on the Charles River Esplanade, Boston, giving contrast to a weeping willow and providing the exclamation point in a composition of rounded trees. All photos by the author. according to Dirr — do acquire the columnar habit of the parent. Specimens that grow true to form approach the Lombardy in outline and effect. Fagus sylvatica 'Fastigiata' (Fastigiate or Dawyck Beech) The fastigiate beech shares the grace and maj- esty of its parent species, as well as its beauty, especially when twigs take on a purplish tinge in the spring sunlight and the shapely buds have begun to expand but are still enclosed in their delicate, bronzy carapaces. It is also true to the species in its glossy foliage, smooth gray bark, and fibrous roots. The fastigiate cultivar can attain eighty feet. Dense and amenable to shearing, it makes an admirable hedge, screen, or wall. Its breadth is greater than the Lombardy's or the upright oak's, and its density gives it a bushier form than either. The fastigiate beech seen in a photo to the right is one of three that stand in a sunken garden in Boston's Back Bay. Now fifty years old, they have broadened to a pear shape; with age, side shoots tend to come off the main branches and to splay out, especially with the weight of rain. In the past few years, the lower third of these trees have been pruned. Acer rubrum 'Armstrong' (Armstrong Red Maple) Both 'Armstrong' and A. lubrum 'Columnare' are grown at the Arnold, but here it is the Armstrong that is more nearly upright. Fast growers (as much as twelve feet in five to seven years according to Dirr) and moderately weak-wooded, they can attain seventy or more feet in height, gradually spreading out over Quercus robur ‘Fastigiata’ (upright English oak) in Weston, Massachusetts. Fagus sylvatica ‘Fastigiata’ (fastigiate or Dawyk beech) on Marlborough Street, Boston. Acer rubrum ‘Armstrong’ (Armstrong red maple) at the Arnold Arboretum. Carpinus betulus ‘Columnaris’ (the Schmoo horn- beam) at the Arnold Arboretum. 34 Punctuating the Skyline Carpinus betulus ‘Columnaris’ among other Car- pinus at the Arnold Arboretum. time from an initial width of about fifteen feet. They share the early spring flowers, lovely silver-gray bark, and fall color of their species. The Armstrong serves well as an avenue tree, especially in crowded urban conditions. narrow tree is too great, the plant accepts pruning very well. However, its dense habit is by itself so neat that it looks naturally as though it had been sheared. With its impene- trable branches, the columnar hornbeam makes a superb hedge, and as a sheltering screen it is hard to beat. Its very erect branches take a slender spire-like form when young, later approaching the oval, but always very striking and elegant. Sources and References Bean, W. J. 1907. "Fastigiate Trees." The Gardeners’ Chronicle 41 (Third Series): 149-150, 184- 185, 200. 1976-1980. Trees and Shrubs Hardy in the British Isles, ed. D. L. Clarke. 8th ed. rev. 4 vols. London: John Murray. 1988. Trees and Shrubs Hardy in the British Isles, Supplement. London: John Murray. Dirr, Michael A. 1990. Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses. 4th edition., Champaign, IL: Stipes Publishing Company. Gilpin, William. 1791. Remarks on forest scenery and other woodland views (relative chiefly to picturesque beauty) illustrated by the scenes of New-Forest in Hampshire. 2 vol. London. Parsons, Samuel, Jr. 1891. Landscape Gardening. New York: G. P. Putnam's Sons. Wyman, Donald. 1965. Trees for American Gardens. Rev. and enlarged ed. New York: Macmillan Publishing Co., Inc. Carpinus betulus 'Columnaris' (Columnar Hornbeam) The sheltering qualities of the Lombardy are more than equally supplied by the columnar hornbeam (or the "Shmoo," as it is affection- ately known at the Arnold). If the height of this relatively small (forty to sixty feet) and Acknowledgements Thanks for arboricultural advice are due Phyllis Andersen, Peter Del Tredici, and Gary Roller and to Mary Jane Kaplan for literary advice. Karen Madsen is editor of Arnoldia. IN MEMORIAM Jennifer Reimer Quigley 1946-1994 It is with deep regret and sadness that we record the death of Jennifer Reimer Quigley on 30 March 1994, after a three-month battle with cancer. Known to many as Jennifer Hicks, Jennie joined the staff of the Arnold Arboretum on 29 March 1976 as Horticul- tural Secretary, a position she held until she took charge of the plants records office in March of 1979. It was in this latter position that Jennie truly found her niche at the Arboretum, a position that utilized her numerous talents and skills of organization, cartography, cal- ligraphy, and her great attention to detail. To the position she also brought her consider- able knowledge of botany and horticulture and botanical nomenclature, not to mention her great persistence in seeing enormous tasks to completion. Literally thousands of zinc records labels were created by Jennie on the now-antiquated addressograph machine, and the vast majority of records in our computer database were her entries. Jennie was also instrumental in evoking change in the fundamental ways in which the records, labeling, and mapping office operated to insure the proper curation of the Arboretum's living collections and to make information readily available to all who needed it. It was during Jennie's tenure that the Arboretum staff began the initial com- puterization of the living collections files under her direction, an attempt that was doomed by virtue of hardware failure, but one that led to the development of BG-Base and the establishment of a computer network at the Arboretum. Working as Kerry Walter's chief Arboretum consultant, Jennifer's imprint is present throughout the plant records side of BG-Base, the computer software that is now used at the Arnold Arbore- tum and at botanical gardens and arboreta worldwide. Over her eighteen years at the Arboretum Jennifer was also responsible for training and supervising a cadre of horticultural interns, many of whom have gone on to career positions at other botanical gardens and arboreta. It was a recurring and familiar event when one of these former interns would return to the Arboretum, specifically to seek out their former mentor in her basement office, which prior to the renovation of the Hunnewell Building served as the nerve center for the living collections department. While deeply involved with the curation of the woody plant collections of the Arbore- tum during working hours, Jennie spent untold time in her own garden during late after- noons and evenings and on weekends. An active member of the New England Chapter of the Rock Garden Society, Jennie served that society in various capacities including board member and chapter chairperson from 1991 to 1993. In the plant world her true love focused on small herbaceous perennials suitable for cultivation in the rock garden, and her knowledge of these plants was encyclopedic. During the winter months, more- over, Jennie's free time was usually spent reading about plants, seeking sources for new unusual ones, and coaxing seeds received from fellow enthusiasts to germinate in the warmth of her comfortable, cat-inhabited home. Ever helpful in providing needed information to both staff and the steady stream of visitors that came to study and utilize the collections at the Arboretum as well as her many friends on various computer networks, Jennifer Quigley will be sorely missed by all her friends. We have lost not only her efficiency and knowledge but also her humor, her straightforward approach to problem solving, her kindness, and her devotion to plants and the Arnold Arboretum. — S. A. Spongberg 36 Arnold Arboretum Weather Station Data — 1993 Avg. Max. Temp. (°F) Avg. Min. Temp. (°F) Avg. Temp. (°F) Max. Temp. (°F) Min. Temp. (°F) Precipi- tation (in.) Snow- fall (in.) JAN 37 21 29 59 22 2.49 8 FEB 33 14 24 47 16 4.49 7.5 MAR 41 25 33 68 24 7.08 38.8 APRIL 56 38 47 73 22 4.75 0 MAY 70 48 59 91 42 0.91 0 JUNE 79 54 67 91 40 1.73 0 JULY 85 62 74 99 49 2.49 0 AUG 80 62 71 97 52 2.81 0 SEPT 72 53 63 90 39 3.62 0 OCT 61 39 50 82 26 3.26 0 NOV 53 32 43 76 16 3.27 0 DEC 39 24 32 56 5 7.55 7.7 Average Maximum Temperature Average Minimum Temperature Average Temperature Total Precipitation Total Snowfall Warmest Temperature Coldest Temperature Date of Last Spring Frost Date of First Fall Frost Growing Season 59° 39° 49° 44.45 inches 62.0 inches 99° on July 8 5° on December 29 26° on April 8 30° on October 1 1 185 days Note: According to state climatologist R. Lautzenheiser, 1993 was very close to normal in precipitation and sun- shine. The months of May, June, July, and August were sunny, hot, and dry, creating a drought-like atmosphere at the Arboretum. The high temperature of 99° was accompanied by twenty other days in the 90's. This was seven 90° days above our normal count. September brought a reprieve with cooler temperatures and abundant moisture. This trend continued through October, November, and December, allowing our plant material to recover before the freeze of winter. Overall, there were thirty-one more growing days in 1993 than in 1992. r Summer 1994 The Magazine of the Arnold Arboretum SEP 2 0 S34 GRAY HERBARIUM amolaia Volume 54 Number 2 1994 Arnoldia (ISBN 004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Second-class postage paid at Boston, Massachusetts. Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Single copies are $5.00. All remittances must be in U.S. dollars, by check drawn on a U.S. bank, or by international money order. Send orders, remittances, change-of- address notices, and all other subscription-related communications to; Circulation Manager, Arnoldia, The Arnold Arboretum, 125 Arborway, Jamaica Plain, MA 02130-3519. Telephone 617/524-1718 Postmaster: Send address changes to; Arnoldia, Circulation Manager The Arnold Arboretum 125 Arborway Jamaica Plain, MA 02130-3519 Karen Madsen, Editor Editorial Committee Phyllis Andersen Robert E. Cook Peter Del Tredici Gary Roller Richard Schulhof Stephen A. Spongberg Arnoldia is set in Trump Mediaeval typeface and printed by the Office of the University Publisher, Harvard University. Copyright © 1994. The President and Fellows of Harvard College SEP 2 0 1994 Page 2 Welwitschia miiabilis: A Dream Come True Gillian Cooper-Driver 1 1 Mon cher ami: The Letters of Edouard Andre to Charles Sprague Sargent Phyllis Andersen 20 Considering Cotinus Kim E. Tripp 31 "A Very Valuable Shrub"; Xanthorhiza simplicissima fill Nooney 36 A Rare Chinese Tree Flowers in North America Frederick G. Meyer Front and back covers: The astonishing Welwitschia mirabilis. J. D. Hooker described it as "expanding like a dream into a huge broad woody brown disc . . . of texture and surface like an overdone loaf." This photograph (B83024‘' by Ron Testa) of the Field Museum's World of Plants diorama is used by courtesy of the Field Museum, Chicago. Inside front cover: Parc des Buttes-Chaumont, Paris, in the engraving by Blanade that served as frontis- piece to Edouard Andre's L’Art des fardins of 1879. Inside back cover: Emmenopterys henryi as drawn for The Endemic Genera of Seed Plants of China by Tsun-shen Ying, Yu-long Zhang, and David E. Boufford, published by Science Press, Beijing, 1993. Welwitschia mirabilis — A Dream Come True Gillian A. Cooper-Driver It's been said that if botanists were to invent the ideal plant for a desert environment, surely they would never come up with a monster like Welwitschia. Welwitschia mirabilis has always inspired ex- treme responses. It was the Austrian botanist and physician Dr. Friedrich Welwitsch, one of the foremost collectors of African plants, who first discovered this extraordinary plant in 1859, in southern Angola near Cape Negro. When he saw it, "he could do nothing but kneel down on the burning soil and gaze at it, half in fear lest a touch should prove it a fig- ment of the imagination" (Swinscow, 1972). In the first detailed scientific description of the plant, Joseph D. Hooker, Director of the Royal Botanic Gardens at Kew from 1866 to 1885, wrote, "it is out of the question the most won- derful plant ever brought to this country, and the very ugliest." Recent papers published on Welwitschia have used such titles as “Welwitschia — Paradox of a Parched Para- dise"; “Welwitschia, the Wonderful"; "Voyage into the impossible — I meet Welwitschia” ■, and "The ugliest plant in the world — the story of Welwitschia mirabilis. “ I myself first heard of Welwitschia mirabilis about thirty years ago from a native of the Scottish isle of Iona, a long way from the deserts of southwest Africa where this strange plant grows. As we made our way in a small boat across the ocean, my companion told me of a strange plant, halfway between a flowering plant and a conifer, which Darwin had described as '"the platypus of the plant kingdom." From that brief encounter, it had always been my ambition to see the miracle plant for myself. Welwitschia mirabilis grows naturally in only one area in the world. Its distribution is restricted to an extremely arid strip of land about seven hundred fifty miles long along the west coast of southern Africa, from the Nicolau River in Angola to the Kuiseb River in the Namib Desert of Nambia. The amount of rain in the Namib Desert varies greatly from year to year and ranges from zero to a half inch near the coast and two to four inches inland, as compared to a temperate deciduous forest, which receives approximately thirty to one hundred inches of rain a year. Welwitschia is not restricted to desert. It occupies the north- ern and central part of the Namib, but may also occur in subtropical grassland to the east and even in the Mopane Savanna (von Willert, 1985). Off the shores of southwest Africa is the Benguela Current, which flows from south to north and is extremely cold. Warm onshore winds flowing over the cold water create a belt of fog that forms on the coast at night and of- ten remains well into the morning. This con- densed moisture gives life to many lichens and to other specialized forms of insects, animals, and plants — including Welwitschia mirabilis. One of the most accessible places to see Welwitschia is in the Namib-Naukluft Park in the Welwitschia Flats between the Khan and Swakop Rivers, about thirty miles east of Swakopmund. This plain of weathered granite, quartzite, shale, limestone, and marble is Welwitschia 3 Welwitschia mirabilis in the Namib Desert. Photo by the author. home to what are probably the oldest and most dense communities of Welwitschia. As many as five to six thousand specimens have been counted in this area. It was a bright clear day, the first day in June, when I set out with two friends to find Welwitschia mirabilis. Before starting on the Welwitschia Plains Drive, it is necessary to obtain a permit and a guide pamphlet from the Ritterberg Nature Conservation Office in Swakopmund. The drive starts about three miles outside Swakopmund, a few yards from an abandoned steam engine. (This engine was imported to Namibia in 1896 to carry freight across the Namib Desert. Unfortunately, it survived only a couple of trips before grinding to a halt within sight of Swakopmund. It is named after the preacher Martin Luther, whose words, "Here I stand; God help me, I cannot do otherwise," are engraved on its ped- estal.) At the engine you turn right and drive across the Swakop River to the entrance of Welwitschia Park. The land around this part of the Swakop River is dry and at first glance entirely barren, resembling the spectacular images we have seen of the moonscape. However, closer in- spection revealed several different plants. Among the more conspicuous were two drought-resistant shrubs, the dollar bush (Zygophyllum stapfii) with round succulent leaves similar to coins and the xerophytic 4 Ainoldia 1 994 Summer inkbush (Arthraerua leubnitziae) with its tiny leaves reduced to mere scales. Others were "Inara," or Acanthosicyos horrida, and "tsamma," or Citiullis ecchirrosus. Both of these plants provide a source of water for trav- elers in the desert. Parts of the moonscape are covered with a variety of lichens in colors of orange, black, and gray-green, the most con- spicuous of which is Xanthomaculina convoluta with its bright yellow color and twisted filaments. These lichen fields, which are more extensive in the Namib than in any The natural distribution of Welwitschia mirabilis. Drawing by Clara Richardson courtesy of the Field Museum. other desert in the world, depend for their sur- vival on the condensed moisture that moves in from the sea at night. Several miles into the moonscape, a road turns off to the left to form a loop leading to Goanikontes, an old farm near the Swakop River. Here many different trees are found: the camel thorn (Acacia erioloba); anaboom or white thorn (Acacia albida), the largest acacia; Cape ebony (Euclea pseudobenus); tamarisk (Tamarix usneoides); and introduced species of Eucalyptus and Casuarina. These trees pro- vide shade from the hot sun and offer a star- tling contrast to the vegetation of the desert area. On this day in June, the farm was com- pletely deserted and silent. We left this fertile green area and returned to the moonscape. Granite cliffs, intersected with bands of black dolerite, rose on either side of the road, and then suddenly there they were, three Welwitschia plants growing up the sides of the gravel cliffs. The first sight of Welwitschia mirabilis is so totally unexpected in this bleak desert environment that it is easy to understand why Friedrich Welwitsch fell down upon his knees. Farther along the drive, the land flattens out, and more and more plants become visible. They spread across the desert, often in densely massed groups or in long lines fading away into the distance; it is rare to find a single plant all by itself. Using carbon-14 dating botanists have estimated that many of the smaller plants are thirty or forty years old, medium-sized plants a few hundred years old, and some of the larger plants are as old as fifteen hundred or even two thousand years. It is Welwitchia’s leaves that give this plant its strange appearance. It has only two perma- nent leaves. These stiff, strap-like leaves grow from a thick, almost totally submerged, woody stem and can be as much as ten feet in length. Since the leaves grow from their base, the cells at the tips are older and in time begin to turn brown and die. In the desert the leaves grow very slowly, about four to six inches per year. As the years and ultimately the centuries pass, the wind and the scouring sand split the leaves Welwitschia 5 In their natural habitat Welwitschias occur in densely distance, as can be seen in this photo by the author. longitudinally into ribbons, some ten inches or more wide, supporting Bornmann's description of the plant as looking "like a stranded octopus on a bare desert surface." Leaf-stripping also occurs when oryx antelopes feed at the leaf base (Brinckmann and von Willert, 1987) or when microarthropods graze on the undersurface of the leaves (Marsh, 1987). These leaves are unusual not only in appear- ance but also in size. Nowhere else in the Namib Desert does one see plants with such large leaves. One way for desert plants to deal with the scarcity of water is to develop ana- tomical and morphological structures that minimize water loss. For example, succulents like lithops and aloes, as well as the dollar bush mentioned earlier, have in their leaves a special central tissue that stores water (Von massed groups or in long lines fading away into the Willert et al., 1992). Other plants, such as the inkbush, cope with the desert environment by having highly reduced, leather-like leaves, which minimize the loss of water vapor. Small leaves also reduce the high leaf temperatures that the intense solar radiation of a desert environment can cause. Therefore it is para- doxical to find a plant like Welwitschia with its very large leaves growing in the middle of a desert, especially since its leaves appear not to have special water storage tissues. The leaves of Welwitschia are unusual not only in their structure, but also in their man- ner of development. The plant begins life as a winged seed. In a process similar to that of most broad-leaved flowering plants, the plant embryo first develops two primary leaves, or cotyledons. Above these and at right angles. 6 Ainoldia 1 994 Summer Welwitschia's taproot grows to massive pro- portions. It can extend downward for as much as three to five feet; the apex shown here is about four feet in diameter. Courtesy of the Field Museum (360395), Chicago. the two permanent leaves arise, and the coty- ledons wither away. Unlike all other land plants, no further leaves develop because the apical meristem (the cells from which leaves form) ceases all further activity and becomes nonfunctional. Only a pair of low crests repre- senting primordia of a second leaf pair develop. Because it generally produces only two leaves, Welwitschia has been described by Martens as "a seedling arrested in development" or as "a plant without a head." Plants use their leaves to manufacture sug- ars and other organic compounds from atmo- spheric carbon dioxide and water by the process known as photosynthesis. Carbon dioxide enters the cells of the leaf through special pores, or stomata, on the leaf surface. Water also enters and leaves the plant via sto- mata. Particularly important to plants growing in the desert is the ability to retain water and yet maintain a carbon dioxide balance so that photosynthesis can occur. Welwitschia is again unusual for a desert plant in the way it obtains its carbon dioxide for photosynthesis. In most temperate plant species, stomata remain open during the day to take carbon dioxide from the atmosphere, then close at night. But in succulents and other desert plants, the process is reversed with sto- mata remaining closed during the day to re- duce water loss and opening for water uptake at night (when atmospheric humidity is high and temperatures are low). Desert succulents also take in carbon dioxide from the atmo- sphere during the night, converting it into the organic acid malate by a process called cras- sulacean acid metabolism (CAM). During the day, when the stomata are closed, this malate provides a readily available source of carbon dioxide to allow photosynthesis to proceed in the normal way. Most succulents use CAM as a basis for their survival. It is therefore surpris- ing to learn that Welwitschia, which lives in an environment that would favor CAM, be- haves not like a succulent but like a temperate plant. Its stomata open in the morning and early evening, no organic acids accumulate during the night, and there is a marked day- time loss of water vapor from the leaves. How then does Welwitschia obtain enough water to survive? One might suppose that Welwitschia acquires its water from the mist that settles over this part of the world. Some desert plants, such as members of the crassula family, have structures called hydathodes — specialized forms of stomata — that take in wa- ter from the air. However, Welwitschia leaves do not have these structures, and it appears that its leaves cannot absorb dew or mist water. A second possibility is that the water comes from the root. Welwitschia has a large taproot that extends downward for as much as three to five feet. Depending on the soil, lateral roots move out from the taproot at various depths, and multiple branches in the roots have been observed. It is possible that suffi- cient water is somehow available in the deep- est soil layers and that Welwitschia taps into it through it deep-reaching root system. Welwitschia 7 While Welwitschia’s strangely shaped leaves apparently serve no water-gleaning function, they do help it cope with the problem of heat, which causes water evaporation. Von Willert, who has worked on Welwitschia in the Namib Desert for many years, has found that only 55% of the solar radiation is absorbed in Welwitschia’s leaves with as much as 40% being reflected away. (Compare this to most trees, from which about 25% of radiation is reflected.) Reflecting away the heat is probably the best strategy that a desert plant with large leaves can have for conserving water. Other unusual features become apparent as one inspects Welwitschia more closely. The stem has a woody appearance and a large sur- face area. From the junction of the stem and the leaves arise branches on which the repro- ductive structures (the male and female cones) can be easily differentiated. By October most of these cones are fully developed. The cones indicate that Welwitschia is a gymnosperm, related to pines and other conifers. However, a closer look at the reproductive structures reveals several features that differentiate Welwitschia completely from the conifers. A notable instance is the presence of distinct male and female "flowers." The flowers on the male plant have a single ovule, which is sur- rounded by a fused ring of "stamens" that pro- duce the pollen. Unlike the "ovule" in the female flower (as can be seen in the drawing below) the apex of the ovule in the male is ex- panded into a prominent funnel. This ovule never develops a mature seed. Instead, this sexually nonfunctional ovule may play a role in attracting pollinators as the funnel secretes a large drop of fluid precisely at the time the pollen is shed. Pollination occurs from about November to the end of March. It is still not completely clear how the pollen reaches the ovules in the female cones. One might think it was carried by the bright red and yellow insects (yellow bugs and their red larvae), Probergrothius sexpunctatus (Pyrrhocoridae), that presented a dramatic sight when we saw them in June. However, all experts agree that red beetles and their larvae are not responsible for pollination; it would appear that other insects are respon- The pollen-producing (male) inflorescences o/ Welwitschia mirabilis have numerous small "flowers” borne in the cones. The reproductive organs resemble a tiny bisexual (or hermaphodritej “flower” with a single sterile ovule (analogous to the female gynoecium in a female flower) surrounded by a fused ring of six structures (analogous to stamens). These latter structures produce the pollen. Although similar to a flowering plant, the ovule seems to be nonfunctional and never develops into a mature seed. The female “flower,” on the other hand, has an ovule but contains no traces of stamens. Drawings by Clara Richardson courtesy of the Field Museum. 8 Ainoldia 1994 Summer Cultivating Welwitschia Welwitschia was first grown successfully from seed to seed in the Botanic Gardens of the Uni- versity of Stellenbosch, and it is presently being grown with considerable success in the Montreal Botanic Gardens; the Royal Botanic Gardens at Kew; and the Huntington Gardens, San Marino. Because of the fragility of its root system, it is best cultivated from seed. Even then, however, it is notoriously difficult. Of the ten to twenty thousands of seeds produced by a female plant, only twenty to two hundred may be capable of germination (Bustard, 1990). The most critical stage is the first six months of life, as seeds collected from populations in the wild are often heavily infested with the fungus As- pergillus niger (van Jaarsveld, 1992). As described by H. Teuscher of the Montreal Botanic Gardens, growing Welwitschia is an enormously complicated business. First the seeds must be sown in very well drained pans containing granitic sand, crushed brick, and a trace of leaf mold. To ensure drainage the bot- tom of the pans should be covered with broken bits of crockery. The pans should then be cov- ered with glass and placed in filtered light at a minimum temperature of 50 degrees R The seedlings must be watered from below to avoid damping-off disease. Under these con- ditions, the seeds of Welwitschia usually ger- minate within two weeks. At five months the seedlings will have devel- oped five-to-six-inch long unbranched taproots and must be transferred to clay drainpipes or clay pots that will accommodate the long tap- root— the trickiest part of the growing process. A layer of broken crockery an inch-and-a-half deep should be placed in a twelve-inch pot with a drainpipe approximately three inches in di- ameter inserted vertically. Then the seedling is to be carefully inserted into the drainpipe, mak- ing sure the roots are fully outstretched. The drain can then be slowly filled with seedpan soil to a height of approximately three inches, followed by a mixture of one part crushed lime- stone and one part granitic sand, topped by a thin layer of crushed limestone. At this stage. the cotyledons should be lying flat along the top of the limestone. In the space between the pot and the drainpipe, two to three inches of topsoil and sand should be placed, followed by some leaf mold and a sprinkle of bonemeal and dehydrated sheep manure. Above this layer, crushed limestone and sand must be added, topped by a final layer of crushed limestone. Watering is done in the area between the drain- pipe and pot. From April to September water should be enriched with a small amount of a complete liquid fertilizer, with plain water be- ing used from the fall to the spring. Teuscher, whose method represents the con- servative end of Welwitschia culture, advises against repotting Welwitschia because of the serious hazard of damaging the root system. In- stead, every three years after the plant is estab- lished, the stone and sand mixture along with the soil between the pot and drainpipe should be removed from around the roots. Fresh soil enriched with a small dose of fertilizer should then be added. In Teuscher's experience, it takes ten to twelve years for cones to develop. Teuscher presents a daunting view of Welwitschia culture; however, others suggest that it may not be so difficult. For instance, Horwood goes so far as to say that it may not be necessary to cultivate the plants in drainpipes. Leo Song, Jr., maintains that these plants are not difficult to grow if certain basic conditions are given — full sunlight and abundant heat, protection from prolonged low temperatures, a fast draining growing medium, regular water- ing and fertilizing (preferably in a program of continuous feeding), and ample room for the root system. Song reports that he is growing Welwitschia in pumice in large pots with sub- stantial success. Van Jaarsveld also emphasizes the impor- tance of allowing sufficient space for the tap- root to develop. He attributes the success in cultivating Welwitschia at the Kirstenbosch Botanical Garden to bottom heat during the winter months, the rich, well-drained "Vanrhynsdorp" sand, and regular watering. Welwitschia 9 This model of a young Welwitschia plant shows the stout taproot and the two leathery leaves that the plant retains throughout its entire life. Courtesy of the Field Museum (B81801). sible, possibly wasps, flies, or ants, and that the ovule's fluid may act as an attractant. In- sects visit the drops of nectar secreted by the ovules in the female plants and in the process transfer pollen grains from the stamens of the male flowers. After fertilization and following the sporadic February and March rains, the seeds fill out rapidly and the female cones spread their ripe seeds from about mid-June to mid-July. On the first of June, 1994, the seeds were just being released. By October, the mature cones will have shed virtually all their seeds and next season's cones will have appeared. Welwitschia is generally classified as a gym- nosperm in the division Gnetophyta. Within this division are three orders, Ephedrales, Gnetales, and Welwitschiales, each consisting of a single family and genus. Like Welwitschia, the two other members of this division are rather unusual. Ephedra, often called Mormon tea, is a shrub-like desert genus consisting of about thirty-five species and occurring in the United States in the deserts of California, Nevada, Utah, Arizona, and New Mexico. Gnetum is a tropical genus of about thirty spe- cies found as a clinging vine in the rainforests of Asia, northern South America, the Pacific Islands, and Africa north of Namibia. But even within its own division Welwitschia is distinc- tive— unusual in its appearance, in its geo- graphical restriction, and in occurring only as a single species. Ephedra, Gnetum, and Welwitschia, as a group, are regarded as the closest living rela- tives of the flowering plants (Doyle and Donoghue, 1993). Unlike the other gymno- sperms, the Gnetophyta resemble angiosperms in having special water-conducting cells, called vessels, for increased efficiency in trans- porting water. Whether this implies a direct evolutionary relationship or is an instance of convergent evolution resulting from adapta- tion to desert environments is still a subject of some debate (Muhammad and Sattler, 1982). A possible evolutionary relationship between the Gnetophyta and the angiosperms is also suggested by certain reproductive characteris- tics, such as the unusual male "flowers" and in fertilization techniques (Gifford and Foster, 1989; Friedman, 1990). All in all Welwitschia mirabilis is an un- canny paradox. In its unique development and ambiguous relationship to the flowering plants, its very existence is a challenge to bota- nists. Certainly it was a privilege to see this living legend. Acknowledgments I would like to thank Peter Del Tredici, Assistant Director for Living Collections at the Arnold Arboretum, for his enthusiastic discussions and John Trager, Huntington Gardens, San Marino, California, for a supply of cultivated Welwitschia seeds. I would also like to thank Anthony Ashworth and Judy Butterman for accompanying me on this expedition and the Fulbright Commission for making my visit to southern Africa possible. References Bornmann, C. H. 1978. Welwitschia — Paradox of a Parched Paradise. Capetown and Johannesburg: C. Struik Publishers. Brinckmann, E., and D. J. von Willert. 1987. Injury and 10 Ainoldia 1994 Summer recovery of Welwitschia mhabilis. Dinteiia 19: 69-76. Bustard, L. 1990. The ugliest plant in the world: the story of Welwitschia mhabilis. Kew Magazine 7: 85-90. Crane, R, and C. D. Hult. 1988. Welwitschia the Wonderful. Life as a Survivor in the Desert of Southwestern Africa. Field Museum of Natural History Bulletin (February), 22-29. Craven, P., and C. Marais. 1986. Namib Flora — Swakopmund to the Giant Welwitschia via Goanikontes. Goodwood, Cape: Gamsberg, National Book Printers. Doyle, J. A., and M. I. Donoghue. 1993. Phylogenies and angiosperm diversification. Paleobiology 19: 141-167. Friedman, W. E. 1990. Double fertilization in Ephedra, a nonflowering seed plant: its bearing on the origin of angiosperms. Science 247: 951-954. Gifford, E. M., and A. S. Foster. 1989. 3rd ed. Morphology and Evolution of Vascular Plants. New York: Freeman and Co. Hooker, J. D. 1863. On Welwitschia, a new genus of Gnetaceae. Transactions of the Linnean Society of London 24: 1-48. Horwood, F. K. 1974. Succulent Safari to Africa, Part 11. Cactus and Succulent Journal (U.S.) 46: 260-261. Marsh, B. A. 1987. Micro-arthropods associated with Welwitschia mhabilis in the Namib desert Southwest Africa. South African Journal of Zoology 12: 89-96. Martens, P. 1971. Les Gnetophytes. Handbuch der Pflanzenanatomie Band 12 Teil 2. Berlin: Gerbruder Borntraeger. Muhammad, A. F., and R. Sattler. 1982. Vessel structure of Gnetum and the origin of angiosperms. American Journal of Botany 69: 1004-1021. Rowley, G. 1972. Voyage into the impossible — 1 meet Welwitschia. Journal of the Royal Horticultural Society 97: 346-350. Song, L. C. 1980. Gross morphology of developing male and female strobili of Welwitschia mhabilis Hook. f. Cactus and Succulent Journal (U.S.) 52: 30-32. Swinscow, T. D. V. 1972. Friedrich Welwitsch, 1806- 72: A centennial memoir. Botany Journal of the Linnean Society 4: 269-289. Teuscher, H. 1951. Welwitschia mhabilis. The National Horticultural Magazine 188-189. Van Jaarsveld, E. 1992. Welwitschia mirabilis in cultivation at Kirstenbosch. Veld eP Flora (December), 119-120. Von Willert, D. J. 1985. Welwitschia mhabilis — New Aspects in the Biology of an Old Plant. Advances in Botanical Research 2: 157-191. Von Willert, D. J., B. M. Eller, M. ]. A. Werger, E. Brinckmann, and H. H. Ihlenfeldt. 1992. Life Strategies of Succulents in Deserts with Special Reference to the Namib Desert. Cambridge: Cambridge University Press. Welwitsch, F. 1861. Extract from a Letter, addressed to Sir William f. Hooker, on the Botany of Benguela, Mossamedes Etc., in Western Africa. Journal of the Proceedings of the Linnean Society Botany 5: 182-187. Gillian Cooper-Driver is an Associate Professor of Plant Biochemistry at Boston University. She has just returned from spending ten months at the National University of Lesotho on a Fulbright Award. Mon cher ami: The Letters of Edouard Andre to Charles Sprague Sargent Phyllis Andersen The friendships formed by Charles Sprague Sargent over his long life were dazzling by anyone's account, international in scope, and carefully cultivated through correspondence. Letters are a biographer's lifeblood, "unpre- meditated transmitters of fact." Nothing else can convey the vitality of life as lived — the immediacy of emotions — so well as this inti- mate form of personal exchange. One of the most interesting items in the Archives of the Arnold Arboretum is a group of thirty-five letters to Charles Sprague Sargent, the found- ing director of the Arboretum, from the French landscape architect Edouard Andre (1840- 1911). The letters, written in French, date from 1886 to 1905 and include two letters from Andre's son Rene written shortly after his father's death. The Arboretum does not have copies of Sargent's half of the correspondence, but it is likely that he too wrote in French as he knew the language well enough to translate DeCars' Treatise on Pruning Forest and Orna- mental Trees (Paris, 1864) into English in 1881. Andre's letters to Sargent reflect a friend- ship based on deep professional respect and personal affection. They shared a strong inter- est in plant exploration, in taxonomy, and the newly emerging theories of landscape style in park and garden design. They exchanged seeds, plants, and books. From time to time, when Sargent visited Paris, they met. (Andre visited the United States in 1876 — as we know from his L’Art des fardins where he mentions his admiration of Boston's garden cemetery — but no documentation of a visit to Sargent has been located.) Andre was Sargent's Paris con- nection, the source and expert on all things French. Despite clear differences in personal- ity— Sargent diffident yet imperious, Andre clearly charming and gregarious — the two men were mutually supportive. They favorably re- viewed one another's books and noted each other's accomplishments in their respective publications. They shared a strong attraction to large, challenging projects and an avid curi- osity about the world. Edouard Andre is known to landscape histo- rians as a designer, an architecte-paysagiste, a visible figure in the Parisian park-building projects directed by Baron Haussmann for Na- poleon III in the last half of the nineteenth cen- tury. He is the author of a comprehensive text on garden and park design, L’Art des fardins, the designer of hundreds of private gardens and numerous public parks, a friend of Frederick Law Olmsted and of the English garden writer and designer William Robinson. In 1892 he was appointed Professor of Garden Architec- ture at L’Ecole d’ Horticulture de Versailles, the first person to hold that position. To horticulturists, Andre is known as a plantsman with strong credentials. He was a self-described botanical traveler. In 1875 he was sent by the French government on a plant- 12 Ainoldia 1994 Summer On the left, Edouard Andre in a portrait that appeared in Volume 47 (1895) of the English journal The Garden, which was dedicated to him. On the right is Charles Sprague Sargent in a portrait taken by Horace McFarland, c. 1904. The correspondence between the two was warm and mutually supportive. In a letter of 8 April 1905, Andre wrote, “I have just received your beautiful and useful volume, Manual of the Trees of North America, and I’m sending you right away my thanks and compliments, before speaking of it in the Revue Horticole. You have known for a long time how much I admire your inexhaustible creativity. ” collecting trip to South America, a trip that took two years and resulted in 3,400 speci- mens being sent back to Paris. His travels also took him to Russia, the Mediterranean, Turkey, and the United States. He amassed a personal herbarium of thousands of specimens, meticu- lously labeled and maintained. At his country home in Lacroix where he spent his summers, he developed an experimental nursery and arboretum. He was an expert on bromeliads and the genus Andrea of the Bromeliaceae was named in his honor. He published numer- ous plant profiles, articles on plant culture, and several monographs on his botanical explorations. Born in Bourges, France, the son of a nurs- eryman, Andre apprenticed for a year with the municipal horticulturist of Angers and fin- ished his education in Paris, studying for a year at the Museum d’Histoire Naturelle. In 1860, at the age of twenty, he was named head gar- dener (Jardinier Principal) of the city of Paris by Adolphe Alphand, the chief park designer for Haussmann. With this position Andre joined the team that implemented Alphand's designs, which transformed Paris from a sprawl of disconnected enclaves into a model of monumental city form that sparked interna- tional interest. The new parks and boulevards of Paris were on the itinerary of every tourist. Letters of Edouard Andre 13 Andre’s design for Sefton Park in Liverpool included a botanic garden, seen in the plan above. (From Andre’s L'Art des Jardins.j Student, and landscape professional who em- barked on the Grand Tour. Andre worked with Alphand on the Bois de Vincennes, the Bois de Bologne, and the Parc Montsouris, but his reputation today rests on his work on the Parc des Buttes-Chaumont, the crescent-shaped strip of land in the northeast quarter of Paris. It was molded from a municipal dump and gal- lows site into a park of dramatic topography, deliberate rusticity, and romantic symbolism. Andre was responsible for the planting of the site, a complex project because of the variety of environments — rock escarpments, water edges, woodland, open meadow. Andre's approach to planting design has often been compared to Olmsted's. The simi- larities are there: a reliance on rich foliage texture, a sense of appropriateness, and a sus- picion of anything decorative or overly manipulated. Like Olmsted, Andre believed that landscape improvements elevated human morals, and he used the "ill-famed" reputation of the Buttes-Chaumont site as an example. In 1866, Andre won a competition for the design of a large public park in Liverpool, England, to be built on land given to the city by Lord Sefton. Sefton Park emerged as a project of urban design not unlike those Olmsted was tackling in the United States. Andre was re- sponsible not only for the parkland but for the adjoining boulevards and building lots. The Sefton Park project, which took ten years to complete, allowed him to set up a private office in Paris, and in subsequent years of pro- fessional practice he designed parks and gar- dens all over the world. The list is staggering. It includes Woodhouse Moor Park in Leeds,- the park of Count de Friese in Friesenborg, 14 Arnoldia 1994 Summer Denmark; the garden of Count Orloff-Davidoff in Russia; the parks of Prince Liechtenstein and Baron Nathaniel de Rothschild in Austria,- as well as many private gardens in France. Andre enjoyed his wealthy clients and shared with Sargent the conviction that they alone allowed him to display his artistic aptitude. All the same, a large part of his practice was taken up with public parks. He transformed the Citadel of Luxembourg into a large public garden and the public gardens of Monte Carlo into a grand showcase of tropical plants. Sargent praised the latter gardens in a short article in Garden and Forest (April 29, 1891) for the skill and refinement with which Andre treated this important waterfront site. In Holland he managed the reconstruction of two seventeenth-century gardens, Welham and Amerongen, and their conversion into parks for the public. He worked in Rome, refin- ing plans for the Piazza Bianca and the Quirinal and working with Roman designers to transform the gardens of the Villa Borghese from a private garden into a public park. Andre also prepared plans for the redesign of Montevideo in Uruguay, predating his coun- tryman Jean-Claude Nicolas Forestier's urban design work in South America by some twenty years. The Andre letters to Sargent center on Sargent's decision to have the plates of his ten- volume Silva of North America (1890-1902), which were drawn by Charles Faxon, engraved in Paris. He requested Andre to find an en- graver and to supervise production. The details of these transactions form the heart of the let- ters. If the business details are routine, the subtext of Andre's measured diplomacy, medi- ating between a temperamental French en- graver and a demanding and parsimonious American client, makes for amusing reading. Nonetheless, Andre felt honored to assist Sargent with the project. "You also know that 1 am not insensible of the very natural feeling of pride created in me by your choice of our country to prepare the illustrations of your great work. It will soon be a century since my compatriot Andre Michaux Andre transformed the Citadel of Luxembourg into a large public garden. Part of his scheme of 1871 was a botanic garden dedicated exclusively to native flora. Andre’s idea, which he believed to be novel, was to present a complete living display of the flora of Luxembourg’s fields, woods, meadows, and crags that would acquaint the public with their names, botanical classification, uses, and ornamental qualities. (From L'Art des Jardms.j published his beautiful studies on American dendrology [North American Sylva, 1810- 1817]. 1 congratulate you on having resumed and rebuilt his work on such a grand scale, with all the resources that botanists — your compatriots and others — have accumulated over three quarters of a century, and after hav- ing made broad advances in the works of your predecessors by your personal contributions to the knowledge of North American flora" (Andre to Sargent, 2 March 1887). Andre edited L’ Illustration Florticole from 1870 to 1880 and the prestigious Revue Horticole from 1882 until his death. He was sympathetic to Sargent's tribulations as editor of Garden and Forest and contributed regular short pieces on developments in French horti- Letters of Edouard Andre 15 Edouard ANDRE AfICMiTCCTE-PArSiCiSTC «VO, Hue Chapinl, 30 U it Oc/f-cri'Le 188J LuJi <1 Sac* events The Arnold Arboretum’s Education Department offers many short courses, lectures, and programs during the winter months. These cold months give gardeners the time to plan their gardening activities for the coming season, and to learn about new plant materials and horticultural techniques. For a complete catalogue of programs and events at the Arboretum, call (617) 524-1718, ext. 162. Please note that course fees printed in boldface are for Arboretum members. JANUARY HOR 377 Woody Plant Groupings: Designing With Trees and Shrubs Laura Eisener, Landscape Designer This class will examine the ways in which woody plants can be combined to shape space in boundary plantings. The instructor will also discuss canopy layers, understory levels, groves, allees, and or- chards. The last session will emphasize ornamental pruning as a way of enhancing the effect of the tree and shrub groupings. Slides and plan drawings will be used to illustrate striking uses of woody plants. Fee: $64, $77 4 Thursdays, January 5, 12, 19, 26/ 6:30—8:30 pm (Dana Greenhouse) FEBRUARY HOR 406 Building the Design: How to Solve Problems in Landscape Construction Bob Hanss, Landscape Architect and DesignIBuild Professional This course is designed for the needs of landscape professionals, but homeowners or gardeners inter- ested in doing their own subcontracting are also welcome. The class will see slides of current or re- cently completed projects that illustrate how to deal with the many problems and issues of turning a plan into reality. Topics to be covered include cost analysis and materials selection. Fee: $54, $65 3 Wednesdays, February 1, 8, 15/ 6:30-8:30 pm (Dana Greenhouse) HOR 210 Fundamentals of Garden Design Douglas Reed, Landscape Architect Gardening begins with a plan, whether you are renovating an existing garden or starting from scratch. This course will help participants to visual- ize good garden design, get a plan down on paper, and choose plants consistent with the design. The instructor will use lectures and slides to convey the steps in developing a plan, using before- and-after slides of garden sires and the sketches that led to the final plan drawings. Students will partici- pate in weekly critiques of their plans in progress. Please note that all class members create a plan for the garden visited during the first class. Prerequisite: Some knowledge of the basics of plan drawing is needed in this course. Fee: $95, $110 1 Sunday, February 5/ 1:00—3:00 pm (Hunnewell Building and required site visit) and 5 Tuesdays, February 7, 14, 21, 28, March 7/ 6:30-8:30 HOR 277 The Business of Design Carol Julien, Garden Designer Every landscape practitioner, whether landscape architect, designer, installer, or maintenance spe- cialist, has business issues that need to be success- fully resolved. Experienced garden designer Carol Julien will introduce and discuss many of these business-related questions. Fee: $40, $46 3 Mondays, February 6, 13, 27/ 6:30—8:30 pm (Dana Greenhouse) WAL 31 1 Classic and Choice Garden Roses Stephen Scanniello, Rosarian, Brooklyn Botanic Garden As Chairman of the Heritage Rose Foundation and a judge at the International Rose Competition held each year in Paris, Stephen Scanniello sees and evaluates the best rose introductions. This beauti- fully illustrated slide lecture will give rose admirers a chance to shake the winter doldrums and plan spring purchases. Fee: $15, $18 Thursday, February 16/ 7:30-9:00 pm (Hunnewell Building) BOT 100 Introduction to Botany James Martin, Arborist and Horticultural Instructor An introduction to botany for students new to the discipline and a refresher for those who feel the need to brush up on old skills. Among the topics to be explored are plant cells and tissues, cell division, plant anatomy and morphology, plant diversity. 7 evolution, and ecology. Fee: $98, $112 6 Tuesdays, February 21, 28, March 7, 14, 21, 28/ 6:30—8:30 pm (Dana Greenhouse) HOR 458 Comparing the Viburnums in Form, Fruit, and Flower Tom Ward, Manager. Dana Greenhouses, Arnold Arboretum The viburnums offer a wide diversity of flower form, fruiting characteristics, and landscape poten- tial. Tom Ward’s talk will compare the viburnum species and cultivars in all seasons of the year and evaluate their pest and disease resistance, growth habit, and ease of cultivation. Fee: $15, $18 Thursday, February 23/ 6:30—8:30 pm (Dana Greenhouse) MARCH HOR 174 Witch Hazels: Winter Fragrance and Flowers Chris Strand. Outreach Horticulturist, Arnold Arboretum Hamamelis, better known as witch hazel, has the wonderful ability to flower in the depths of our New England winters. Different species will be in flower from the beginning of January through the end of March. Weather permitting, this course concludes with a walk through the Arboretum’s excellent witch hazel collection. Fee: $10, $12 Thursday, March 9/ 10:00 am— noon (Dana Greenhouse) WAL 330 China: Cradle of Species Diversity.^ David Boufford, Assistant Director for Collections, Harvard University Herbaria In this slide-illustrated course. Dr. Boufford will discuss his work with plant species native to China and Bhutan, presenting his views on current theo- ries of species origination in eastern Asia. Fee: $24, $28 2 Thursdays, March 23, 30/ 7:00-8:30 pm (Harvard University Herbaria) BOT118 Dwarf Conifers Richard Stomberg, Manager, Harvard University Herbaria Glasshouses Many of our common conifers have dwarf and other unusual forms. Whether they are 6-inch buns or 12-foot mops, they all add tremendous interest to our landscapes. We will also — rain or shine — walk through the Arboretum’s excellent collection of dwarf conifers. Fee: $24, $29 Saturday, March 25/ 9:30 am— 12:30 pm (Dana Greenhouse and Arnold Arboretum grounds) The Italian Garden Photographs of Charles A. Platt The Arnold Arboretum is pleased to announce an exhibit of the photographs of landscape designer Charles A. Platt (1861—1933). Platt’s 1894 pub- lication, Italian Gardens, was the first illustrated volume in English to explore Italy’s rich garden heritage, and thus influenced a generation of garden designers and landscape architects. The exhibit pre- sents many of the evocative images from this land- mark book and will be on view in the Hunnewell Building from December 1 through Eebruary 15. The Arnold Arboretum extends its many thanks to the Bank of Boston for its generous loan of this ex- hibit. For more information, please call 524-1718. Stone pines (Pinus pinea) and Italian cypress ( Cupressus sernpervirens), Villa Borghese, Rome 8 George Bairell Emerson 1 9 Seat of Benjamin Bussey, Esq., at Jamaica Plain. Oil on canvas by William A. Cobh, 1839. This landscape includes the areas of the Arnold Arboretum that have come to be known as Bussey Hill, Hemlock Hill, and the South Street Tract. South Street is plainly visible, and it is easy to see where Saw Mill Brook — now Bussey Brook — crosses it. The Bussey mansion, apparently surrounded by Lombardy poplars f'Populus nigra Ttalica’j, appears in the middle ground. Bussey had begun buying up farmsteads in 1805 and continued to do so over the next thirty years. Some of the hedgerows that delineated the separate parcels appear in the painting. On the south slope of the hill, a lilac hedge, still extant today, formed one of these bounds. This view of the Arboretum from Walk Hill, near the Forest Hills Station, remains virtually unchanged today (Archives of the Arnold Arboretum). who was one of Boston's finest trust lawyers, skilled in helping others turn their good ideas into permanently funded institutions. It was through Parker's influence that, although Arnold was convinced that an arboretum was a much needed resource, he left his will suffi- ciently indefinite to allow his trustees flexibil- ity to act. Arnold named another family friend, John James Dixwell, as the third trustee of what became the arboretum bequest. Dixwell was a prosperous merchant and president of the Massachusetts Bank. He and Emerson had long been united in their support of the Boston Society of Natural History. On his Jamaica Plain estate, on Moss Hill, Dixwell grew as many kinds of trees as he could obtain, and it was this fondness for trees that formed a bond between him and the Arnold family as well. James Arnold died in 1868. More than three years passed from the time Arnold's will was approved by the court until the trustees, Emerson, Dixwell, and Parker, signed an in- 20 Ainoldia 1 994 Fall denture with Harvard establishing the Arnold Arboretum. With an arboretum in mind, the trustees had spent the time weighing how best to carry out their duty. To turn the Arnold fund over to Harvard College, the oldest and most prestigious center of learning in New England, would be a sure way to provide for the continuance of the trust. Both Emerson and Parker were graduates, and all three had close social and professional connections with the college. Some time was spent considering the best place to locate the hoped-for arboretum. Since the trustees knew of Asa Gray's opinion that a tree collection was needed to complement the herbaceous plantings of the Harvard Botanic Garden, they pondered two sites suggested by the professor of botany. While one, the grounds around the astronomical observatory, had the advantage of proximity to the botanic garden, its size was limited. Gray also urged the use of "Brighton Meadows," a flat parcel along the Boston side of the Charles River that Henry W. Longfellow was planning to purchase and present to the college. George Emerson and the poet discussed this possibility, but another tract showed much greater promise than the Charles floodplain, the undulating, partially wooded land in what was then West Roxbury, bequeathed to Harvard by Benjamin Bussey. Bussey had left his farm and funds to the college stipulating they be used to start an in- stitution for the study of agriculture, horticul- ture, and related subjects. After his death in 1842 the property was subject to the life tenan- cies of Bussey's heirs. At the time Arnold trustees were contemplating the disposition of the fund left in their care. Harvard established the Bussey Institution, having gained the approval of Bussey's granddaughter to utilize seven acres of the West Roxbury estate. Harvard's new president, Charles Eliot, con- sulted with Emerson on the education pro- grams for the agricultural center in 1869, and after completion of the building for instruction in 1871 the Bussey Institution officially opened to students. George B. Emerson wisely surmised that using land already in possession of the college would leave the entire Arnold fund available for development of the arbore- tum. Apparently, the parties involved agreed such use of the land would be compatible with Bussey's wishes, clearing the way for a final pact to establish the arboretum on part of the Bussey property in West Roxbury. In the inden- ture, signed 29 March 1872, Emerson, Dixwell, and Parker agreed to turn the Arnold fund over to the president and fellows of Harvard Col- lege, provided the college allow some 120 acres of its Bussey estate and the income of the fund to be used for: the establishment and support of an Arbore- tum, to be called the Arnold Arboretum, which shall contain, as far as is practicable, all the trees, shrubs, and herbaceous plants, either indigenous or exotic, which can be raised in the open air at the said West Roxbury, all which shall be raised or collected as fast as is practi- cable, and each specimen thereof shall be distinctly labelled, and [for] the support of a professor, to be called the Arnold Professor, who shall have the care and management of the said Arboretum, subject to the same control by the said President and Fellows to which the professors in the Bussey Institution are now subject, and who shall teach the knowledge of trees in the University which is in the charge of the said President and Fellows, and shall give such other instmction therein as may be naturally, directly, and usefully connected therewith. And as the entire fund, increased by the accumulations above named, under the best management and with the greatest economy, is barely sufficient to accomplish the proposed object, it is expressly provided that it shall not be diminished by supplementing any other object, however meritorious or kindred in its nature. With the site and an endowment secure, establishment of the Arnold Arboretum achieved many of Emerson's and his col- leagues' objectives. Here would be a living collection to augment the "cabinet" of the Boston Society of Natural History. With one of every kind of tree and shrub, each labeled and George Barr ell Emerson 21 available for study, and arranged after Loudon's models, it would be Emerson's report come alive, a living inventory of the region's arboreal resources. Emerson kept in touch with the Arboretum during the ensuing decade. He and director Charles Sargent shared an interest in the writings of Vermont conservationist George Perkins Marsh, and Emerson urged Sargent to educate the public on the potential effects of forest destruction. One of the first efforts in this direction was publication of A Few Sug- gestions on Tree Planting (1875) in which Sargent argued for planting trees and for halt- ing the uncontrolled clearing of forests. George B. Emerson was so pleased with the pamphlet that he wrote Sargent, "If the Arboretum had never produced or would never produce any- thing else, 1 shall be richly paid for all 1 have done for it" (Arnold Arboretum Archives, G. B. Emerson correspondence, 9 March 1876). Emerson was also instrumental in Sargent's appointment as investigator on forest trees for the Department of the Interior's Tenth Cen- sus. In March 1881, when Sargent and Olmsted were at the height of their campaign to con- vince city officials to bring the Arboretum into the Boston park system, Emerson died at the Brookline home of his daughter, Lucy Lowell. In memorial tributes written upon his death, Emerson was remembered fondly for his inspi- rational leadership in the field of education and for his activities promoting the study of natural history, not the least of which was his influence on the founding of the Arnold Arboretum. References Anonymous. 1847. Reviews. A Report on the Trees and Shrubs of Massachusetts. Horticulturist 1: 565-67. Cleveland, H. W. S. 1869. The Public Grounds of Chicago: How to Give Them Character and Expression. Chicago: Charles D. Lakey. Emerson, G. B. 1846. Report on the Trees and Shrubs Growing Naturally in the Forests of Massachusetts. Boston: Commonwealth of Massachusetts. 1878. Reminiscences of an Old School Teacher. Boston: A. Mudge and Son. S. May, and T. J. Mumford. 1876. Memoir of Samual foseph May. Boston: American Unitarian Society. Loudon, }. C. 1835. Remarks on laying out public gardens and promenades. Gardener’s Magazine 11: 644-649. 1840. The Derby Arboretum. London: Longman, Orme, Brown, Green and Longmans. Morison, J. H. 1881. George Barrell Emerson, LL.D. Unitarian Review 16: 59-69. Olmsted, F. L., and T. Kimball, eds. 1973. Forty Years of Landscape Architecture: Central Park. Gambridge, MA: MIT Press. Raup, H. M. 1940. The genesis of the Arnold Arboretum. Bulletin of Popular Information, 4th series, 8: 1-11. Sargent, C. S., ed. 1889. Scientific Papers of Asa Gray. 2 vols. Boston: Houghton, Mifflin. Waterston, R. C. 1884. Memoir of George Barrell Emerson, LL.D. Cambridge, MA: John Wilson and Son. Winthrop, R. C. 1887. Tributes of the Massachusetts Historical Society to Francis E. Parker. Cambridge, MA: John Wilson and Son. Now an Arnold Arboretum Associate living in Northampton, MA, Ida Hay was on the staff of the Arnold Arboretum for over twenty years. This article is excerpted from her book, Science in the Pleasure Ground, which will be published in December by Northeastern University Press. Exploring the Complexities of Plant Hardiness J. C. Raulston and Kim E. Tripp We often use cold-hardiness ratings as the sole indicator of plant suitability for a given region. But in actuality, a much broader range of factors determines plant performance in the landscape. In the United States plant hardiness has usu- ally been interpreted as cold hardiness — the ability of a given plant to survive the winter of a given region. However, even in our most northerly regions, plant survival depends on a far broader set of environmental conditions than just those found in winter. In addition to extremes of cold temperature, survival is linked to the amount and seasonal timing of precipitation, the intensity of light, the annual cycle of daylength, the texture and fertility of soil, the consistency of temperatures, and the duration and degree of high temperatures. Cold, heat, sun, clouds, drought, flood, early frosts, late ice storms, compacted soils, chainsaw-bearing contractors — all can influ- ence a plant's hardiness. While in any region, a plant's viability de- pends on its fit with this entire range of local conditions, the relative importance of each environmental factor varies geographically. In the North, tolerance to cold usually assumes the greatest importance, whereas in the South, heat hardiness is more often the limiting fac- tor, and in most of the West, drought tolerance is the predominant influence on survival. All the same, we most often focus on cold hardi- ness, even in Florida and California, perhaps because at least superficially, winter damage is dramatically visible and easily understood: a cold front comes through tonight and tomor- row the plants are brown. This may explain why cold hardiness has been the focus of much horticultural research and evaluation effort, with far less attention paid to the other factors. Nonetheless, no prediction of a plant's viabil- ity can be accurate without considering the diverse combination of landscape conditions. Dealing With Frost: Tolerance vs Avoidance Like all forms of life, plants consist largely of water, and when temperatures drop low enough, that internal water, like all water, can freeze. Perennial plants fall into two categories based on the way they deal with frost and freezing temperatures: they can either tolerate freezing by employing a variety of physiologi- cal mechanisms; or they can avoid freezing by shedding or insulating vulnerable plant parts. Most temperate perennial plants use a combi- nation of tolerance and avoidance to survive winter's freezing temperatures, but rely prima- rily on the tolerance mechanisms (which are generally more effective for surviving long periods of freezing temperatures) to protect aboveground, persistent tissues. For example, evergreen woody plants tolerate freezing in both stems and leaves while deciduous trees avoid freezing in their leaves by dropping them and tolerate freezing only in their persistent branches and trunks. The Importance of Acclimation A frost-hardy plant's ability to get through the winter depends on the seasonal change in its metabolism to a quiescent or dormant state Plant Hardiness 23 Buxus sempervirens (boxwood) all dressed up for winter. These extreme, albeit artistic, measures protect the plants against damage from snow and ice (Peter Del Tredici). known as acclimation, which is influenced hy a variety of environmental factors. Acclima- tion is the process whereby the plant "hardens off" for winter. In order for a normally cold- hardy plant to survive the most severely cold temperatures it is genetically capable of sur- viving, it must complete the acclimation pro- cess before experiencing severe cold; otherwise it will be damaged. Similarly in the spring, as temperatures warm and days lengthen, plants need to deacclimate in order to resume active growth. There are four cases in which a plant can be damaged by freezing temperatures: 1. When temperatures fall below the plant's maximum cold-hardiness limit, even after normal acclimation has occurred; 2. When premature freezing occurs before the plant has acclimated in the fall, even if the plant is potentially able to survive those temperatures in mid- winter; 3. When unusually late freezes occur in the spring after the plant has deacclimated, even if it can survive those temperatures while it is hardened off in midwinter; and 4. When there are prolonged swings in temperature during the winter that cause the plant to deacclimate before the threat of severe freezing is over. Only the first case relates to the traditional definition of cold hardiness — the definition expressed in hardiness zone maps. In the other three cases, freezing damage occurs not be- 24 Ainoldia 1994 Fall cause the plant is located where temperatures fall helow its potential maximum cold toler- ance, hut because its stage of acclimation is out of step with the weather. If a woody plant that is normally winter hardy to -20 degrees Fahrenheit experienced such temperatures in July, it would suffer severe damage and is likely to die. However, this same plant could experience decades with those minimum winter temperatures and thrive. Mapping Cold Hardiness Hardiness zone maps generally identify areas with similar average minimum temperature ranges in which, theoretically, the same groups of plants should he viable.' But these systems have a serious limitation. They do not take into account all of the different environmental conditions that vary from re- gion to region, from soils to rainfall patterns, and this limitation causes problems. Con- sider just one example, zone 8, which en- compasses Raleigh, North Carolina,- Dallas, Texas; Phoenix, Arizona; and Seattle, Wash- ington. Then compare the plants that are grown in those areas. At least twenty-five species of palm grow in Phoenix that won't grow in Raleigh. The extremes of tempera- ture are very different even though the aver- ages lump Raleigh and Phoenix into the same zone. The same problem turns up in the hardi- ness zone maps for Europe and China that were published in Germany in the 1970s. ^ There we find Raleigh in the same zone as London. However, Raleigh has more ex- treme temperatures (especially during the summer), more variable precipitation, more frequent ice storms, less cloud cover and fog, and much higher light intensity year-round. These differences influence cold hardiness, and a given plant grown in England may be less cold hardy there than the same plant grown in Raleigh. Over an entire year, vari- ables like availability of photosynthate for growth, accumulation of storage carbohy- drates, timing of flowering and fruiting, and amount of root development as influenced by moisture availability, can influence a plant's ability to survive the winter. Clearly hardiness zones based on temperature alone cannot predict a plant's ability to survive. A better system for mapping plant adapt- ability is the one developed by Sunset Books, called the "Sunset Zones." This system, which includes Colorado and points west, presents twenty-four zones that are defined by many variables, including high and low temperatures, dry desert winds, rainfall, and other moisture (for instance, fog cover). This system is widely used in the West and has proven very helpful there. It's especially ef- fective at pinpointing microclimates, a criti- cal tool on the West Coast, where great differences occur over short distances. Los Angeles alone has nine different zones. Another excellent system is the Walter System, developed in Germany. It is based on a graphic presentation of average monthly temperatures combined with average monthly amounts and kinds of precipitation over a full year, using data collected from Walter Stations in cities all over the world. By looking, for example, at the graph for Seattle we can see not only the amount of rainfall but also the temperatures during the months of high and low rainfall. Each station graph also shows the extremes of tempera- ture recorded for the station and altitude of the station. In just one visual image the Walter System gives a much more complete picture of what the growing conditions are for that area than the temperature-based USDA zone map can give. ' See Peter Del Tredici, Ainoldia (Fall 1990) 50 (3):16-20. ^ Gerd Kriissman, Manual of Cultivated Broad-Leaved Trees and Shrubs, Vol. 1. Timber Press; 1976. Plant Hardiness 25 Why Plants Die of Cold To understand the importance of acclimation, we need to look at the process whereby plants die from the cold. There are several kinds of cold injury, but a primary cause of frost- or freeze-related death in woody plants is water freezing within the plant's cells. When water crystallizes and freezes within a cell, it rup- tures and kills the cell. If enough cells are killed, the plant will suffer significant stress and the entire organism may die. On the other hand, if freezing is restricted to water in the intercellular spaces of the plant's tissue — that is, in the spaces between the cells, outside the boundary membranes of the cells them- selves— then usually the cells are not damaged and the plant does not suffer. The cells' contents change during acclima- tion such that the concentration of solutes increases. We know that adding certain solutes to water can retard its freezing, and that the higher the concentration of these solutes, the lower the temperature required to freeze the solution — this is how antifreeze works in a car radiator. In general, the intercellular solution in a woody plant — the liquid between the cells — has a lower concentration of solutes than the solution inside the cells. This differ- ence is accentuated after acclimation, leading to more solutes in the cells. Therefore, the solution outside the cell walls freezes at a higher temperature — and earlier — than the solution inside the cell walls. Because of this differential solute concentra- tion, ice formation is restricted to the intercel- lular spaces during normal winters. If the temperature goes significantly below the plant's tolerance, however, the osmotically driven maintenance of the concentration dif- ferential between the inter- and intracellular solutions cannot be maintained; in that case, ice finally forms inside the cells, causing them I to rupture and die. ' The lesson here is that for plants to accli- mate themselves to winter, temperatures must drop during the appropriate season and at the appropriate rate. A plant of ivy (Hedera helix) that has had a chance to acclimate can survive -30 degrees Fahrenheit, but it will freeze at 25 degrees Fahrenheit if that temperature occurs in the summer during active growth. In any discussion of hardiness, it is impor- tant to remember that plants are made up of many different organs. The specific mecha- nisms of acclimation that result in freezing tolerance or avoidance vary among organs, and therefore hardiness does as well, which makes sense considering the different environments in which various plant organs occur. Roots, for example, are much less hardy than the shoots of woody temperate plants. Because of the in- sulating properties of soil, roots experience much less variation in temperature through- out the year than occurs in the air above it. This becomes an especially important consid- eration when dealing with container plants. The temperatures that containerized plant roots are exposed to are potentially much more extreme than those experienced by roots insu- lated in the soil — lower in winter and higher in summer. There can also be significant differences in hardiness even among the aboveground parts of the plant. For example, flower buds are usu- ally much less cold hardy than vegetative buds. Flere in Massachusetts you are likely to see effects of the snowline in the spring where parts of the plant below the snowline have sur- vived, be they floral or vegetative. But above the snowline, the flower buds may be killed while the vegetative buds will break and develop healthy foliage in the spring. Environmental Cues for Seasonal Acclimation The mechanisms described above — collec- tively referred to as acclimation — are triggered within the plant by environmental cues, of which the most important are seasonal changes in daylength and temperature. Differ- ences among plant species range from the purely photoperiodic in which temperature plays almost no role to those that are purely temperature-controlled with no response to photoperiod [i.e., daylength). Most plants fall somewhere between these two extremes. In 26 Ainoldia 1 994 Fall The flowering pattern of this azalea clearly demonstrates that winter’s kill line coincided with its snow line (}. C. Raulston). spring, once daylength extends beyond a cer- tain point — known as critical daylength — deacclimation is initiated in photoperiodically sensitive species, active growth is triggered, and the plant will not become quiescent again until the shortened daylengths again trigger acclimation the following fall. Because the daylengths differ throughout the year at differ- ent distances from the equator, the cues that trigger spring growth (and winter acclimation as well) in a plant of Floridian provenance will be slightly different than those for a plant of Canadian provenance. In Canada, critical daylength will be much longer than in Florida. Not only is winter longer in Canada, but also the days become much longer earlier in the spring the farther north you go. So if you moved a Florida red maple north to Canada, it might begin active growth too early in the spring and thus be subject to freezing damage. On the other hand, if you moved a Canadian red maple south to Florida, the days may never get long enough to trigger active growth in the northern plant, and the plant would never break dormancy and grow. Photoperiod responses can be influenced by artificial lights as well as by the sun. There are documented instances of delayed leaf fall in autumn on trees adjacent to streetlights, as well as premature initiation of growth on coni- fers decorated with large, nonflashing Christ- mas lights in midwinter. This is usually not a significant problem because cold temperatures generally override the influence of artificial lights. In nonphotoperiodically triggered species, temperature is the most important cue for winter acclimation. Not only absolute tern- Plant Hardiness 27 Rhododendrons on Boston’s Copley Plaza show dessication caused by sun and wind on parts of the plant not protected by snow (f. C. Raulston). peratures, but also cumulative temperatures throughout the growing season play an impor- tant role, especially when we start moving plants around the globe. Many woody plants that are native to climates with long, hot sum- mers can withstand very cold winter tempera- tures when grown in similar climates, yet if grown in climates with cooler summers and mild winters they are less cold hardy. In other words, the conditions for the previous season's growth can effect a plant's ability to withstand cold. This makes sense when we consider that growing eonditions can affect processes like photosynthesis and carbohydrate metabolism. If a plant grows in a high light environment — for example, in the American Southwest — it may be able to store much greater quantities of carbohydrate, which may improve its ability to acclimate to severe cold. If you take the same plant, however, and grow it in a lower light cli- mate, even one with a milder winter — Britain, for example — this same plant may not be able to survive that milder winter because the conditions of the previous growing season have prevented the plant from satisfying its physiological requirements for optimal winter acclimation. As a specific example, crape myrtles ( Lager stroemia indicaj are perfectly winter hardy in North Carolina where sunlight is intense, the summers are long and hot, night temperatures are high, and winter tempera- tures routinely drop to zero degrees Fahren- heit. But try to grow crape myrtles in England, where light is low and summers are cooler, and the plants will not survive winter, even though the temperature rarely falls below 10 degrees Fahrenheit. This is an example of the cumula- 28 Ainoldia 1 994 Fall tive effect of annual conditions on winter hardiness. The Significance of Provenance We tend to characterize an entire species as being of a certain degree of hardiness. Even within a species, however, individual plants adapt to the cues that are present in their spe- cific region at the critical transitional times of the year — for example, daylength, light inten- sity, cumulative temperature, or moisture con- ditions. When we move a plant to another region, we may interfere with those cues and prevent the plant from exhibiting its "normal" hardiness. Reproduction from seed is a sexual process that results in genetically variable offspring. Any population of seedlings will demonstrate an amazing array of variability. For example, a row of seedling "blue" spruces will include green, blue, and gray Picea pungens. Part of what genetic variation is about is survival. The populations of a species now found in a given region are therefore those that adapted over many thousands of years to the specific cli- mate of that region. If over a few hundred years the weather gets colder in part of a species' ter- ritory, seedlings that are more cold hardy will survive and those that aren't will be frozen out. The result, then, is a population that var- ies widely in cold hardiness from one end of its range to the other. Red maples (Acer rubrum), for example, occur in wild populations from Florida through Canada, but red maples of Floridian provenance are likely to be far less cold hardy than red maples of Canadian prov- enance. (It is important to note that the hardi- ness of a given seedling depends not on the location of the nursery where it was grown, but rather on the ancestral location of the par- ent trees from which the seed was collected.) But the combination of evolutionary genet- ics and long-term climate changes can play tricks on us. For example, there are several spe- cies of plants now found growing only in Florida that are completely cold hardy at far more northerly latitudes. During the most recent glacial era, these plants germinated suc- cessfully south of the glacial front but did not survive in glaciated areas. As a result, these species retreated southward in front of the slowly advancing glaciers. This long-term pro- cess did not cause a loss of cold hardiness in the plant's genome, which had evolved preglacially in much colder environments than those in which the surviving plants were later found. As a result, one can grow Magnolia ashei, which is now native only to the pan- handle of Florida, as far north as Chicago and Toronto. Red maples in Florida, however, are the product of continuous evolution in that region, rather than of migration from the north ahead of the glacier. Unlike M. ashei, there- fore, a Floridian red maple seedling is not likely to perform well in Chicago or Toronto. Nonetheless, conventional thinking holds that Acer rubrum is significantly more cold hardy than M. ashei. The Effects of Human Intervention on Cold Hardiness Whether a plant can thrive in a specific envi- ronment depends on the interaction of the plant with its environment. In other words, we must consider not only what the environment is doing, but also what the plant is doing. Humans often influence both elements and thereby significantly affect the cold hardiness of a given plant. It's easy to imagine how we can change the environment to influence a plant's cold hardi- ness— an extreme example would be to put it in a greenhouse — but it's harder to imagine how we can influence the plant itself to affect its hardiness. However, horticulturists can in- fluence a plant's hardiness both intentionally and unintentionally. For example, watering and fertilizing late in the season, to keep plants looking attractive or to push a second flush of growth, can lead to disaster. Compari- son at North Carolina State University of aza- leas fertilized throughout the growing season with plants fertilized only in spring demon- strated that the heavily fertilized plants looked Plant Hardiness 29 more attractive in the fall but suffered much greater winter damage and were less attractive the following spring. In another experiment, we promoted and distributed plants of a Japa- nese species of crape myrtle, Lagerstroemia fauriei, after finding it hardy to -10 degrees Fahrenheit. However, growers complained that their plants died after experiencing mini- mum winter temperatures of +10 Fahrenheit. The growers had prevented the plants from hardening off for winter by prolonging irriga- tion and fertilization into late fall in order to increase annual growth and, thereby, profit- ability. The result was that the plants went into winter with soft, nonacclimated growth that was very vulnerable to freezing damage. In effect, the plant's metabolism was affected by growing practices that created an artificial Hardiness Evaluation for the Southeastern United States Gardeners in the Northeast enjoy the ben- efits of a long tradition of plant importation and hardiness evaluation, but in the South- east there has been very little institutional evaluation of plant adaptability and perfor- mance— until recently, that is. Just seven- teen years ago, the North Carolina State University Arboretum was founded with a dual mission: determining the adaptability of new and uncommon landscape plants for use in the southeastern United States, and promoting the production and utilization of superior, adapted plants. Since 1977, the Arboretum has collected and evaluated over 9,000 plants from forty-five countries — this on only eight hard-working acres. Those eight acres currently contain over 5,000 different species and cultivars in over 450 genera. Experience has led us to believe that the only way to test a plant's adaptability is to try growing it. This method results in large numbers of killed plants, but it has also un- covered exceptional plants that perform beautifully despite very different prov- enances. We've learned as much from the deaths as from the successes. It's by studying what happened that we find indications of how the plant or the environment can be modified for future success. We retain for selection and promotion those plants of significant ornamental value that have sur- vived the various environmental stresses — and they have been many. In the years since the Arboretum was established we have ex- perienced almost every extreme of weather including the coldest temperature ever re- corded, the hottest summer, both the wet- test and the driest years, and the earliest and latest frosts. We've found wonderful surprises among both exotics and North American natives. Certainly natives have been underused and deserve greater attention and selection, but the key to the suitability of a plant lies in its adaptability, not its nativity. Many natives of the southeastern United States evolved in very specialized environments. Those from the cool, moist southern mountains often don't survive in the hot, wet summer of the Piedmont while exotics from analogous cli- mates— for instance, humid areas of Japan and Korea — have proved very useful. Since the Arboretum's mission is to en- courage the production and use of the widest possible array of plants, our distribution and advocacy program is just as important as our evaluations. We make material available to the public, to other botanical gardens, and to the nursery trade — so far over 60,000 plants of 1,000 taxa have been distributed to nurs- eries and other growers around the world, and in order to move these plants to the pub- lic quickly, growers themselves have col- lected over 2,000,000 cuttings from the plantings. 30 Arnoldia 1 994 Fall microclimate to which the plant was not adapted. It is especially easy to create microclimate effects in order to influence plant/environ- ment interactions in an urban environment. The magnolias on east-west streets in Boston's Back Bay are a case in point. Magnolias on the south-facing side of the streets reach full hloom when those on the shady north-facing side are just budding up. A late freeze would kill the blooms on the south-facing side, while the blooms on the north-facing side may be only minimally damaged. By planting early blooming plants in northern exposures or un- der higher canopies, we can minimize this kind of damage. Likewise, since a body of The winter injury to this south-facing side of a tree trunk might have been avoided by siting it in the shade or wrapping it during the winter (J. C. Raulston). water can moderate local climate considerably, planting near small water features can extend your season, just as planting near south-facing brick or stone walls can, and it shares the same potential problem — spring growth may be induced so early that the microclimate is unable to protect the new growth from severe late freezes. Just as north-facing or south-facing orienta- tion can have a major impact on plant perfor- mance, whether a plant is primarily in sun or shade can make a dramatic difference in win- ter survival and performance. This can be a particularly important consideration in pre- venting winter damage on broad-leaved ever- greens, especially the damage we call winter scorch. Plants lose water through their leaves constantly in the process of transpiration. Deciduous plants drop their leaves in the win- ter, avoiding this problem, but evergreens must contend with it year-round. Transpira- tion is increased by sunlight and wind. One of the ways this happens is that sunlight on the leaf increases the difference in temperature between the leaf surface and the air, thereby increasing water loss from the leaf. In winter, when water in the soil is frozen, it is impos- sible for the plant replace the water that is lost from the leaves, and the leaf dessicates and may die. But if it is sited in shade the plant will be more protected from the possibility of win- ter scorch. Sun scorch in winter can also occur on the south-facing side of trunks of trees. This is caused by the rapid expansion and contraction of the trunk in response to rapidly changing temperatures. Wrapping the trunk so that it is effectively shaded all winter (being sure to remove the wrap during the growing season) can help to ameliorate this problem. (Make sure to wrap from the bottom up if using a wrap of narrow width so it doesn't collect water that freezes and thaws against the trunk, damaging bark and promoting disease.) In the final analysis, the complexities of plant hardiness lie in the maze of environmen- tal conditions that both plant and gardener Plant Hardiness 31 must negotiate each year. Because these condi- tions vary so greatly, even from one neighbor- ing landscape to the next, and because humans can drastically alter the immediate growing environment of a plant, there is only one sure way to determine if an individual plant will thrive for you: you must try it in your own gar- den. To paraphrase the great English plants- man Sir Peter Smithers, 1 consider every plant hardy until 1 have killed it myself. References Alden, J., and R. K. Hermann. 1971. Aspects of cold hardiness mechanism in plants. Botanical Reviews?: 37-142. Mazur, P. 1969. Freezing injury in plants. Annual Review of Plant Physiology 20: 419-48. Li, P. H., ed. 1987. Plant Cold Hardiness. New York: Alan R. Liss. Li, P. H., and A. Sakai. 1982. Plant Cold Hardiness and Freezing Stress: Mechanisms and Crop Implications. Vol. 2. New York: Academic Press. Li, P. H., and A. Sakai. 1978. Plant Cold Hardiness and Freezing Stress: Mechanisms and Crop Implications. New York: Academic Press. J. C. Raulston is director of the North Carolina State University Arboretum and professor of horticultural science. Kim Tripp is a Putnam Fellow at the Arnold Arboretum. Previously she was curator of conifers and a postdoctoral associate at the North Carolina State University Arboretum. This article grew out of a lecture given by Dr. Raulston at the Arnold Arboretum. A Late Summer Ornamental: Poliothyrsis sinensis Stephen A. Spongbeig A handsome shrub with many desirable traits seeks a common name. Relatively few shrubs or small trees are notable for their characteristic of flowering late in the summer season and into the fall, when the ornamental attributes of most woody plants consist of their fruits and fall fo- liage color. Within the past fifteen years, how- ever, the Arnold Arboretum has received two shrubs as new introductions from China, both previously lost to cultivation, that have proved to be noteworthy, late summer-flowering orna- mentals. The so-called seven-son flower (Heptacodium miconioides) has received some attention in the horticultural press (Roller, 1986). Introduced by the 1980 Sino- American Botanical Expedition, Heptacodium has become established in the nursery trade and is now available both locally in New England from Haskell's nursery in New Bedford, Massachusetts, as well as by mail order from Wayside Gardens, Hodges, South Carolina. The second plant, Poliothyrsis sinensis, however, has not to my knowledge been heralded in the American horticultural press although English botanists and plantsmen have chronicled its history in culti- vation in the British Isles. It is so little known, moreover, that no common name has been coined for this interesting plant. This species, the sole member of the genus Poliothyrsis, belongs to the otherwise largely tropical plant family Flacourtiaceae, and the only other genus in the family grown in the Arnold Arboretum is Idesia, also represented by a solitary species, I. polycarpa. First discov- ered by Augustine Henry at the end of the last century in central China, P. sinensis was not introduced into western gardens until the leg- endary plant collector E. H. Wilson supplied the Arnold Arboretum with seeds in 1908. In- terestingly enough, these seeds were shared with botanical and horticultural institutions in Europe, where the plant has survived in cul- tivation to this day. At the Arnold Arboretum, however, established plants grown from Wilson's seed introduction were inexplicably removed from the collections in 1933. The reintroduction of the species to our collections in 1981, when seeds were received from the Shanghai Botanical Garden, has provided us with another opportunity to evaluate this plant under Massachusetts growing conditions. Two plants resulting from the seedlot from Shanghai were planted in a sunny location near the site of the old Bussey mansion. They are now multiple-stemmed shrubs approach- ing twelve feet in height, although in nature the plants apparently develop into moderate- sized trees to fifty feet in height. In habit our shrubs are rather upright, although their ulti- mate shape and height, as well as the bark of the stems, will undoubtedly change should the plants persist in our collections. Both, how- ever, have been flowering annually — com- mencing in 1990 — during late August and September. Numerous small, yellowish-white flowers are produced in moderately large inflo- rescences on the current year's growth and contrast nicely with the dark, emerald-green leaves, which are borne on reddish stalks. Indeed, it was the attractive, lustrous green Poliothyrsis sinensis 33 leaves that first drew my attention to these shrubs. And while the reddish or almost magenta-colored petiole suggested that the fall color of the leaf blades might be of a similar hue, those of our plants assume a warm yellow in late October and November. The flowers are either staminate or carpel- late (the plants are monecious) and include four to six sepals, the whorl of petals being absent. The carpellate ones develop into inter- esting capsules reminiscent in size and shape of those of the lilac. These ripen to a greenish- gray color, when the outer covering falls away to reveal the tan inner walls of the capsules. Once the outer walls have been sloughed off, the inner walls dehisce by three valves from the apex, and likewise, by three from the base. While the capsules are dissimilar in shape and substance from those of Franklinia alatamaha, the dehiscence pattern — from both the apex and base of the capsule — is shared by these otherwise unrelated genera The inflorescences of Poliothyrsis sinensis are produced on the current year’s growth in terminal corymbose racemes and contrast with the dark green leaves (Rdsz &) Debreczy). 34 Arnoldia 1994 Fall Two Poliothyrsis sinensis grown from seeds received in 1981 are now approaching a height of twelve feet (Karen Madsen). and is unknown in other woody genera culti- vated in the Arnold Arhoretum. These opened capsules, moreover, persist on the shruhs into the winter months, adding to the landscape interest of the plants during that time of year. To date, our plants from Shanghai have suf- fered no winter damage, and the fact that the original plants introduced hy Wilson persisted in the Arboretum's collections for twenty-five years suggests that Poliothyrsis is perfectly hardy in the Boston Basin. Its limits of hardi- ness and its potential as a landscape plant, however, have yet to be determined. Poliothyrsis sinensis is currently available in the North American nursery trade from Woodlanders, Inc., 1128 Collecton Avenue, Aiken, South Carolina 29801; Glasshouse- works Greenhouses, P.O. Box 97, Stewart, Ohio 45778; and Heronswood Nursery, 7530 288th Street NE, Kingston, Washington 98346. And plans have been made to propagate the plants at the Arnold Arboretum and to make them available at a future Arboretum Plant Sale. As a consequence, this interesting Chinese species, easily propagated by seed and softwood cuttings, will undoubtedly find its way into the gardens of those who enjoy growing the curious and little known — in this instance a shrub that flowers and provides landscape interest at an unlikely time of year. Initially lime green in color, the fruits mature to a light tan color before dehiscing to disclose the numerous, small, winged seeds produced within (Rdsz eP Debreczy). References Bean, W. J. Trees and Shrubs Hardy in the British Isles, 8th ed. (Ed. D. L. Clarke and Sir George Taylor), Vol. III. New York: St. Martins Press, Inc., 1976. Jeffrey, C. Poliothyrsis sinensis. Botanical Magazine (1965) N.S. 175: t. 480. Roller, G. L. Seven-Son Flower from Zhejiang: Introducing the Versatile Ornamental Shrub Heptacodium (asminoides Airy Shaw. Arnoldia (1986) 46(4): 2-14. (Note: The correct name for this species is Heptacodium miconioides Rehder.) Lancaster, R. Poliothyrsis sinensis. The Garden, Journal of the Royal Horticultural Society (1992) 117(10): 482, 483. Spongberg, S. A. Taxonomic Notes from the Arnold Arboretum. Arnoldia (1990) 50(3): 29-32. This article reports the change in name from Heptacodium jasminoides to H. miconioides. Stephen A. Spongberg, Horticultural Taxonomist at the Arnold Arboretum, was a member of the 1980 and 1986 Sino-American Botanical Expeditions to China. At the Arboretum he is responsible for the curation of the living collections. BOOK NOTES The Planters of the English Landscape Gar- den: Botany, Trees and the Georgies. Douglas D. C. Chambers. New Haven: Yale University Press for the Paul Mellon Centre for Studies in British Art., 1993. 214 pages. Hardcover. $45.00 Garden history is a young field, and like all adolescents it is struggling to free itself from familial ties, in this case the disciplines of art history and literary theory. Chambers, a pro- fessor of English at the University of Toronto, moves the field of garden history beyond the social history of patrons and the documenta- tion of careers of designers to an approach in which plants and planters — gardener, nursery- man, and amateur botanist-owner alike — take center stage. He focuses on the period from the middle of the seventeenth century to the middle of the eighteenth, when Stowe, Stourhead, Chiswick, and Rousham, the great icons of the English landscape garden, were being developed. Chambers' descriptions of the processes and materials of gardening are greatly enhanced by his familiarity with the botanical and horticultural history of the period. This was an era of extensive plant ex- ploration and importation combined with the profound scientific contribution of Linnaeus' elaboration of the principles of taxonomy. The opening essay, "The Patriots of Horti- culture," is an excellent stand-alone commen- tary on English garden theory and its relationship to classical ideas of husbandry. Chambers identifies Virgil's Georgies as the ^ aesthetic model for this new landscape. From this text he extracts classical concepts of arcadia, including the idea of rural withdrawal, i the integration of farming and gardening ("the I unity of beauty with profit and use with plea- i sure"), and the alliance of science and imagina- I tion in our understanding of nature, j Chambers also cites the influence of John I Evelyn's Silva (1664) and Dendrologia (1706) on a new generation of estate builders. Evelyn's writings encouraged a massive re- planting of English woodlands devastated by war. His motivation has been described as eco- nomic or technical, but the Silva had the un- expected effect of promoting the great wealth of trees available to the British gardener, not least the newly imported and highly valued North American species. His book inspired the planting of thousands of acres of both native and imported species, an effect that in turn required the development of new methods of transportation, planting, nursery manage- ment, and propagation. Chambers examines the writings of Stephen Switzer, Lord Shaftesbury, and others for their ideas about appropriateness in plantings in a world of expanding options. Chambers also focuses in detail on the work of Lord Petre at Thorndon Hall, his estate in Essex. Petre's plans included massive tree-planting schemes that are described as combining beauty with botany: "The landscape and the greenhouse are one continuum." Chambers' book is not unique in its focus on plants and planting techniques. Claudia Lazzaro, in her recent book, The Italian Renaissance Garden: From the Convention of Planting, Design and Ornament to the Grand Gardens of Sixteenth Century Italy (Yale University Press, 1990), places great emphasis on the contribution of plants to the architec- tural character of the Italian garden. She describes specific plants and their treatment as features in a larger composition. In her epi- logue, she reflects on the transformation of these gardens over the years due to the matu- ration of plants and the changes in mainte- nance that have been dictated by changing tastes. This is an area all too often neglected by historians and one that needs far more work to support reponsible efforts in present-day garden restoration projects. Landscape historians John Dixon Hunt and 36 Arnoldia 1994 Fall Joachim Wolschke-Bulmahn have recom- mended that garden history reach out heyond "high culture" to "lost habits of mind" to illu- minate subjects that have been relegated to the margins. Both Chambers and Lazzaro are to be commended for bypassing a traditional academic approach and revealing the rich his- tory of the planting process, a blend of craft, science, and technology. Phyllis Andersen The Greek Plant World. Hellmut Baumann. Translated and augmented by William T. Steam and Eldwyth Ruth Steam. Portland, OR: Timber Press, 1993. 252 pages,- 481 illus- trations, most in color. Hardcover. $29.95. De Causis Plantarum. Volumes 2, 3. Theophrastus. Translated and edited by Benedict Einarson and G. K. K. Link. Greek and English texts on facing pages. Cambridge: Loeb Classical Library (nos. 474 and 475), Harvard University Press. 1990. 361 and 465 pages respectively. $15.50 each For those interested in historic landscapes The Greek Plant World is a must. The author has painstakingly collected all references to plants in the writings of ancient Greeks — as well as references in works about the ancient Greeks — and assembled them in highly coher- ent and readable fashion. An excellent index makes it easy to track down what Homer, Herodotus, Plato, or Dioscorides had to say about a particular plant. It would be a great book to read before visit- ing Greece, given that most of the plants cov- ered are illustrated in sharp color photographs and are still growing there today. The armchair traveler, too, will find interest in its portraits of daily life in ancient Greece. In a related vein, it is worth noting the re- cent publication of the final two volumes of Theophrastus' great work, the two-thousand- year-old De Causis Plantarum. Remarkably, this is the first publication of Books III through VI in English. (Volume 1, encompassing Books I and II, was published in 1976 as Loeb Library no. 471.) Theophrastus, born around 370 BC, is the author of the most important botanical works that have survived from classical antiquity. He was in turn a student, collaborator, and succes- sor of Aristotle at the Lyceum. Like his prede- cessor, he was interested in all aspects of human knowledge and experience, especially natural science. His writings on plants form a counterpoint to Aristotle's zoological works. Books II and IV of De Causis Plantarum covers techniques of cultivation and agricultural methods in ancient Greece, while Books V and From The Greek Plant World. VI take up plant breeding, diseases and other causes of death, and distinctive flavors and odors. For those interested in Theophrastus, the publication of these long-awaited books is cause for celebration. After two thousand years, it might even be called the publishing event of a lifetime. Peter Del Tredici i ' " ■/ i^-"' -TV'- »toW Jr W'\ r f \ mr^ ‘^^^hs&^7 \ .' > ^ '^Bi \ r 1 WT iHIK. armldia Volume 54 Number 4 1994-1995 gray HERBARfUM MAR 1 0 1995 A Sourcebook of Cultivar Names Arnoldia (ISBN 004-2633; USPS 866-100) is published quarterly by the Arnold Arboretum of Harvard University. Second-class postage paid at Boston, Massachusetts Subscriptions are $20.00 per calendar year domestic, $25.00 foreign, payable in advance. Single copies of this issue are $10.00; copies of earlier issues are $5.00. All remittances must be in U.S. dollars, by check drawn on a U.S. bank, or by international money order. Send orders, remittances, change-of- address notices, and all other subscription-related communications to: Circulation Manager, Arnoldia, The Arnold Arboretum, 125 Arborway, Jamaica Plain, MA 02130-3519. Telephone 617/524-1718 Postmaster: Send address changes to Circulation Manager, Arnoldia The Arnold Arboretum 125 Arborway Jamaica Plain, MA 02130-3519 Karen Madsen, Editor Arthur O. Tucker, Scott G. Kunst, Freek Vrugtman, Laurence C. Hatch Page 3 Preface by Stephen A. Spongberg 5 Introduction 7 Checklist of Cultivars 29 Literature Cited 60 Index to Arnoldia, Volume 54 Cover: An assortment of leaves of Acer palmatum and japonicum as illustrated in the 1901 catalog of the Yokohama Nursery Company. From the Archives of the Arnold Arboretum Inside front cover: Frontispiece from John Parkinson's Paradisi in sole paradisus terrestris of 1629. Editorial Committee Phyllis Andersen Robert E. Cook Peter Del Tredici Gary Roller Richard Schulhof Stephen A. Spongberg Arnoldia is set in Trump Mediaeval typeface. Copyright © 1995. The President and Fellows of Harvard College Inside back cover: Varieties of Iris as illustrated in Paradisi in sole paradisus terrestris. Various roses as illustrated in Paradisi in sole paradisus terrestris by John Parkinson, 1629. Preface The process of selecting and naming cultivated plants is as old as human society itself, and the rise of civilization based on an agrarian society was in large measure dependent on the process. While plants of agricultural significance were the primary focus of atten- tion, plants of strictly ornamental value were certainly not overlooked. Consequently, by 1629 John Parkinson (1567-1650) could author the first book devoted entirely to garden plants, Paradisi in sole paradisus teiiesths, and enumerate the many variants that had been selected and perpetuated through propagation and cultivation in gardens. The tradi- tion of documenting and describing cultivars has continued since Parkinson's time and in 1753 took — along with botanical nomenclature — a new turn with the introduction by Linnaeus of binomial nomenclature. It was at this point that the polynomial or phrase names used to refer to the different types of plants were replaced by a two-word name in- corporating a generic name coupled with a specific epithet (for example, Queicus alba, our native white oak). Subsequent to the time of Linnaeus, the plants intentionally selected by growers for a particular attribute or combination of attributes were accommodated within the botani- cal system of classification and named using the infraspecific ranks of varietas and forma (e.g., Queicus robur f. fastigiata, now Q. robur 'Fastigiata'). However, because it is these same ranks that botanists use to name naturally occurring variants in the world's spon- taneous floras, ambiguity was inevitable. Did a particular varietal or forma name refer to a naturally occurring plant or to one selected for a combination of attributes and perpetu- ated only in cultivation by skilled propagators and knowledgeable gardeners? As confusion mounted, it became necessary to establish two separate systems of nomenclature: one for botanists studying forms occurring in nature, and another for hor- ticulturists selecting and naming plants for economic or ornamental value. With the pub- lication in 1953 of the first edition of the International Code of Nomenclature for Cultivated Plants (W. T. Steam, 1953, London: RHS) the term cultivar, which merged the two words "cultivated variety" into one, was officially introduced to the horticultural world, and the rules governing the naming of cultivars were formally divorced from the rules for naming botanical taxa. Henceforth, plants selected for unique attributes of hor- ticultural importance were to be given so-called "fancy" names in the vernacular (e.g.. Magnolia giandifloia 'Tulsa'), whereas botanical epithets at the species and infraspecific ranks would continue to employ names in Latin format (e.g.. Magnolia acuminata var. subcoidata). Additionally, the new "cultivated code" provided for the designation of national and international registration authorities that would serve as clearing houses for monitoring the use of cultivar names, thus insuring that their formation and application followed the recommendations of the Code. A further responsibility of registration authorities stipulated by the Code was the development of master checklists of cultivar names. This involved accounting for the 4 Ainoldia 1994-1995 Winter literature pertaining to each group or genus from the time of Philip Miller's The Garden- ers Dictionary (sixth edition, 1752) onward. The goal was to produce master checklists of cultivar names — in both Latin that predated the "cultivated code" and the vernacular — in order to stabilize cultivar nomenclature and to avoid duplication of names. At the same time, lists of known synonyms and standard references for a given group of cultivated plants would be developed. Over the years since 1953, a great deal of progress has been made in attempts to achieve these goals, and literally thousands of new cultivars have been named and introduced into the worldwide horticultural marketplace. Locating these published names in the litera- ture and finding descriptions and checklists, however, is often a daunting task for the uninitiated, and tracing elusive cultivar names frequently leads to a dead end. In providing an up-to-date listing of cultivar checklists and the widely diverse litera- ture in which cultivar names and pertinent descriptions and illustrations can be found. Professor Tucker and his coauthors have provided a great service to horticultural science as well as garden historians and landscape architects involved in historic landscape pres- ervation. This listing, moreover, gives us an indication of where we have been in the past and provides the basis for documentation of future developments in ornamental horticul- ture. The wealth of information contained in this listing is a particularly welcome sum- mary of work to date inasmuch as a new, fourth edition of the International Code of Nomenclature for Cultivated Plants is due to appear later this year. Professor Tucker and his coauthors are to be congratulated for this unique and useful contribution. Stephen A. Spongberg Horticultural Taxonomist Arnold Arboretum Introduction Gardeners have traditionally traded plants over the back fence. For many, identification beyond "grandmother's pink rose" is not needed. Others, however, want to know the cor- rect name of the cultivar (a term derived from cultivated variety). Is your old white iris Iris germanica 'Alba', or is it really 'Albicans'? An even more vexing problem is authenticating the identification of purchased plant materials from both mail-order and local nurseries. Nurseries receive plants under one name, often from a commercial grower, and are frequently slow to change. Is your 'Black Magic' iris correctly identified, or is it really 'Eleanor Roosevelt'? Have you purchased Rosa damascena 'Trigintipetala' because of its anticipated fragrance and light pink flow- ers but received instead a hybrid with no damask rose genes, dark pink flowers, and little fragrance? Correct identification of cultivars requires consultation of cultivar checklists and ultimately of period descriptions. This brings up another problem: who has published checklists of your favorite plant group? Our initial interest in compiling a list of cultivar checklists was generated by work in historical restoration. The task was to locate pre-1900 cultivars of ornamentals and to verify them by cumulative checklists (Kunst and Tucker, 1989). We have since expanded this to an attempt to locate all cultivar checklists for ornamental plants. (Because these lists are often scattered and sometimes difficult to locate, we would appreciate any cor- rections and updatings.) In the following, some historical checklists are included, but we have concentrated on the most recent, updated, cumulative ones. Our cut-off date of publication, with few exceptions, is January 1994. The ideal checklist includes the name of the cultivar, the date of introduction (or reg- istration), the name of the hybridizer, parentage, description, and colored photograph. Of course, this ideal is rarely achieved, especially in the older literature. For this reason, we have also included botanical and horticultural revisions when cultivars are described and illustrated. Good general references to extant cultivars are Harkness and D'Angelo (1986) and Hatch (1986). The Wisley Trials in the Journal and Proceedings of the Royal Horti- cultural Society are recommended for cultivar descriptions; Wright (1984) also discusses many cultivars. Besides numerous cultivars in its "Cultivar & Germplasm Releases" section, HortScience has become the vehicle for publication of cultivar names for unassigned woody genera (Huttleston, 1986, 1988, 1989, 1990, 1991, 1992, 1993; Vrugtman, 1994), genera at the Arnold Arboretum (Spongberg, 1988, 1989, 1990, 1991, 1992, 1993, 1994a), Kalmia (Jaynes, 1989), and Syringa (Vrugtman, 1988, 1989a, 1989b, 1990a, 1991, 1994b). Listings of other cultivars are supposed to be maintained by International Registration Authorities (American Association of Nurserymen, c. 1987; Leslie, 1986; Schneider, 1986a; Vrugtman, 1972, 1973, 1977, 1981, 1984, 1985, 1986, 1989c, 1990b, 1990d). These 6 Ainoldia 1994-1995 Winter designated authorities are further supplemented by cumulative checklists and origination lists maintained and published by specialist societies. The general starting point for valid publication of cultivar names is the sixth edition of Philip Miller's The Gardeners Dictionary (1752). The rules for naming cultivars are cov- ered by Brickell (1980) and Greuter (1988). The American Association of Nurserymen (c. 1987) and Allan (1988) have published guides for the public. A recent problem that may confuse efforts to stabilize cultivar names is the substitu- tion of trademarks. The statement by the AAN that "under Federal law, plant variety (cul- tivar) names may not be trademarked" actually runs counter to the current practice in some large wholesale North American nurseries. For example, many horticulturists know the trademarked name Ilex China Girl™ but have never heard of 'Mesog', its regis- tered cultivar name. Even the prestigious Modern Roses 10 (Cairns, 1993) does not list 'Wilwind', the cultivar name, but rather Windmill™. What, then, is the real cultivar name? The Townsend-Purnell Plant Patent Act of 1930 provides a 17-year patent protection for asexually propagated cultivars, and the Plant Variety Protection Act of 1980 provides 18-year legal protection for sexually propagated cultivars in the United States. In order to circumvent this limitation of time, some nurseries have resorted to trademark names (Chadwick, 1988; Darke, 1991, 1992; Dates and Luby, 1988; E. McClintock, personal com- munication, 1990; Royon, 1986). While this is allowed by the International Code of Nomenclature for Cultivated Plants (Brickell, 1980), with this practice different cultivars may be substituted under the same trademark name from year to year. Although we understand the monetary reason for using trademark names, we must chastise the nurs- ery industry for creating a vast confusion in the process, and no solution is envisioned for the immediate future. Ultimately, after having spent good money for 'Munstead' lavender because of its asso- ciation with Gertude Jekyll, it is disappointing to consult the checklists and realize that you have really purchased 'Compacta'. Errant nursery cataloguers will only be corrected by gardeners who insist on correct labelling for their money. Arthur O. Tucker Department of Agriculture and Natural Resources Delaware State University Dover, DE 19901-2277 U.S.A. Scott G. Kunst 536 Third St. Ann Arbor, MI 48103 U.S.A. Freek Vrugtman Royal Botanical Gardens Box 399 Hamilton, Ontario L8H 3H8 Canada Laurence C. Hatch P. O. Box 12011 Raleigh, NC 27605 U.S.A. Checklist of Cultivars Abies See conifers. Acacia See Australian & South African plants. Acer Cultivars of maples are listed by Bean (1970-1988), Bom (1982), Grootendorst (1969a), Harris (1983), Kriissmannn (1984-1986), Mulligan (1958), Murray (1970), Schwerin (1919), and Weaver (1976b). The cultivars of the vine maple [A. ciicinatum Pursh) are discussed by Vertrees (1979). Cultivars of red maple {A. rubrum L.), sugar maple [A. sacchaium Marsh.), Norway maple [A. platanoides L.), and silver maple (A. saccharinum L.) are listed by Santamour & McArdle (1982a, 1982b, 1982c, 1982d). The cultivars of Japanese maple [A. palmatum Thunb.) are thoroughly documented by Harris (1982) and Vertrees (1978, 1987) with color photographs. Additional recent registrations are recorded in Huttleston (1986, 1989). Achimenes See Gesneriaceae. Aconitum Some of the cultivars of the monkshoods are listed by Lord (1988) and Mussel (1986). Adiantum See ferns. Adonis Cultivars of Adonis amurensis Regel &. Radde are discussed by Nakamura (1964). Aeschynanthus See Gesneriaceae. Aesculus The cultivars of the horsechestnuts are discussed by Bean (1970-1988), Grootendorst (1967a), Krussmannn (1984-1986), and Wright (1985). Agonis See Australian & South African plants. Agapanthus The cultivars of the Nile lilies are discussed in the Wisley Trials of 1977 (Royal Horticultural Society, 1978). Aglaonema The cultivars of the Chinese evergreens are listed by Jervis (1980). Allium The few ornamental cultivars of Allium, the onions, are listed by Davies (1992). Alnus Cultivars of the alders are listed by Ashburner (1986) but without introduction dates or background. Grootendorst (1972a) and Schneider (1965a) also discuss the cultivars of alders. An additional registration of Alnus is recorded by Huttleston (1988). Cultivars of Alnus are also discussed by Bean (1970-1988) and Kriissmann (1984-1986). Aloe The South African Aloe Breeders Association has circulated an unpublished list of Aloe cultivars (for example, 1987), and many cultivars are published in Aloe and other South African journals. Alsobia See Gesneriaceae. Alyssum The cultivars of the alyssums are discussed by Dudley (1966). Amaryllidaceae Traub & Hannibal (1960) list the cultivars of Bmnsvigia with later additions published in Plant Life. Traub (1961) lists the cultivars of x Crinodonna with later additions in Plant Life. Kelsey St Dayton (1942) and Anonymous (1958f) are the first to list the cultivars of the garden amaryllis, Hippeastium, but the most comprehensive list is by Traub et al. (1964) with subsequent registrations in Plant Life. The nerines are listed by Kelsey Dayton (1942), 8 Ainoldia 1994-1995 Winter the Royal General Bulbgrowers' Association (1991), and Smithers (1993), but the most compre- hensive lists are Menninger (1960), Roberts (1984), and Smee (1984) with later additions in editions of Plant Life. Amelanchier A checklist of ornamental and fruiting shadbush cultivars is Hilton (1982, 1984). Krtissmann (1984-1986) also lists cultivars. Anigozanthos See Australian &. South African plants. Anemone Many cultivars of Anemone are listed by Trehane (1989). The cultivars of A. nemorosa L. are listed by the Royal General Bulbgrowers' Association (1991) and Toubol (1981). The history and performance of cultivars of Anemone japonica (Thunb.) Sieb. St Zucc. are discussed by Clausen (1972a) and Hensen (1968, 1979). Antirrhinum The cultivars and performance of the snapdragons are listed by the Royal Horticul- tural Society (1913b). Arctostaphylos The cultivars of the bearberries and manzanitas are recorded by Keeley St Keeley (1994). Ardisia The Japanese cultivars of Aidisia japonica (Hornst.) Blume, the marlberry, are discussed by YingerStHahn(1985). Argyranthemum The cultivars of the marguerite are compared and contrasted with studio photographs by Cheek (1993). Aster The most comprehensive lists of the cultivars of the asters are by Meier (1973a, 1973b, 1973c, 1973d) and Jensma (1989); the latter is being expanded and revised. Kelsey St Dayton (1942), Royal Horticultural Society (1902, 1908a, 1926a), and Trehane (1989) discuss the cultivars of the hardy asters, but these are published without introduction dates or background. Ranson (1946) lists mostly species with few cultivars. The history and performance of cultivars of the asters are discussed by Allen (1983), Clausen (1973a), and Jelitto St Schacht (1990). Barret (1959) discusses the perfor- mance of cultivars of A. ericoides L. Astartea See Australian St South African plants. Astilbe The most comprehensive published list of Astilbe cultivars is levinya St Lusinya (1975) with c. 170 cultivars, detailed descriptions of c. 50, and an extensive bibliography. Hensen (1969) discusses the history and performance of species and cultivars of Astilbe. Jelitto St Schacht (1990), the Royal Horticultural Society (1970b), Schneider (1968), and Trehane (1989) also list cultivars of Astilbe. Aubrieta The cultivars of A. columnae Cuss., A. deltoidea (L.) DC., and A. intermedia Heldr. St Orph. are thoroughly discussed by Clausen (1973c) and Hensen (1976). Jelitto St Schacht (1990) and Trehane (1989) also list cultivars of Aubrieta. Australian & South African plants The Australian Cultivar Registration Authority has circulated a continually updated list (for example, 1988) of registered cultivars of Acacia, Agonis, Anigozanthos, Astartea, Baeckea, Banksia, Baura, Blechnum, Boronia, Brachychiton, Brachycome, Callistemon, Callitris, Ceratopetalum, Chamelaucium, Correa, Crowea, Epacris, Eremophila, Eriostemon, Eucalyptus, Eucryphia, Grevillea, Hakea, Hardenbergia, Helichrysum, Hypocalymma, Kennedia, Kunzea, Lechenaultia, Leptospermum, Lophostemon, Melaleuca, Myoporum, Pandorea, Pimelea, Plectranthus, Piostantheia, Pultenaea, Scaevola, Spyiidium, Telopea, and Tetiatheca. Checklist of Cultivais 9 Baeckea See Australian St South African plants. Banksia See Australian & South African plants and Proteaceae. Baura See Australian & South African plants. Begonia The most comprehensive checklist of begonias is Ingles (1990). This should be supplemented with Kelsey &. Dayton (1942), Thompson (1976-1978, 1984), and Thompson Thompson (1980, 1982). Cultivars of B. semperfloiens-cultorum hybrids are published by Maatsch (1962), Maatsch St Nolting (1969, 1971a), and Nolting St Zimmer (1975a, 1980a, 1985, 1987). Cultivars of tuberous begonias are listed by Haegeman (1978, 1979) and Langdon (1969). Cultivars of other begonias are published by the American Begonia Society (1957, 1958, 1962, 1967, 1985). Registrations in The Begonian are summarized by Vrugtman (1972). These should be used in conjunction with Japan Begonia Society (1980), Misono (c. 1974-1978), and Thompson St Thompson (1981). Berberis Schneider (1923) covers the publication history and descriptions of cultivars of the barberries. The cultivars of the barberries are also listed by Ahrendt (1942, 1949, 1961), Krussmann (1984-1986), Laar (1972), and Wyman (1962b). Bergenia The cultivars of the bergenias are discussed by Beckett (1983), Laar (1973), and Yeo (1971a, b). Betula Cultivars of the birches are listed by Ashburner (1980), Fontaine (1970a), Grootendorst (1973a), Jong (1986), Santamour St McArdle (1989), and Wyman (1962c). Cultivars of Betula are also discussed by Bean (1970-1988) and Krussmann (1984-1986). Blechnum See ferns. Boronia See Australian St South African plants. Bougainvillea The most comprehensive discussions of cultivars of bougainvillea are Choudhury St Singh (1981) and MacDaniels (1981). Previous checklists are Anonymous (1959c) and Gillis (1976). Subsequent registrations are recorded by Singh (1986). Brachychiton See Australian St South African plants. Bracbycome See Australian St South African plants. Bromeliaceae A preliminary checklist of bromeliad cultivars has been prepared by Beadle (1991) and the Bromeliad Society (1989). Brunsvigia See Amaryllidaceae. Bucinellina See Gesneriaceae. Buddleja The cultivars of the butterfly bushes are listed by Leeuwenberg (1979) but without dates of introduction or hybridizers. Gultivars of the butterfly bushes are also discussed by Bean (1970-1988), Grootendorst (1972b), and Krussmann (1984-1986). Bulbs The cultivars of many hardy and tender bulbs are published by the Royal General Bulb- growers' Association (most recent is 1991). Many cultivars are also listed in Trehane (1989). Buxus A guide for registration and documentation of cultivar names of Buxus is provided by Dudley Eisenbeiss (1971). The cultivars of boxwood are listed by Bean (1970-1988), Batdorf (1987, 1988), Krussmann (1984-1986), and Wagenknecht (1965, 1967, 1971, 1972). Cactaceae Cultivars of many succulents, including cacti, are listed by Jacobsen (1977). The cultivars of Epiphyllum, the orchid cacti, are thoroughly discussed by Rainbow Gardens (1979), along with cultivars of Epiphyllum x Apoiocactus. This should be supplemented with 10 Arnoldia 1994-1995 Winter Hashizume (c. 1982-1985), who provides good color photographs and English captions in his guide to taxa of Epiphyllum; additional color photographs are presented hy Leue (c. 1987). The cultivars of Schlumbeigera are discussed by Horobin (1985). Caladium The cultivars of the caladiums are evaluated for landscaping by Wilfret (1984). Callistemon See Australian & South African plants. Callistephus The cultivars of the China aster, C. chinensis (L.) Nees, are assembled into check- lists by Maatsch (1958, 1964), Maatsch St Nolting (1971c), Nolting St Zimmer (1975c, 1981, 1987), and Olmsted et al. (1923). Callitris See Australian St South African plants. Calluna A guide to naming heather cultivars is McClintock (1986). Bean (1970-1988), Chappie (1951), Johnson (1956), Kriissmann (1984-1986), Laar (1968, 1970a, 1974, 1977a), Letts (1966), Proudley St Proudley (1974), and Underhill (1990) list many cultivars of heathers. Munson (1981, 1984) provides a comprehensive key to the species and cultivars of Calluna with full botanical descriptions in the 1981 thesis. Camellia Bean (1970-1988), Durrant (1982), Erdman (1949), Gerbing (1945), Hertrich (1954-1959), Hume (1955), Kriissmann (1984-1986), Macoboy (1981), and Sharp (1957) list many cultivars of camellias, but Woodroff St Donnan (1990) is probably the best compact checklist, while Savige (1993) is probably the most complete list with 41,000 cultivars. The Japanese cultivars of camellias are listed by Tuyama (1968), while the Chinese cultivars are listed by the Kunming Institute of Botany, Academica Sinica (1986). The International Camellia Society expects to publish the International Camellia Register. Campanula The history and performance of cultivars of the bellflowers are discussed by Clausen (1976) and Lewis & Lynch (1989). Trehane (1989) also lists the cultivars of the bellflowers. Canna Kelsey Dayton (1942) has published a list of canna cultivars without dates and hybridiz- ers. Additional information is given by the Royal General Bulbgrowers' Association (1991), Royal Horticultural Society (1908b, 1909), and Trehane (1989). Mukherjee St Khoshoo (1970) provide botanical characteristics of many cultivars. Capsicum The peppers are sometimes grown as ornamentals (e.g.. Tips'), and Andrews (1984) records extensive information on these cultivars in her monumental book. Carnivorous plants Named cultivars of Dioseia, Nepenthes, and Sanacenia are listed by Schlauer (1986, 1987; note that the first list neglects to capitalize the cultivars) and Kusakabe (1987). Additional cultivars of Sanacenia are later listed by Mellichamp St Gardner (1987). The hybrids of Nepenthes are reported by Fleming (1979). Fleming's list is reprinted in Pietropaolo St Pietropaolo (1986). An additional cultivar of Nepenthes is listed by Robinson (1989). Carpinus Cultivars of Ostrya, the hop hornbeams, and Caipinus, the hornbeams, are discussed by Rushforth (1985), Schneider (1965a), and Wright (1986). Cultivars of Carpinus and Ostrya are also discussed by Bean (1970-1988) and Kriissmann (1984-1986). Castanea The cultivars of the potentially blight-resistant chestnuts are discussed by Jaynes St Graves (1963) and Nienstaedt St Graves (1955). Ceanothus Van Rensselaer St McMinn (1942) provide the most comprehensive listing of the wild- lilacs and buckrushes. Additional cultivars are listed by Bean (1970-1988), Hogan (1988), Checklist of Cultivars 1 1 Huttleston (1986), Keeley & Keeley (1994), Kriissmann (1984-1986), Schmidt (1962), and Smith (1979). Ceratopetalum See Australian St South African plants. Cercis The cultivars of the redhuds are discussed by Raulston (1990). Chaenomeles The cultivars of the Japanese quinces are listed by Bean (1970-1988), Grootendorst (1968a), Kriissmann (1984-1986), and Weber (1963). Chamelaucium See Australian St South African plants. Chrysanthemum See Argyranthemum for the marguerite and Dendianthema for the florist's chrysanthemum. Cistus The cultivars of the rock roses are discussed by Bean (1970- 1988), Warburg (1931), and Warburg St Warburg (1930). Citrus The cultivars of Citrus, some ornamental, are listed by Hodgson (1967). Clematis A general clematis checklist is Lloyd (1965, 1989); Fretwell (1989) provides good color photographs. The cultivars of C. viticella L. are listed by Rogerson (1985). The large-flowered clematis hybrids are published by Evison (1985) and Spingarn (1935), while the hybrids of section Atragene are published by Pringle (1973). Kelsey St Dayton (1942) also provide a list of Clematis but without introduction dates and background. Some cultivars are also published by Laar (1985), Markham (1935), and Trehane (1989). Codiaeum The list for the garden croton, Codiaeum variegatum (L.) Blume, of Kelsey St Dayton (1942) provides no introduction dates or background. Additional cultivars are listed by Anonymous (1959a) and Brown (1960). The latter provides good color illustra- tions but also includes a number of botanical errors. Coleus-Plectranthus While no proper checklist exists for coleus cultivars, Pedley St Pedley (1974) and Stout (1916) provide many materials for the production of such a list. Recent registrations of Plectianthus are listed by the Australian Cultivar Registration Authority (1988). Columnea See Gesneriaceae. Conifers Lewis (1986a, b) provides a guide for the naming of conifer cultivars. The Royal Horti- cultural Society has started an ambitious registry of conifers; so far Abies to Pherosphaera have been published (Lewis, 1985; Lewis St Leslie, 1987, 1989). Meanwhile, Welch St Haddow (1993) have published a world checklist of conifers. Den Ouden St Boom (1978) and Kriissmann (1985) present the cultivated conifers with introduction dates and descriptions, while Cope (1986) provides scant information on dates or origins. Welch (1991) is an updating of both den Ouden St Boom (1978) and Welch (1979). Many cultivars of conifers are also listed by Bean (1970- 1988). Munson (1973) has prepared a vegetative key to dwarf and slow-growing conifers, while Obrizok (1991) provides growth forms of dwarf conifers. The cultivars of the firs {Abies spp.) and spruces [Picea spp.) are listed by Gelderen (1975). Silver firs, Abies alba Mill., are discussed by Horsman (1984). Japanese cedar, Cryptomeria japonica (L. f.) G. Don, cultivars are treated by Kortmann (1987) and Tripp (1993). Juniper [funiperus spp.) cultivars are listed by Gelderen (1984) and Grootendorst (1968c). Pine [Pinus spp.) cultivars are listed by Gelderen (1982), while the cultivars of Japanese five needle pine, P. paiviflora Sieb. St Zucc., are listed by Valavanis (1976). The cultivars of yews, Taxus, are listed by Chadwick St Keen (1976). The cultivars of American arborvitae. Thuja occidentalis L., are listed by Grootendorst (1971b), while Wyman 12 Ainoldia 1994-1995 Winter (1961c) discusses cultivars of four arborvitae species. Hemlock [Tsuga spp.) cultivars are documented in Swartley (1984). These should be supplemented with the color photographs of Harrison (1975) and Gelderen van Hoey Smith (1986) and the black and white photographs of Welch (1979). Cordyline A list for the cultivars of the ti, Cordyline teiminalis (L.) Kunth, is Kelsey St Dayton (1942) but without introduction dates and background. Additional cultivars are listed by Anonymous (1959d). Cornus Cultivars of the dogwoods are listed by Bean (1970- 1988) , Howard (1961), Kriissmann (1984-1986), and Santamour St McArdle (1985a). Jaynes, Brand, St Arnow list the cultivars of the kousa or Japanese dogwood, C. kousa Hance. Additional registrations are recorded by Spongberg (1988, 1990). Correa See Australian St South African plants. Corylus Bibliographic references to the cultivars of the filberts are recorded by Debor (1978). Cosmos The Indian cultivars of cosmos are listed by Anonymous (1959b). Cotoneaster The cultivars of the rock sprays are treated by Bean (1970-1988), Grootendorst (1966a), Hachmann et al. (1987), and Kriissmann (1984-1986). Crataegus Wyman (1962d) lists the cultivars of the hawthorns but with few introduction dates and little background. Bean (1970-1988), Grootendorst (1967c), and Krussmann (1984-1986) also discuss the cultivars of the hawthorns. X Crinodonna See Amaryllidaceae. Crinum The cultivars of the spider lilies are listed by Hannibal (1970-71). Crocosmia The cultivars of the montbretias are listed by Kostelijk (1984). Crocus The cultivars of crocus are documented by the Royal General Bulbgrowers' Association (1991), but further information is provided by Ruksans (1981) and Trehane (1989). Crowea See Australian &. South African plants. Cryptomeria See conifers. Cyclamen Some cultivars of Cyclamen are recorded by Grey-Wilson (1988), the Royal General Bulbgrowers' Association (1991), Trehane (1989), and Wellensiek (1961), while a comprehensive list of cultivars is Wellensiek et al. (1961). Cytisus The cultivars of the brooms [Cytisus and Genista] are treated by Bean (1970-1988), Krussmann (1984-1986), and Laar (1971). Daboecia Daboecia cultivars are included in many listings of heaths and heathers (e.g., Johnson, 1956; Munson, 1981; Underhill, 1971), and separately by Bean (1970-1988), Krussmann (1984- 1986), and Laar (1977b). Dahlia The most comphrehensive checklist of dahlias is that of the Royal Horticultural Society (1969a) and later supplements (1988d, 1989c, 1992a). Unfortunately, with one exception (a cultivar from 1850), this list omits all cultivars 1789-1859 and many of the cultivars 1860- 1900. Many early twentieth-century cultivars are amply covered in Norton (1924), Olmsted et al. (1923), and Sandhack (1927). Recent cultivars are listed by the American Dahlia Society (e.g., 1989) in a paperbound booklet as a supplement to the Bulletin of the American Dahlia Society. Dalbergaria See Gesneriaceae. Checklist of Cultivars 13 Daphne The cultivars of Daphne are listed by Brickell Mathew (1976). Bean (1970-1988), Hodgkins (1961), and Kriissmann (1984-1986) also discuss the cultivars of Daphne. Delphinium The Royal Horticultural Society (1970a) is a checklist of delphinium names that updates a list previously published in 1949. International registration of delphinium cultivars is handled by the Delphinium Society (Cooper, 1984, 1986, 1987, 1989, 1990b, 1991, 1992, 1993, 1994). Edwards (1987) and Trehane (1989) are recent lists of cultivars. Bishop (1949), Cooper (1990a), Edwards (1989), Genders (1963a), Jelitto St Schacht (1990), Ogg (1961), and the Royal Horticultural Society (1926e) also list many cultivars. Kelsey St Dayton (1942) also lists del- phiniums but without introduction dates and background. Dendranthema The cultivars of D. x grandiflorum (Ramat.) Kitamura, or florist's chrysanthe- mum, are first listed by Olmsted et al. (1923) and Kelsey St Dayton (1942). These lists omit all cultivars 1789-1889. Cumming (1964) presents some history. Scott St Scott (1950) are also recommended for early cultivars and hybridizers. Additional cultivars are listed by Gosling (1964, 1973b, 1980) and the [U.S.] National Chrysanthemum Society (1991). Genders (1961), Gosling (1973a), Jelitto St Schacht (1990), and Trehane (1989) also list some cultivars. Niwa (1936) should be consulted for Japanese cultivars. Desmodium The cultivars of the tick trefoils are listed by Lemmens (1985). Deutzia The cultivars of the deutzias are discussed by Bean (1970-1988) and Kriissmann (1958b). Dianthus The Royal Horticultural Society has published the international register for pinks and carnations (1983) with supplements (1984b, 1985b, 1986b, 1988b, 1988c, 1989b, 1990a), which supersede the 1974 list. These lists are very comprehensive, but American cultivars (such as 'Aqua') are slow to be integrated. These checklists should be used in conjunction with Bailey (1990), Mansfield (1951), Sitch (1975), and Smith (1990). The history and performance of D. gratianopolitanus Vill. and D. plumahus L. are discussed in Hensen (1981). Kelsey St Dayton (1942) include American carna- tion cultivars. Jelitto St Schacht (1990) and Trehane (1989) also list many cultivars of perennial Dianthus. Diastema See Gesneriaceae. Diervilla The cultivars of the bush honeysuckles are discussed by Schneider (1930). Dracaena The Indian cultivars of the dracaenas are listed by Anonymous (1959d). Drosera See carnivorous plants. Echeveria Carruthers St Ginns (1973) list cultivars of Echeveria but provide no dates. Epacris See Australian St South African plants. Epimedium The cultivars of the epimediums are listed by Laar (1981a). Epiphyllum See Cactaceae. Episcia See Gesneriaceae. Eremophila See Australian St South African plants. Erica A guide to naming heath cultivars is McClintock (1986). Bean (1970-1988), Chappie (1951), Johnson (1956), Kriissmann (1984- 1986), Laar (1970a, 1977a), Letts (1966), Proudley St Proudley (1974), Underhill (1990), and Laar (1974) list many cultivars of 14 Arnoldia 1994-1995 Winter heaths. Munson (1981, 1984) provides a comprehensive key to species and cultivars of Erica with full botanical descriptions in the 1981 thesis. Erigeron The history and performance of cultivars of the daisy fleabanes are discussed by Clausen (1972b), Hensen (1966), Jelitto Schacht (1990), and Oudshoorn (1975). Trehane (1989) also lists many cultivars of the daisy fleabanes. Eriostemon See Australian St South African plants. Erodium The cultivars of the heron's bills are listed by the British Pelargonium and Geranium Society (1970). Erythrina The species and cultivars of Eiythrina are listed by McClintock (1982). Escallonia The cultivars of the escallonias are listed by Bean (1970-1988), Krussmann (1984- 1986), and Schneider St Laar (1970). Eucalyptus See Australian St South African plants. Eucodonia See Gesneriaceae. Eucryphia The cultivars of Eucryphia are discussed by Wright (1983a) but with no introduction dates or background. Bean (1970-1988) and Krussmann (1984-1986) also list some cultivars. Recent registrations are listed by the Australian Cultivar Registration Authority (1988). Euonymus The cultivars of Euonymus are discussed by Bean (1970-1988), llsink St Jong (1986), Krussmann (1984-1986), Laar (1979), and Lancaster (1981). An additional registration is re- corded by Huttleston (1986). Euphorbia Ecke (1976) lists cultivars of the poinsettia. Euphorbia pulcherrima Willd. ex Klotzsch. Additional registrations are recorded by Huttleston (1989). Trehane (1989) and Turner (1983) discuss the cultivars of the hardy spurges. Eagus Wyman (1962a, 1964) lists the cultivars of the beeches but with few introduction dates and little background. Bean (1970-1988), Grootendorst (1975), and Krussmann (1984-1986) also discuss the cultivars of the beeches. Spongberg (1988, 1989) records additional registrations. Ferns Maatsch (1980) lists cultivars of ferns with descriptions, background information, and English vernacular names. Jones (1987) and Mickel (1994) list many cultivars of ferns. The cultivars of Adiantum, maidenhair ferns, are listed in Goudey (1985). The cultivars of the staghorn ferns, Platycerium, are listed by Vail (1984). The cultivars of the royal ferns, Osmunda regalis L., are listed by Anderson (1971). Recent registrations of Blechnum are listed by the Australian Cultivar Registration Authority (1988). Eorsythia The cultivars of the forsythias are published by Bean (1970-1988), Hebb (1971), Krussmann (1984-1986), Werken (1988), and Wyman (1961a, 1961b). Spongberg (1988) records additional registrations. Fraxinus The cultivars of the ashes are discussed by Bean (1970-1988), Bom (1982), Grootendorst (1966b), Krussmann (1984-1986), McArdle St Santamour (1984), and Santamour St McArdle (1983c). Fuchsia Parker (1986) provides a guide for fuchsia cultivar identification. A comprehensive checklist of cultivars of fuchsias is Boullemier (1975, 1980, 1982, 1985). Bean (1970-1988) and Krussmann (1984-1986) discuss some hardy cultivars. Ewart (1982, 1987) and Saunders (1971- Checklist of Cultivars 15 1973) describe and picture many of these cultivars. These should be used in conjunction with Manthey (1990), Proudley (1975), and Thorne (1959). Gaillardia The cultivars and performance of the gaillardias are listed by the Royal Horticultural Society (1930c). Galanthus The cultivars of the snowdrops are listed by Bowles (1956), the Royal General Bulbgrowers' Association (1991), Trehane (1989), and Yeo (1975). Genista The cultivars of the brooms [Cytisus and Genista] are treated by Bean (1970-1988), Kriissmann (1984-1986), and Laar (1971). Gentiana Bartlett (1975) includes many cultivars of gentians in her book. Many cultivars are also listed by Trehane (1989). Geranium The history and performance of cultivars of the hardy geraniums are discussed by Clausen (1974b). Yeo (1985) include: information on many cultivars of the hardy geraniums in his comprehensive book. Clifton (1992), Jelitto Schacht (1990), Trehane (1989), and Walsweer (1988) list many cultivars. Gesneriaceae Cultivars of Achimenes, the orchid pansies, are listed by the American Gesneria Society (1957), Arnold (1969), and Townsend (1984). Cultivars of Aeschynanthus are listed by Dates (1990). Cultivars of Columnea and allied genera [Bucinellina, Dalbergaria, Pentadenia, and Thchantha] are listed by Arnold (1963b, 1966) and Dates (1987). Cultivars of Episcia and Alsobia, the carpet plants, are listed by the Ameri- can Gesneria Society (1957), Arnold (1963a, 1968, 1977), and Dates (1993). Cultivars of Kohleiia, the tree gloxinias, and Smithiantha are listed by the American Gesneria Society (1957), the American Gloxinia Society (1962), Batcheller (1985), and Moore (1953). Cultivars of Nematanthus are listed by Arnold (1978). The master variety lists for Saintpaulia, the African violets, are published by Boland (1983, 1984, 1985, 1986, 1987, 1988), Frank (1975), Rector (1963), and Tretter (1976) and should be supplemented with Kawakami (c. 1981), who includes English captions and a Japanese text with color photographs. Cultivars of Sinningia are listed by Arnold (1975) and Dates (1988). Cultivars of Streptocarpus, the Cape primroses, are listed by Arnold (1972, 1979) and Brown (1973). Intergeneric hybrids in the tribe Gloxinieae (which includes Achimenes, Diastema, Eucodonia, Gloxinia, Heppiella, Koellikeha, Kohleria, Monopyle, Moussonia, Niphaea, Parakohleiia, Smithiantha, and Solenophora) are listed by Dates (1986). Geum The history and performance of cultivars of Geum are discussed by Clausen (1975) and Mallett (1983). Jelitto & Schacht (1990) and Trehane (1989) also list many cultivars. Ginkgo The cultivars of ginkgo (G. biloba L.) are discussed by Bean (1970-1988), Bom (1982), Kriissmann (1984-1986), and Santamour, He, McArdle (1983). Gladiolus Pieters (1905) is the first list of cultivars of gladiolus that we have discovered. The cultivars of gladiolus are later listed by Hottes (1916), Olmsted et al. (1923), the American Gladiolus Society (1931), Birch (1940), Pridham (1932), the Royal General Bulbgrowers' Associa- tion (1991), Sandhack (1927), and Trehane (1989). Many of these cultivars are incorporated into Fisher et al. (1975). Additions are published by Fisher (c. 1983). Gleditsia Bean (1970-1988), Bom (1982), Haserodt Sydnor (1983), Krussmann (1984-1986), 16 Arnoldia 1994-1995 Winter Santamour & McArdle (1983b), and Wagenknecht (1961a) discuss the cultivars of the honey locust (G. triacanthos L.). Gloriosa Narain (1988), the Royal General Bulbgrowers' Association (1991), and Trehane (1989) list cultivars of the climbing lilies. Gloxinia See Gesneriaceae. Grevillea The grevilleas are discussed by Larkman (1985). Recent registrations are listed by the Australian Cultivar Registration Authority (1988). See also the entry for Proteaceae. Hakea See Australian & South African plants and Proteaceae. Halesia The cultivars of the silverbells are listed by Fontaine (1970b). Hamamelidaceae The cultivars of the Hamamelidaceae are discussed by Bean (1970-1988), Kriissmann (1984-1986), Sanders (1982), Weaver (1976a), and Wright (1982). Grootendorst (1965, 1980a) and Lancaster (1970) record the background and performance of witch hazel [Hamamelis spp.) cultivars. Huttleston (1989) records an additional registration of Hamamelis. Hardenbergia See Australian St South African plants. Hebe Chalk (1988) lists cultivars of Hehe and Parahebe. Bean (1970-1988) and Kriissmann (1984- 1986) also discuss the cultivars of these two genera. Hedera The most comprehensive listing of cultivars of ivies is Heieck (1980). This should be supplemented with Fearnley-Whittingstall (1992), Hatch (1982), Kriissmann (1984-1986), Lawrence St Schulze (1942), Lawrence (1956), Nannenga-Bremekamp (1970), Pierot (1974), Rose (1980), Schaepman (1975), and publications in the Ivy Journal. Hedychium The cultivars of the ginger lilies are discussed by Schilling (1982). Hedysarum The cultivars of the Hedysarum species are listed by Lemmens (1985). Helianthemum The history and performance of cultivars of the rock roses are discussed by Clausen (1968) and the Royal Horticultural Society (1926d). Jelitto St Schacht (1990) and Trehane (1989) also list cultivars. Helianthus The history and performance of cultivars of the sunflowers are discussed by Clausen (1974c). Trehane (1989) also lists cultivars. Helichrysum See Australian St South African plants. Heliconia The cultivars of Heliconia are discussed by Berry St Kress (1991). Heliopsis The history and performance of cultivars of Heliopsis are discussed by Clausen (1974a) and Hensen (1983b). Jelitto St Schacht (1990) and Trehane (1989) also list cultivars. Helleborus The cultivars of the hellebores are discussed and illustrated in black and white drawings by Ahlburg (1993) and appended to the rear of Mathew (1989b), but the most compre- hensive descriptions, with color photographs, seem to be Rice St Strangman (1993). Hemerocallis The daylilies are first listed by Stout (1934) and Norton et al. (1949), and later in publications of the American Hemerocallis Society (1957, c. 1973, c. 1984). The species and old cultivars are discussed by Kitchingham (1985). Jelitto St Schacht (1990) and Trehane (1989) also list cultivars. Additional information is provided by Munson (1989) and Webber (1988). These should be used in conjunction with Harrow St Meyer (1968), Erhardt (1992), and Stout (1986). Heppiella See Gesneriaceae. Checklist of Cultivors 1 7 Heuchera The history and performance of the coralbells are dis- cussed by Clausen (1970) and Hansen & Sieber (1970). Jelitto St Schacht (1990) and Trehane (1989) also list cultivars. Hibiscus Kriissmann (1984-1986) discusses the cultivars of Hibis- cus. The American Hibiscus Society (1984, 1987) and Chin (1986) are checklists and illustrated catalogs of cultivars of Chinese hibiscus (H. rosa-sinensis L.). Beers St Howie (1985, 1990), Harvey (1988), and Howie (1980) are checklists of mostly Australian cultivars of Chinese hibiscus. Cultivars of rose of Sharon {H. syriacus L.) are published by Bean (1970-1988), Grootendorst (1968b), Huttleston (1986, 1988, 1990, 1991), and Wyman (1958). Kelsey St Dayton (1942) provide a list of cultivars for both species but without introduction dates and background. Hippeastrum See Amaryllidaceae. Hoheria The cultivars of the lacebarks are listed by Bean (1970-1988), Kriissmann (1984-1986), and Wright (1983a). Hosta The most comprehensive discussion of the hostas is Schmid (1991). The cultivars of the hostas are also listed in the comprehensive works by Hensen (1963a, 1963b, 1983a,1985) with comments by Grenfell (1986). These should be supplemented with Aden (1990), Fisher (1979), Grenfell (1990), Jelitto &. Schacht (1990), Laar (1967), and Trehane (1989). Houseplants Cultivars of houseplants are pictured and briefly discussed by Graf (1986a, 1986b). Hyacinthus The cultivars of hyacinths are documented by the Royal General Bulbgrowers' Association (1991), but further information is provided by Darlington, Hair, &. Hurcombe (1951). Trehane (1989) also lists the cultivars of hyacinths. Hydrangea The most comprehensive discussion of the cultivars of the hydrangeas is Mallet, Mallet, van Trier (1992). Cultivars of the hydrangeas are also covered in Bean (1970-1988), Grootendorst (1973b), Kriissmann (1984-1986), and Haworth-Booth (1984). Ilsink (1988) covers the cultivars of H. paniculata Sieb., while Wilson (1923) covers the cultivars of H. macrophylla (Thunb.) Ser. Hypericum The cultivars of the St. Johnsworts are listed by Bean (1970-1988), Kriissmann (1984- 1986), and Schneider (1965b, 1966a). Hypocalymma See Australian &. South African plants. Ilex In 1953 the Holly Society of America published a preliminary checklist (Wister, 1953b). This checklist is being revised in accordance with the International Code of Nomenclature for Cultivated Plants. First in this series is Eisenbeiss &. Dudley (1973) for I. opaca Alton, the American holly. Eisenbeiss & Dudley (1983) is an Ilex cultivar registration list 1958-1983. Andrews (1983, 1984, 1986) and Gelderen (1988) discuss the cultivars of I. x altaclerensis. The varieties of I. aquifolium L. are listed in Gelderen (1988) and Paul (1863). Wyman (1960) and Dudley & Eisenbeiss (1992) are checklists for I. crenata Thunb. Dirr (1988) and Eggerss & Hasselkus (1992) cover the cultivars of the deciduous hollies. Bean (1970-1988), Gelderen (1971), and Kriissmann (1984-1986) also list the cultivars of the hollies. These should be used in conjunction with Hansell, Dudley, & Eisenbeiss (1970). New cultivars of hollies are pub- lished in the Holly Society fournal. Impatiens The cultivars of the New Guinea impatiens are discussed by Agnew & Lang (1992), Eichin &. Deiser (1988), and Winters (1973). Indigofera The cultivars of the indigos are listed by Lemmens (1985). 18 Ainoldia 1994-1995 Winter Iris Jelitto Schacht (1990) and Trehane (1989) list many cultivars of the hardy iris but with scant information. In contrast, the listings of cultivars of bearded irises published by Peckham (1929, 1940), Douglas (1949), Knowlton (1959), Nelson (1971), and Nelson Keppel (1981, 1991, 1992a, 1992b, 1993) are rich with information. The Royal Horticultural Society (1928, 1930b) and Sand (1925) provide additional descriptions of many pre-1930 bearded irises. While the American Iris Society has published yearly checklists since the 1979 checklist, the 1989 checklist is still in press. Cultivars of the reblooming iris are listed by Brookins (1991a). Cultivars of the dwarf irises are listed by the Dwarf Iris Society (1975, 1988) and Wright (1927). Cultivars of Japanese iris [1. kaempferi Sieb. ex Lem.) are published by Brookins (1992) and the Society for Japanese Irises (1988), supplemented by McEwen (1990). Cultivars of the Siberian irises (7. sanguinea Hornem. and I. sibirica L.) are listed by Brookins (1991b) and Warburton (1986). Cultivars of the arils are listed by the Aril Society (1976, 1978, 1980, 1982). The Louisiana irises are listed by Fritchie (1982), and some color photographs, dates, and background are given by Caillet St Metzweiller (1988). Cultivars of the medians are listed by the Median Iris Society (1984, 1992). Cultivars of the spurias are listed by Foreman (1985). Cultivars of the bulbous irises are discussed by Hoog (1980) and the Royal General Bulbgrowers' Association (1991). Ixora Anonymous (1958c) is a checklist of the cultivars of the ixoras. Jasminum The cultivars of the jasmines are discussed by Bean (1970-1988), Green (1965), and Krussmann (1984-1986). An additional cultivar is listed by Huttleston (1986). Juniperus See conifers. Kalmia The cultivars of the mountain laurels are published in Jaynes (1975, 1983, 1988) and Krussmann (1984-1986); additional cultivars are published in HortScience (Jaynes, 1989). Kennedia See Australian South African plants. Kniphofia The cultivars of the torch lilies are discussed by Jelitto St Schacht (1990), Taylor (1985a, b), and Trehane (1989). Koellikeria See Gesneriaceae. Kohleria See Gesneriaceae. Kunzia See Australian St South African plants. Lagerstroemia The cultivars of crape myrtles are listed by Egolf St Andrick (1978) and Krussmann (1984-1986). Lantana The cultivars of the lantanas are listed by Anonymous (1958d), Howard (1969), and Krussmann (1984-1986). An additional cultivar is recorded by Spongberg (1988). Lathyrus Kelsey St Dayton (1942), Royal Horticultural Society (1926b), and Unwin (1926) are checklists of sweet peas, Lathyrus odoiatus L. Cultivars of the hardy perennial species are listed by Trehane (1989). Lavandula The cultivars of lavender (L. angustifolia Mill.) and lavandin (L. x intermedia Emeric ex Loisel.) are discussed by Hensen (1974), Krussmann (1984-1986), and Tucker St Hensen (1985). Lechenaultia See Australian St South African plants. Leptospermum Krussmann (1984-1986) and Metcalf (1963) are checklists of Leptospermum cultivars (mostly L. scoparium J. R. Forst St G. Forst). Recent registrations are listed by the Australian Cultivar Registration Authority (1988). Checklist of Cultivars 19 Lespedeza The cultivars of the bush clovers are listed by Lemmens (1985). An additional cultivar is listed by Huttleston (1991). Leucadendron See Proteaceae. Leucospermum See Proteaceae. Leucothoe The cultivars of L. fontanesiana (Steud.) Sleum., the drooping leucothoe, are discussed by Bean (1970-1988), Kriissmann (1984-1986), and Green (1963). Lewisia The cultivars of the lewisias are discussed by Mathew (1989a). Ligularia The cultivars of Ligularia are discussed by Dress (1962). Lilium Checklists of lilies are published by Leslie (1982) with supplements (Royal Horticultural Society, 1982, 1984a, 1985a, 1986a, 1987a, 1988a, 1989a, 1990b, 1991a, 1992b, 1993a, 1994). The North American Lily Society also has its checklists of lily hybrids (Fisher, 1978; Collings, 1986) but gives scant information on cultivars pre-1940. Additional listings are carried by Trehane (1989). Liquidambar The cultivars of the the sweet gums (L. formosana Hance and L. styraciflua L.) are discussed by Bom (1982), Kriissmann (1984-1986), and Santamour & McArdle (1984). Liriodendron The cultivars of the tulip tree (L. tulipifera L.) are discussed by Bean (1970-1988), Kriissmann (1984-1986), and Santamour & McArdle (1984). Liriope See Ophiopogon-Liriope. Lobelia The tetraploid cultivars of the Lobelia siphilitica- L. cardinalis complex are listed by Bowden (1983). Lonicera The cultivars of the honeysuckles are discussed by Bean (1970-1988), Kriissmann (1984-1986), Laar (1988), Schneider (1971), Wright (1983b), and Yeo (1964). Lophostemon See Australian St South African plants. Lupinus The cultivars and performance of the lupines are discussed by the Royal Horticultural Society (1931a). Lythrum The cultivars of Lythrum are discussed by Harp (1975). Magnolia Tresender (1978) lists many cultivars of m.agnolias, and while dates and hybridizers are generally absent, the descriptions are good. Gardiner (1989) thoroughly discusses magnolia hybrids with photographs. Additional registrations are listed in Bean (1970-1988), Kriissmann (1984-1986), and Vrugtman (1972). Fogg St McDaniel (1975) is a comprehensive list of magnolia cultivars. New cultivars of magnolias are published in Magnolia Journal. Mahonia The cultivars of the grape hollies (and x Mahoberberis] are listed by Bean (1970-1988), Brickell (1979), Kriissmann (1984-1986), and Laar (1975). Malus Bom (1982), den Boer (1959), Grootendorst (1964a), Lombarts (1984), Preston (1944), Van Eseltine (1933, 1934), and Wyman (1943, 1955) include descriptions and introductions of crabapples. (The 1943 edition of Wyman has some information dropped from the 1955 edition, including discarded cultivars and citations to a bibliography.) Jefferson (1970) clarifies the misnaming of crabapple cultivars and provides an extensive bibliography. Bean (1970-1988) and Kriissmann (1984-1986) also list the cultivars of the ornamental crabapples. Lately, crabapple registrations have been carried by the Arnold Arboretum and published in HortScience (Spongberg, 1988, 1989). Melaleuca See Australian St South African plants. 20 Ainoldia 1994-1995 Winter Melia The cultivars of the Persian lilac or Chinaberry {Melia azedarach L.) are listed by Mabberly (1984). Monarda The beebalms are discussed by Oudolf (1993). Monopyle See Gesneriaceae. Moussonia See Gesneriaceae. Myoporum See Australian South African plants. Nandina The landscape values of cultivars of heavenly bamboo, N. domestica Thunb., are discussed by Raulston (1984). Narcissus For many years the Royal Horticultural Society printed classified lists of daffodils (1908d, 1910, 1931b, 1938, 1948, 1955, 1958, 1961, 1965, 1969c, 1975), but many of these were not cumulative. The most comprehensive list of cultivars of daffodils is by the Royal Horticul- tural Society (Kington, 1989a), which updates the 1969 classified list and the classified list and international register of 1975 with supplements 1-14; supplements 15-18 are printed separately (Kington, 1989b, 1990, 1991, 1992). A checklist of daffodils has been provided as a continually updated computer printout by Throckmorton (n.d.), but very old cultivars are listed without a date. The history of cultivar registration of daffodils by the Royal Horticultural Society is documented by Donald (1986). Trehane (1989) also lists culti- vars of daffodils. Abridged lists of exhibition daffodils are published by the American Daffodil Society (1977, 1985, 1989). These should be used in conjunction with Bourne (1903), Bowles (1934), Lee (1966), Tompsett (1982), and the "Narcissus editions" of Herbertia (vol. 13, 1946) and Plant Life/Herbertia (vol. 9, no. 1, 1953). Nematanthus See Gesneriaceae. Nepenthes See carnivorous plants. Nerine See Amaryllidaceae. Nerium The cultivars of the oleanders are discussed by Anony- mous (1958a) and Pagen (1987). Nigella The cultivars of Nigella are listed by Sorvig (1983). Niphaea See Gesneriaceae. Nymphaeaceae The most comprehensive list of waterlily culti- vars is Swindells (1989b). The cultivars of waterlilies are also treated in Anonymous (I960); Conard (1905); Henkel, Rehnelt, & Dittmann (1907); Kelsey &. Dayton (1942); Swindells (1983); and Trehane (1989). Ophiopogon-Liriope The cultivars of Ophiopogon and Liriope are discussed by Hume (1961). Orchidaceae A guide to orchid hybrid (grex) registration is published by Hunt (1986). While lists have been previously published by Sanders, Sanders (1946) is the last cumulative checklist of orchid hybrids,- a list of intergeneric taxa is listed in Table II. Later, noncumulative supple- ments have been published (Sanders & Wreford, 1961; Royal Horticultural Society, 1972, 1980, 1981, 1985c, 1986c). Japan Orchid Growers Association (n.d.) has excellent color photographs of cultivars derived from Cattleya. Only Poliakoff (1987) lists Vanda cultivars with the percentage of genetic background of each ancestral species. Gilmour, Greatwood, Hunt (1976) give the names of intergeneric hybrids. Checklist of Cultivars 21 Origanum The cultivars of Origanum, the marjorams, are discussed hy Tucker Sk Rollins (1989). Trehane (1989) lists some additional cultivars. Osmunda See ferns. Ostrya See Carpinus. Paeonia The cultivars of the peonies are first listed hy Coit (1907), later hy Beal (1920) and Kelsey St Dayton (1942), and most recently hy Jelitto St Schacht (1990) and Trehane (1989). The most comprehensive listing is hy Kessenich (1976). These checklists should he supplemented with Wister (1962) for fuller descriptions and a comprehensive bibliography. Haworth-Booth (1963) and Kriissmann (1984-1986) also supply further information on the tree peonies. American peony hybrids are listed by Kessenich (1990). Later introductions have been published in the American Peony Society Bulletin. Pandorea See Australian St South African plants. Papaver The primary reference on poppy cultivars is Grey- Wilson (1993). The cultivars of the oriental (P. orientale L.), Iceland (P. nudicaule L.), and other poppies are also listed by Kelsey St Dayton (1942). Parakohleria See Gesneriaceae. Parthenocissus The cultivars of Boston ivy, P. tricuspidata (Sieb. St Zucc.) Planch, are listed by Laar (1981b, 1992). Passiflora The cultivars of Passiflora, the passion flowers, are thoroughly discussed by Vanderplank (1991). Pelargonium The most readily available guide to geranium cultivars is Krauss (1955). Bagust (1988) lists the cultivars of the dwarf geraniums. Moore (1955a, 1955b) provides background information on many species and some cultivars. The Australian Geranium Society (1978, 1985) has published the first two sections of a comprehensive Pelargonium checklist. Clifford (1970) is also useful. Penstemon Lindgren (1993) has provided a guide to registration of Penstemon cultivars. The most comprehensive guide to the genus is Lindgren St Davenport (1992). The American Penstemon Society (McWilliam, 1973, 1977) also lists registered cultivars. Pentadenia See Gesneriaceae. Perennials, herbaceous Grunert (1982), Jelitto St Schacht (1990), Kriissmann, Siebler, St Tangermann (1970), Phillips St Rix (1991), Thomas (1990), and Wehrhahn (1931) rank high among the available reference works on hardy herbaceous plants because of the wealth of information. The perennials registered by the International Registration Authority for Hardy Perennial Plants are listed by Sieber (1990a, 1990b). The cultivars of perennials, based primarily upon British catalogs, are listed by Philip (1992); perennial cultivars based upon northern European sources are listed by Laar St Fortgens (1990). Cultivars of perennials based upon American catalogs are listed by Isaacson (1989). Trehane (1989), emphasizing the cultivars available in the United Kingdom and Northern Europe, provides many dates and names of introducers. Though these latter three publications are excellent, they reinforce some incorrect synonyms by uncritically accepting catalog listings. Pernettya The cultivars of Pernettya are listed by Laar (1969) and Vogel (1969). Petunia Petunia cultivars are listed by Maatsch St Nolting (1968, 1971b) and Nolting St Zimmer (1975b, 1980b, 1984, 1987); the earliest cultivar in these is dated 1947. 22 Ainoldia 1994-1995 Wintei Philadelpbus The mock orange cultivars are listed by Bean (1970-1988), Dolatowski (1986), Hu (1954—1956), Janaki Ammal (1951), Kapranova & Lukina (1972), Kriissmann (1958c, 1984—1986), Sampson (1965), Schneider (1934), Wright (1980), and Wyman (1965). Recent mock orange cultivars are published by Huttleston (1988). Phlox Probably the most comprehensive list of phlox culivars is Trehane (1989), but very few dates are provided, lelitto St Schacht (1990), Kelsey St Dayton (1942), Kharchenko (1975), and Symons-Jeune (1953) also list phlox cultivars. Pbormium The cultivars of New Zealand flax are discussed by Cheek (1979) but more thoroughly by Heenan (1991). New cultivars are listed by Hornback (1994). Pbygelius Cultivars of Phygelius are discussed by Coombes (1988). Trehane (1989) also lists cultivars. Picea See conifers. Pieris The cultivars of the Japanese andromedas are listed by Bean (1970-1988), Bond (1982), Gelderen (1979), Ingram (1963), Kriissmann (1984—1986), and Wagenknecht (1961b). Spongberg (1988, 1990) records additional registrations. Pimelea See Australian St South African plants. Pinus See conifers. Plagianthus The cultivars of Plagianthus are listed by Wright (1983a). Plant patents The U.S. plant patents and their common names have been assembled by the American Association of Nursery- men (1957, 1958, 1959, 1960, 1961, 1962, 1963, 1967, 1969, 1974, 1981) for plant patents 1-4359. These have been pub- lished in one directory (American Association of Nurserymen, 1990) with patents 1-7088. Patents 1-477 are also listed in Kelsey St Dayton (1942). A review of the U.K. system of Plant Breeders' Rights (PBR) is Goodwin (1986). The patent- ing of plants under the European Patent Convention (EPC) and The International Union of the Protection of New Varieties of Plants (UPOV) has been reviewed by Byrne (1986), Mast (1986), and Schneider (1986b). Platanus The cultivars of the plane trees are discussed by Santamour St McArdle (1986). Platycerium See ferns. Plectrantbus See Coleus-Plectianthus. Plumeria The checklist of the Plumeria Society of America (1988) should be supplemented with the color photographs of Chinn St Criley (1982), Eggenberger St Eggenberger (1988), and Thornton St Thornton (1985). Another checklist of cultivars is Anonymous (1958b). Poaceae, Cyperaceae, and Juncaceae The best listings of the ornamental grasses, sedges, and rushes are Darke (1990), Hensen St Groendijk-Wilders (1986b), and Trehane (1989). These should be supplemented with Jelitto St Schacht (1990), Loewer (1988), Meyer (1975), Grounds (1979), Ottesen (1989), and Reinhardt et al. (1989). Lawson (1968) lists some cultivars of bam- boos. Populus Checklists of poplar cultivars are Broekhuizen (1977), International Poplar Commission (1971, 1990), Koster (1972), and Roller, Thibault, St Hidahl (1972). Bean (1970-1988) and Kriissmann (1984—1986) provide additional information. Potentilla Hachmann et al. (1986a), Jelitto St Schacht (1990), Schmalscheidt (1984), and Trehane (1989) list the cultivars of Potentilla. The cultivars of the shrubby potentillas are discussed by Checklist of Cultivars 23 Bachtell & Hasselkus (1982), Bean (1970-1988), Brearley (1987), Kriissmann (1984-1986), and Rhodes (1954). The cultivars of P. fruticosa L. are listed by Bowden (1957), Laar (1982), Schneider (1967), and Wyman (1968). An additional registration is discussed by Huttleston (1990). Primula The best listings of cultivars of Piimula is Trehane (1989). Blasdale (1948), Genders (1962, 1963b), Haysom (1957), Hecker (1971), Hyatt (1989), Jelitto &. Schacht (1990), Lyall (1959), Puttock (1957), Swindells (1989a), and Wemyss-Cooke (n.d.) also list many cultivars. Prostanthera The few cultivars of the mint shrubs are briefly mentioned by Althofer (1978). Protea See Proteaceae. Proteaceae Matthews (1983, 1993) and Vogts (1982) provide descriptions and excellent colored illustrations of cultivars of genera of the Proteaceae: Banksia, Grevillea, Hakea, Leucadendron, Leucospeimum, Protea, Serrmia, and Telopea. A guide to cultivar registration for Proteaceae is presented by Brits (1988a, c), while a "sample list" of Proteaceae cultivars is presented by Brits (1988b). Prunus Chadbund (1972) is recommended for cultivars of many flowering cherries. The Oriental flowering cherries are listed by Russell (1934), while the purpleleaf plums are discussed by Jacobson (1992). Only the Sato-zakura group of the Japanese flowering cherries has been pub- lished as a separate checklist (Jefferson &. Wain, 1984). The bibliography of this checklist, however, gives invaluable references on other ornamental Prunus. These should be supple- mented with Bom (1982), Grootendorst (1964b), Ingram (1948), Laar (1970b), Miyoshi (1916), Ohwi St Ohta (1973), and Wilson (1916). Other ornamental Prunus are listed by Bean (1970- 1988), Huttleston (1986, 1990), and Kriissmann (1984-1986). Pterostyrax The cultivars of the epaulette trees are listed by Fontaine (1970b). Pulmonaria Gultivars of the lungworts are reviewed by Mathew (1982), Jelitto &. Schacht (1990), and Trehane (1989) but generally without introduction dates or names of originators. Pultenaea See Australian &. South African plants. Pyracantha Cultivars of the fire thorns are listed by Bean (1970-1988), Laar (1966), Hachmann et al. (1986b), Kriissmann (1984-1986), Schmalscheidt (1984), and de Vos (1958). Pyrus Bean (1970-1988), Bom (1982), and Kriissmann (1984-1986) list ornamental cultivars of pears. The cultivars of the Gallery pear [P. calleryana Decne.) are discussed by Santamour & McArdle (1983a). Quercus The cultivars of the oaks are listed by Wyman (1962f) but with few introduction dates and little background. Bean (1970-1988), Bom (1982), Grootendorst (1980b), Kriissmann (1984-1986), and McArdle & Santamour (1985, 1987a, 1987b) thoroughly discuss the cultivars of oaks. Rhododendron Brickell (1980) provides guidelines for naming Rhododendron cultivars. The cultivars of rhododendrons and azaleas are first documented in Fletcher (1958), and this is updated by Royal Horticultural Society (1964, 1969b, 1988e, 1989d, 1989e, 1990c, 1991b, 1992c, 1993b); the registrations from 1962 to 1987 were originally published in The Rhodo- dendron and Camellia Yearbook and Rhododendron with Magnolias and Camellias. Kraxberger (1980) lists American Rhododendron hybrids, many of which were originally published in Rhododendrons and Rhododendron Notebook; more recently the American 24 Arnoldia 1994-1995 Winter hybrids have been listed in the Journal of the American Rhododendron Society. German Rhododendron hybrids are discussed by Schmalscheidt (1980). These checklists should be used in conjunction with Bean (1970-1988), Bowers (1960), Bulgin (1986), Cox (1985), Cox fit Cox (1988), Galle (1985), Gelderen fit Hoey Smith (1992), Greer (1982), Grootendorst (1954, 1967b, 1969b, 1969c, 1979a), Ihei (1984), Kriissmann (1984-1986), Leach (1961), Lee et al. (1965), Livingston fit West (1978), Morrison (1953), Phillips fit Barber (1967, 1979), Salley fit Greer (1986, 1992), and Schneider (1965c, 1966b). Robinia The cultivars of the locusts are listed by Bean (1970-1988), Gibbs (1929), Grootendorst (1971a), and Kriissmann (1984-1986). Rosa A proposed guide to rose name registration is Gioia (1986). The most comprehensive recent checklist of cultivars of roses is JAodern Roses 10 (Cairns, 1993), but Modern Roses 9 (Haring, 1986), Modern Roses 8 (Meikle, 1980) and Modern Roses 6 (Allan, 1965) are also important for some rose cultivars. Stock (1984) lists the older and foreign checklists (especially important for heritage roses), such as Boitard (1836), Desportes (1828), Gravereaux (1902), Mansfield (1943), Nietner (1880), Park (1956), Simon fit Cochet (1906), and Singer (1885). lager (1960) is a reprint of a privately distributed list of 1936. The Royal National Rose Society also publishes selected checklists, most recently in 1976. These should be used in conjunction with Austin (1988), Beales (1985, 1988), Bean (1970-1988), Dickerson (19932), Fagan (1988), Gault fit Singe (1971), Griffiths (1984, 1987), Harkness (1991), Kriissmann (1981), Moody (1992), and Phillips fit Rix (1988). The Combined Rose List (Dobson, 1987, 1988, 1989, 1990, 1991; Dobson fit Schneider, 1992) provides continued updating of available roses around the world with cultivar information. Rosmarinus The origins and essential oils of cultivars of rosemary are listed by Tucker St Maciarello (1986). Saintpaulia See Gesneriaceae. Salix Newsholme (1992) provides the most comprehensive descriptions of cultivars of Salix, the willows. The cultivars of the weeping willow (S. babylonica L.) are discussed by Santamour St McArdle (1988). Broekhuizen St Schneider (1969) discusses the cultivars of the white willow [S. alba L.). Anonymous (n.d.). Bean (1970-1988), and Kriissmann (1984-1986) also discuss culti- vars of willows. Sambucus The cultivars of European red elderberry, S. racemosa L., are described in German and Latin by Wolf (1923). Bean (1970-1988) and Kriissmann (1984-1986) also discuss cultivars of the elderberries. Sansevieria The cultivars of the snakeplants are listed by Morgenstern (1979), Stover (1983), and Swinbourne (1979) but without introduction dates and background. Chahinian (1986) thor- oughly treats the cultivars of S. trifasciata. Sarracenia See carnivorous plants. Saxifraga The saxifrages are listed by Kohlein (1984) but without introduction dates or back- ground. Jelitto fist Schacht (1990), Trehane (1989), and Webb fij. Gornall (1989) are comprehen- sive lists of species and cultivars. Checklist of Cultivars 25 Scabiosa The annual derivatives of S. atropurpurea L. are listed by the Royal Horticultural Society (1926c). Perennial cultivars are listed by Jelitto & Schacht (1990). Scaevola See Australian South African plants. Scbizostylis The cultivars of the Kaffir lily are listed by Straley (1984). Schlumbergera See Cactaceae. Sedum Praeger (1921) and Trehane (1989) list the cultivars of Sedum. The history and perfor- mance of cultivars of Sedum are discussed by Clausen (1978). Hensen Groendijk-Wilders (1986a) discuss the sedums cultivated in Europe. Some cultivars of sedums are listed by Evans (1983) and Jelitto & Schacht (1990) but without introduction dates or background. Sempervivum The cultivars of Sempervivum (and Jovibaia] are listed by Mitchell (c. 1973) with some color photographs and good descriptions but without dates or background. Subsequent registrations for Sempervivum (and Jovibara and Rosularia] were published by Mitchell (1982, 1983, 1985). Trehane (1989) also lists the cultivars of the houseleeks. Serruria See Proteaceae. Sinningia See Gesneriaceae. Skimmia The cultivars of Skimmia are discussed by Bean (1970-1988), Brown (1980), Laar (1984), and Krtissmann (1984-1986). Smithiantha See Gesneriaceae. Solenophora See Gesneriaceae. Sophora The cultivars of the Japanese pagoda tree, S. japonica L., are listed by Bean (1970-1988), Krussmann (1984-1986), and Schalk (1985). Sorbus The cultivars of the mountain ashes are discussed by Anonymous (1965), Bean (1970-1988), Krussmann (1984-1986), Miissell (1971), Wright (1981), and Wyman (1969b). Hensen (1970) discusses the history and performance of cultivars of the S. latifolia (Lam.) Pers. complex. Huttleston (1990) records an additional registration. Spathiphyllum The cultivars of the spathiphyllums are briefly listed by Ghase et al. (1984). Spiraea The cultivars of the spireas are listed by Bean (1970-1988), Grootendorst (1977), and Krussmann (1984-1986). Spyridium See Australian South African plants. Streptocarpus See Gesneriaceae. Styrax The cultivars of the snowbells are listed by Eontaine (1970b) and reviewed by Raulston (1992). Syringa The cultivars of lilacs are thoroughly discussed in Fiala (1988). This should be used in conjunction with Bean (1970-1988), Belorusets (1990), Bilov, Shtanko, & Mikhailov (1974), Gromov (1963), Harding (1933), Kalva (1980, 1988), Kelsey & Dayton (1942), Krussmann (1984- 1986), Luneva, Mikhailov, Sudakova (1989), McKelvey (1928), Meyer (1952), Rogers (1976), Rubtsov, Zhogoleva, & Lyapunova (1961), Stares (1928), Vrugtman (1990c, 1991), and Wister (1927, 1942, 1943, 1953a). The latest inventory of Russian cultivars has been translated into English by the International Lilac Society (Rubtsov et al., 1982). Recently the registrations have been published in HortScience (Vrugtman, 1988, 1989a, 1989b, 1990a, 1994b), while Vrugtman (1988) and Wister (1963) summarize previous registrations of lilacs. Tagetes The African, French, and signet marigold cultivars are assembled in checklists by Maatsch St Nolting (1970) and Nolting St Zimmer (1975c, 1981, 1987). 26 Ainoldia 1994-1995 Winter Taxus See conifers. Telopea See Australian &. South African plants and Proteaceae. Tetratheca See Australian South African plants. Thuja See conifers. Thymus Flannery (1982) records the cultivars of thyme in her thorough Ph.D. thesis. Tilia Bean (1970-1988), Grootendorst (1970), Kriissmann (1984-1986), and Santamour & McArdle (1985b) discuss the cultivars of the lindens. The cultivars of the lindens are also listed by Muir (1984, 1988) and Wyman (1962e) but with few introduction dates and little background. Huttleston (1989) records additional registrations. Trees, shrubs, and woody vines (broad-leaved) The best general references on the introduction dates and descriptions of many broad-leaved trees, shrubs, and vines have been Bean (1970- 1988) and Kriissmann (1984-1986). Rehder (1940, 1949) also lists many forma epithets,- because these are published before the first International Code of Nomenclature for Cultivated Plants in 1952, the forma epithets are now considered cultivar names. Other woody species are listed by Buckley (1980), Commissie voor de samenstelling van de Rassenlijst voor Bosbouwgewassen (1990), Darthuizer Boomkwekeriien B. V. (1987), Dirr (1990), Hillier (1982, 1991), Laar (1989), and Wyman (1963a, 1963b, 1966, 1967, 1969a). The mimeographed Swarthmore Plant Notes (Wister, 1954) are a treasure trove of information on cultivars of woody plants but, unfortu- nately, are not widely distributed. Registrations of recent woody genera have been published in HoitScience (Huttleston, 1986, 1988, 1989, 1990; Spongberg, 1988, 1989, 1990), while Huttleston (1986) summarizes previous registrations. Cultivars of street trees are summarized by Gerhold et al. (1989) and Wandell (1989). Some trees and shrubs are also discussed in Hogan (1988) and the journal Dendroflora (see the cumulative indices in numbers 20 and 25). Trichantha See Gesneriaceae. Trollius The cultivars of the globe flowers are listed by Clausen (1973b) and Hensen (1959). Jelitto &. Schacht (1990) and Trehane (1989) also list cultivars. Tropaeolum A list of cultivars of the common nasturtium is Kelsey Dayton (1942) but without dates of introduction. Tsuga See conifers. Tulipa The cultivars of tulips are first listed by the Royal Horticultural Society (1908c) with significant revisions in 1917, 1929, 1930a, and 1939. Later, in 1948 and 1952, the Royal Horticultural Society published revisions in conjunction with the General Dutch Bulbgrowers Society. Later the Royal General Bulbgrowers' Society (1958, 1960, 1965, 1969) and the Royal General Bulbgrowers' Association (1971, 1976, 1981) published their own lists. The 1958-1965 editions are comprehensive, but the 1969-1981 editions only provided brief descriptions and dates for many tulips, and "historical cultivars" are appended at the rear of the list with no dates or descriptions. Kelsey & Dayton (1924), Kudryavtseva (1987), and Trehane (1989) are also recommended. Ulmus The cultivars of the elms are listed by Bean (1970-1988), Fontaine (1968), Green (1964), Kriissmann (1984-1986), and Touw (1963). Spongberg (1988, 1991) records additional registrations. Variegated plants The only work on cultivars of variegated plants is Yokoi Checklist of Cultivars 11 &. Hirose (1978). While the text is in Japanese, plant names are in English. Veronica The history and performance of cultivars of Veronica are discussed by Clausen (1971). Jelitto St Schacht (1990) and Trehane (1989) also list the cultivars of Veronica. Viburnum The cultivars of the viburnums are listed by Bean (1970-1988), Egolf (1968), and Kriissmann (1984-1986). Grootendorst (1979b) discusses the cultivars of Viburnum plicatum. Vinca Barnes (1984) and Hensen (1980) discuss the history and performance of the cultivars of Vinca. Jelitto & Schacht (1990) and Trehane (1989) also list cultivars. Viola Jelitto St Schacht (1990) and Trehane (1989) list the cultivars of Viola. The history and performance of the cultivars of Viola cornuta L., the viola, are discussed by Clausen (1969) and the Royal Horticultural Society (1912, 1913a). The cultivars of violets are treated comprehen- sively by Coombs (1981). Cultivars of pansies, violas, and Violettas are listed by Fuller (1990) without dates or introducers. Weigela The cultivars of the weigelas are listed by Grootendorst (1968c), Howard (1965), and Schneider (1930). Bean (1970-1988) and Kriissmann (1958a, 1984-1986) also discuss cultivars. Spongberg (1988) records an additional registration. Wisteria Bowden (1976) and Browse (1984) review the available cultivars of the wisterias but without introduction dates or background. Sprenger (1911) lists the cultivars of W. sinensis (Sims) Sweet. Bean (1970-1988), Grootendorst (1968d), and Kriissmann (1984-1986) also discuss cultivars. Huttleston (1988) records an additional registration. Zelkova The cultivars of the zelkovas are listed by Bean (1970-1988), Dirr (1990), Fontaine (1970c), and Kriissmann (1984-1986). Zephyranthes The cultivars of the rain lilies are listed by Anonymous (1958e). Zinnia The modern cultivars of Zinnia are listed, with some history, by Sharma & Metcalf (1968). Acknowledgments We would like to thank the International Registration Authorities and the librarians at the Arnold Arboretum, Delaware State University, Longwood Gardens, Mann Library, National Arboretum, National Agricultural Library, Pennsylvania Horticultural Society, Royal Botanical Gardens, Smithsonian (Botany), and University of Delaware. The senior author also thanks the Cooperative State Research Service (#801-15-01C) and the State of Delaware for financial assistance. Frontispiece from the sixth edition of The Gardeners Dictionary by Philip Miller, 1752. Literature Cited Aden, R, ed. 1990. The hosta book. 2d ed. Portland, OR: Timber Press. Agnew, N. H., and H. J. Lang. 1992. Outstand- ing New Guinea impatiens. Green- house Manager 10(10): 66-70. Ahlburg, M. S. 1993. Hellebores: Christmas rose, Lenten rose. Trans. M. S. Ahlburg and J. Hewitt. London: B. T. Batsford. Ahrendt, L. W. A. 1942. An analysis of the Wisley hybrid Berberis. J. Roy. Hort. Soc. 67: 129-135. . 1949. The Berberis stenophylla hy- brids. /. Roy. Hort. Soc. 74: 36-40. . 1961. Berberis and Mahonia: A taxo- nomic revision. /. Linn. Soc., Bot. 57: 1-410. Allan, P. 1988. Naming of cultivated plants. Protea News 7: 18-22. Allen, 1. 1983. Adventures with asters. Hardy PI. Soc. Bull. 6(3): 75-79. Allen, R. C. 1965. Modern roses 6. Harrisburg, PA: J. Horace MacFarland. Althofer, G. W. 1978. Cradle of incense: The story of Australian Prostanthera. Soc. Growing Austral. PL American Association of Nurserymen. 1957. Plant patents: Common introductory names 1 through 1542. Washington, DC: Am. Assoc. Nurserymen. . 1958. 1957 Supplement to plant patents: Common introductory names 1543 through 1671. 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Plant patents with common names 3413-4359. 1974-1978. Wash- ington, DC: Am. Assoc. Nurserymen. . c. 1987. How to use, select, and register cultivar names. Washington, DC: Am. Assoc. Nurserymen. . 1990. Plant patent directory. Washing- ton, DC: Am. Assoc. Nurserymen. American Begonia Society. 1957. Buxton check list of begonias. Los Angeles: Am. Begonia Soc. . 1958. Buxton check list of begonias. Suppl. no. 1. Los Angeles: Am. Begonia Soc. . 1962. Buxton check list of begonias. 30 Arnoldia 1994-1995 Winter Suppl. no. 2. Los Angeles: Am. Begonia Soc. . 1967. Buxton check list of begonias. Suppl. no. 3. Los Angeles: Am. Begonia Soc. . 1985. Catalog of registered cultivars of the genus Begonia. Vol. 1. Registration Numbers 1-100. Encinitas, CA: Am. Begonia Soc. American Daffodil Society. 1977. Daffodils to show and grow. New Canaan, CT: Am. Daffodil Soc. . 1985. Daffodils to show and grow and abridged classified list of daffodil names. 3rd ed. Hernando, MS: Am. Daffodil Soc. . 1989. Daffodils to show and grow and abridged classified list of daffodil names. 4th ed. Hernando, MS: Am. Daffodil Soc. American Dahlia Society. 1989. 1989 Classifi- cation and handbook of dahlias. Am. Dahlia Soc. American Gesneria Society. 1957. Names and descriptions of plants currently in the trade. Achimenes. Episcia. x Gloxinera. Smithiantha. Gesneriad Reg. [publ. with Gesneriad J. 4(4)]. American Gladiolus Society. 1931. Descriptive gladiolus nomenclature. Am. Gladi- olus Soc. American Gloxinia Society. 1962. Names and descriptions of plants commercially available. Kohleiia. Smithiantha. Gesneriad Reg. [publ. with Gloxinian 12(5)]. American Hemerocallis Society. 1957. Hemerocallis check list 1893 to July 1, 1957. Am. Hemerocallis Soc. . c. 1973. Hemerocallis check list July 1, 1957 to July 1, 1973. Am. Hemerocallis Soc. . c. 1984. Hemerocallis check list July 1, 1973 to December 31, 1983. Am. Hemerocallis Soc. American Hibiscus Society. 1984. Hibiscus catalogue. Am. Hibiscus Soc. . 1987. Nomenclature of the American Hibiscus Society. Am. Hibiscus Soc. Anderson, A. J. 1971. Osmunda regalis and its forms. Gard. Chron. 169(11): 32. Andrews, J. 1984. Peppers: The domesticated capsicums. Austin: Univ. Texas Press. Andrews, S. 1983. Notes on some Ilexx altaclerensis clones. Plantsman 5: 64— 81. . 1984. More notes on clones of Ilex x altaclerensis. Plantsman 6: 157-166. . 1986. The clones of Ilex x altaclerensis. Acta Hort. 182: 377-380. Anonymous, n.d. Willow varieties for Alaska. Palmer, AL: Plant Mater. Center. . 1958a. Oleander. Bull. Lucknow Natl. Bot. Gard. 10: 1-8. . 1958b. Plumeria. Bull. Lucknow Natl. Bot. Gard. 14: 1-11. . 1958c. Ixora. Bull. Lucknow Natl. Bot. Gard. 15: 1-14. . 1958d. Lantana. Bull. Lucknow Natl. Bot. Gard. 19: 1-12. . 1958e. Cooper anthes and Zephyranthes. Bull. Lucknow Natl. Bot. Gard. 20: 1-34. . 1958f. Amaryllis. Bull. Lucknow Natl. Bot. Gard. 21: 1-27. . 1959a. Codiaeum (croton). Bull. Lucknow Natl. Bot. Gard. 31: 1-24. . 1959b. Cosmos (Cosmea). Bull. Lucknow Natl. Bot. Gard. 34: 1-16. . 1959c. Bougainvillea. Bull. Lucknow Natl. Bot. Gard. 41: 1-35. . 1959d. Cordylines & dracaenas. Bull. Lucknow Natl. Bot. Gard. 42: 1-18. . 1960. Nymphaea, Nelumbo, Luryale and Victoria. Bull. Lucknow Natl. Bot. Gard. 50: 1-20. . 1965. Sorbus. Dendroflora 2: 28-44. Aril Society. 1976. The Aril Society interna- tional official checklist. Aril Soc. . 1978. The Aril Society international official checklist. Add. no. 1. Aril Soc. . 1980. The Aril Society international official checklist. Add. no. 2. Aril Soc. . 1982. The Aril Society international official checklist. Add. no. 3. Aril Soc. Arnold, P. 1963a. Names and descriptions of Literature Cited 31 plants commercially available in the genus Episcia. Gesneriad Reg. [publ. with Gloxinian 13(1)). . 1963b. Names and descriptions of plants commercially available in the genus Columnea. Gesneriad Reg. [publ. with Gloxinian 13(6)]. . 1966. Names and descriptions of plants commercially available in the genus Columnea. Gesneriad Reg. [publ. with Gloxinian 16(3)]. . 1968. Names and descriptions of plants commercially cultivated in the genus Episcia. Gesneriad Reg. [puhl. with Gloxinian 18(1)]. . 1969. Names and descriptions of plants commercially available in the genus Achimenes and registered cultivar names. Gesneriad Reg. [publ. with Gloxinian 19(5)]. . 1972. Names and descriptions of cultivated plants in the genus Streptocarpus. Gesneriad Reg. [puhl. with Gloxinian 22(5)]. . 1975. Check list of names with de- scriptions of cultivated plants in the genus Sinningia. Gesneriad Reg. [publ. with Gloxinian 25(2)]. . 1977. Check list of names with de- scriptions of cultivated plants in the genus Episcia. Gesneriad Reg. [publ. with Gloxinian 27(2)]. . 1978. Check list of names with de- scription of cultivated plants in the genus Nematanthus. Gesneriad Reg. [publ. with Gloxinian 28(5)]. . 1979. Check list of names with de- scriptions of cultivated plants in the genus Streptocarpus. Gesneriad Reg. [puhl. with Gloxinian 29(6)]. Ashburner, K. 1986. Alnus — A survey. Plantsman 8: 170-188. . 1980. Betula — A survey. Plantsman 2: 31-53. Austin, D. 1988. The heritage of the rose. Woodbridge, England: Antique Collec- tors' Club. Australian Cultivar Registration Authority. 1988. Registered cultivars. Austral. Cultivar Registration Authority. Australian Geranium Society. 1978. A check list and register of Pelargonium cultivar names. Pt. 1, A-B. Sydney: Austral. Geranium Soc. . 1985. A check list and register of Pelargonium cultivar names. Pt. 2, C- F. Sydney: Austral. Geranium Soc. Bachtell, K. R., and E. R. Hasselkus. 1982. Selecting varieties of shrub Potentilla for the Midwest. Am. Nurseryman 155(3): 83-89. Bagust, H. 1988. Miniature and dwarf gerani- ums (Pelargoniums). Portland, OR: Timber Press. Bailey, S. 1990. Carnations. London: Blandford. Barnes, P. 1984. Trial of Vinca cultivars. Garden (London) 109: 426-429. Barret, P. W. 1959. Aster ericoides. Hardy PL Soc. Bull. 2(1): 17-18. Bartlett, M. 1975. Gentians. Poole, England: Blandford Press. Batcheller, F. N. 1985. Check list of names with descriptions of cultivated plants in the genus Kohleria. Ed. J. D. Dates. Gesneriad Reg. [publ. with Gloxinian 35(5)]. Batdorf, L. R. 1987. International registration list of cultivated Buxus L. Boxwood Bull. 16: 76-81. . 1988. Checklist of Buxus L. Boxwood Bull. 28: 43-49. Beadle, D. A. 1991. A preliminary listing of all known cultivar and grex names for the Bromeliaceae. Corpus Christi, TX: Bromeliad Soc. Beal, A. C. 1920. The peony: a flower for the farmer. Cornell Reading Course for the Farm, Lesson 154. Ithaca: N.Y. State College of Agriculture, Cornell Uni- versity. Beales, P. 1985. Classic roses. New York: Holt, Rinehart and Winston. . 1988. Twentieth-century roses. New 32 Arnoldia 1994-1995 Winter York: Harper Row. Bean, W. K. 1970-1988. Trees and shrubs hardy in the British Isles. 4 vols. + suppl. London: John Murray. Beckett, K. A. 1983. Bergenia. Garden (Lon- don) 108: 480-484. Beers, L., and J. Howie. 1985. Growing hibis- cus. Kenthurst, Australia: Kangaroo Press. . 1990. Growing hibiscus. 2d ed. Kenthurst, Australia: Kangaroo Press. Belorusets, E. Sh. 1990. Siren' (in Russian). Kiev: Uroshai. Berry, F., and W. J. Kress. 1991. Heliconia: An identification guide. Washington, DC: Smithsonian Inst. Press. Bilov, V. E., 1. 1. Shtanko, and N. L. Mikhailov. 1974. Siren' (in Russian). Moscow: Hayka. Birch, C. H. 1940. Parentages of named variet- ies. Gladiolus 1940: 33-40. Bishop, F. 1949. The delphinium: A flower monograph. London: Collins. Blasdale, W. C. 1948. The cultivated species of Primula. Berkeley: Univ. California Press. Boitard, P. 1836. Manuel complet de I'amateur de roses. Paris: Libr. Encycl. Roret. Boland, M. 1983. African violet master variety list 1976-1983. Registered varieties 1948-1983. Knoxville, TN: African Violet Soc. Am. . 1984. The 1984 master list of African violets. African Violet Mag. 37(4): 43- 55. . 1985. The 1985 master list of African violets. African Violet Mag. 38(4): Suppl. . 1986. The 1986 master list of African violets. African Violet Mag. 39(5): 31- 42. . 1987. The 1987 master list of African violets. African Violet Mag. 40(6): 27- 45. . 1988. The 1988 master list of African violets. African Violet Mag. 41(6): Suppl. Bom, P. L. M. van der. 1982. Amerikaanse selecties van straat-, laan- en parkbomen. Dendroflora 19: 44-82. Bond, J. 1982. Pieris — A survey. Plantsman 4: 65-75. Boullemier, L. B. 1975. A check list of species, hybrids and cultivars of the genus Fuchsia with 1976 Add. no. 1, 1978 Add. no. 2. Poole, England: Blandford Press. . 1980. Add. no. 3 to a check list of species, hybrids and cultivars of the genus Fuchsia. Poole, England: Blandford Press. . 1982. Add. no. 4 to a check list of species, hybrids and cultivars of the genus Fuchsia. Poole, England: Blandford Press. . 1985. The checklist of species, hybrids and cultivars of the genus Fuchsia. Poole, England: Blandford Press. Bourne, S. E. 1903. The book of the daffodil. London: John Lane. Bowden, W. M. 1957. Cytotaxonomy of Potentilla fruticosa, allied species and cultivars. J. Arnold Arbor. 38: 381-388. . 1976. A survey of Wisterias in south- ern Ontario gardens. Roy. Bot. Gard. Techn. Bull. No. 8. . 1983. Descriptions of eighteen tetrap- loid Lobelia cultivars. Simcoe, Ontario: Wray M. Bowden. Bowers, C. G. 1960. Rhododendrons and azaleas: Their development, cultiva- tion and development. New York: Macmillan. Bowles, E. A. 1934. A handbook of narcissus. London: Martin Hopkinson. . 1956. Garden varieties of Galanthus. Pp. 65-70 in F. C. Stern, Snowdrops and snowflakes. London: Roy. Hort. Soc. Brearley, C. 1987. The shrubby potentillas. Plantsman 9: 90-109. Brickell, C. D. 1979. The hybrids between Mahonia japonica and M. lomariifolia. Plantsman 1: 12-20. Tne Amola ArLoretum E R NEWS 1 9 9 4 - 1 9 9 5 A Literary Trilogy Completed Robert E. Cook, Director In the summer of 1840, William Henry Channing became close friends with the transcendentalist Margaret Fuller, disciple of Ralph Waldo Emerson and editor of the transcenden- tal journal. Dial. Channing later wrote of one visit with her: It was a radiant and refreshing morning. . . . She proposed a walk in the open air. She led the way to Bussey’s wood, her favorite retreat during the past year, where she had thought and read, or talked with intimate friends. We climbed the rocky path, resting a moment or two at every pretty point, till, reaching a moss-cushioned ledge near the summit, she seated herself. For a time she was silent, entranced in delighted communion with the exquisite hue of the sky, seen through interlacing boughs and trembling leaves, and the play of shine and shadow over the wide landscape. Thirty-two years later, Bussey’s wood became the Arnold Arboretum. It seems that Benjamin Bussey, gentle- man farmer of Jamaica Plain, opened his entire estate to the community from the time he acquired the land in the early 1800s until he bequeathed it to Harvard University. In this sense, the Arboretum has been enjoyed by the public for many more years than those since its founding in 1872; the formal establishment of the institution simply recognized what was a widely appreciated but informal practice of excursions to enjoy the beauty of the setting. • continued on page 2 • from page 1 The occasion for my discovery of this fact, and of the quote from Channing above, was the recent publication of Science in the Pleasure Ground, the third of a trilogy of books by staff members about the scientific and cultural importance of the Arnold Arboretum. Science in the Pleasure Ground is skillfully authored by Ida Hay, formerly Curatorial Associate here, and it recounts in rich detail the changes in the Arboretum landscape over time and the history of the institution as expressed in those changes. The earlier two volumes, A Reunion of Trees by Steve Spongberg and New England Natives by Sheila Connor, spun narratives about the importation of exotic woody plants from the Far East into North America and about economic and horticultural uses of the native species and for- ests by the several cultures that have occupied the land of New England. The publication of Ida’s book completes a magnificent project. begun over ten years ago and supported by several grants from the National Endowment lor the Humanities, that has provided us with a much deeper understand- ing of the humanistic dimensions of the Arboretum and the critical importance of our living collection of trees to the scientific and cul- tural developments of the past century. I congratulate all three authors for the high quality of their work, and for the heritage they have rendered accessible to us all. MHS Honors John H. Alexander III The Massachusetts Horticultural Society bestowed the prestigious Jackson Dawson Medal on Arnold Arboretum propagator John H. Alexander III in recognition of his skill and thoroughness in develop- ing and disseminating propaga- tion techniques. Jack, whose career at the Arboretum began in 1976, is well known for his work with the Arboretum’s lilac collec- tions and his extensive teaching as well as for his many contribu- tions to the propagation of woody plants. He is seen here at the 1994 Honorary Medals and Awards Cer- emony with, on his right, Walter M. Pile, Jr., Chairman of the MHS Board of Trustees, and Executive Directot John C. Peterson. The Jackson Dawson Medal itself honors an Arboretum propa- gator, master plantsman, and longtime superintendent whose forty-three-year career here began in 1873 as founder Charles S. Sargent’s first staff member. Friends of the Arboretum Gain Free Admission to More Than 1 00 Arboreta & Botanical Gardens We are pleased to announce a new benefit for Friends of the Arnold Arboretum: free admission and gift shop discounts at over one- hundred arboreta, botanical gar- dens, and conservatories across the United States and Canada. Among the many institutions participat- ing in this reciprocal admission program are the Brooklyn Botanic Garden, New York Botanical Garden, the Strybing Arboretum & Botanical Gardens, Missouri Botanical Garden, Denver Botanic Gardens, and the Royal Botanic Gardens in Hamilton, Ontario. Arboretum members also ben- efit from the reciprocity arrange- ment by receiving free admission to the Massachusetts Horticultural Society’s annual New England Spring Flower Show, taking place this year March 1 1 through 19- All current Arboretum mem- bers will receive a new membership card and a complete list of partici- pating institutions. Simply present your Arboretum membership card to take advantage of the new program. If you have questions, or would like to open or renew membership, please contact Lisa Hastings at 524—1718, ext. 145. 2 Bob Howard Hemlock Hill — The End of an Era Peter Del T redid. Assistant Director for Living Collections Hemlock Hill has always occupied a special place in the history of the Arnold Arboretum as a little piece of wilderness in the heart of the big city. E. H. Wilson summarized the pride felt by Arboretum staff members in his 1925 book, America’s Great Garden, “Within the hemlock grove reigns the still- ness of primeval forest broken only by the babbling of the waters which wash its feet . . . within the limits of no other city can such a grand and inspiring bit of natural forest be found.” Research published by Hugh Raup in 1935, however, made it clear that Hemlock Hill was far from being a “primeval” wilderness — it had been heavily lumbered during the late 1700s and early 1800s, and the hemlocks that dominated the landscape when the Arboretum was founded in 1872 had grown up after this log- ging. Regardless of its origin, however. Hemlock Hill has always had a wild feeling, very different from the rest of the Arboretum. Unfortunately, a large portion of Hemlock Hill came crashing down during the great hurricane of September 21, 1938, when over 400 trees were blown over, mainly on the southeast slope. These included some of the largest, which dated back to at least 1780. In the two or three years following the hurricane, the hill was replanted with new hemlock seedlings to help stabilize the slopes and to restore the forest, with Donald Wyman bleakly predicting that “It will take the better part of a century before the magnificent grove of Hemlock Hill will again approach its perfection of September 1938.” By the time I started working at the Arboretum in 1979, however. Hemlock Hill had once again achieved the feeling of a wild forest, with a few old specimens interspersed among a mass of much younger trees. Seedling regeneration has always been virtually nonexistent on the hill, a function of the dense shade that hemlocks cast, of their highly absorptive root systems, and of the heavy foot traffic that parades up and down the slopes. Periodic storms and hurricanes since 1938 have continued their relentless program of tree removal, culling specimens with rotten cores or weak roots. This combination of ongoing mortality and lack of seedling recruitment has been a source of concern for the staff for many years, with no obvious solution in sight. The big nor’easter that struck Boston on December The “hanging wood” of Hemlock Hill photographed in 1905 by T. E. Marr. 24, 1994, was yet another reminder that the problem of Hemlock Hill will get worse before it gets better. Two of the biggest trees left on the top of the hill were blown down. Both were there before the Arbo- retum was founded, and both were totally hollow at the base. One of the trees, approximately 80 centi- meters in diameter, had 125 rings at 15 feet above the ground, suggesting an age of at least 150 years. The other tree was over 90 centimeters in diameter and appeared to be of about the same vintage. Along with these two giants, five smaller trees, probably planted after the hurricane of 1938, also came down. From a management point of view Hemlock Hill has always been problematic. On the one hand, it receives minimal maintenance because we like to think of it as a “natural” area. On the other, it is heavily trafficked, and erosion and vandalism (mainly fires) can become very serious problems if not treated or prevented. And just to make matters worse, a new pest, the hemlock woolly adelgid, has recently been found on Arboretum property. This insect, whose arrival had been anticipated for several years, has devastated hemlock populations, both wild and cultivated, throughout the mid-Atlantic region. More recently, the insect has been spotted in hem- lock forests throughout southern new England. • continued on page 4 3 • from page 3 While the pest can be controlled by spraying dor- mant oil, it is difficult, if not impossible, to control its spread in dense stands of tall trees. Only the Chinese species, Tsuga chinensis, appears to be fully resistant to damage from the adelgid. These factors have led the Living Collections Committee to revise its management program lor Hemlock Hill. The first change has been to allow as much organic matter as possible to remain on the hill in an attempt to encourage natural seedling re- generation. This translates into a policy that calls for chipping up the branches of the tree (thereby mini- mizing the fire hazard) and leaving the trunks where they fall to act as “nurse” logs. The second step will be to plant open areas with Tsuga chinensis in an ef- fort to head off total devastation by the adelgid. This species is rarely cultivated in North America. While we have a few old specimens at the Arnold Arbo- retum,we have begun assembling specimens from various parts of its natural range. With a little luck they will be ready to plant out in three or four years. Mercer Fellow Lisa Curran has been granted a two-year Mercer Fellowship to work with the Arboretum’s Indo- nesian Biodiversity Collections project. Since receiving her under- graduate degree from Harvard University in 1984, Lisa has been investigating the ecology, use, and management of tropical forests in Kalimantan (Indonesian Borneo). She assisted the Indonesian gov- ernment with biodiversity surveys and research programs in two forest reserves that were later up- graded to national park status. She also conducted a number of field courses in tropical botany while in Kalimantan, and on several occasions served as a forestry con- sultant to the government of Indonesia. In field surveys and investigations of over seventy Kalimantan timber concessions and affiliated wood-based industries, she evaluated the ecological, economic, and social impact of government policies and timber company practices on for- est resources and local village communities. In July 1994, Lisa received her Ph.D. from the Department of Ecology and Evolutionary Biology at Princeton University with a thesis entitled “The ecology and evolution of mast-fruiting in Bornean Dipterocarpaceae: A gen- eral ectomycorrhizal theory.” It was based on her eight-year study of the reproductive biology and regeneration of the prominent family of Southeast Asian com- mercial timber trees and their insect and vertebrate seed preda- tors. Her current research interests center on the impact of forest poli- cies and practices on biodiversity in tropical canopy trees and the effects of seedling recruitment fluctuations on the maintenance of species diversity. Lichens: Fine Details of the Natural Landscape Lichens — actually symbiotic associations between fungi and algae or cynobacteria — are among the most ubiquitous forms of life across the globe. From February 2 1 to May 15, the Arboretum will present a photographic exhibit that explores the natural history of this fascinating group of organisms. “Lichens: Fine Details of the Natural Landscape” will be available for viewing in the Arboretum’s Hunnewell Building at 125 Arborway in Jamaica Plain. The Arboretum will also offer a free lecture, “Lichens, a Special Biological Interaction,” by Donald H. Pfister, Asa Gray Professor of Systematic Botany, Harvard University. The lecture will be held on Tuesday, April 4, at 7:30 pm in the Hunnewell Building. To register, please call 617/524-1718 ext.l62. 4 Karen Madsen What Is Landscape? . . ."A piece of land which is old or has nature" . . ."How the land works" . . ."What you can see through your eyes" Richard Schulhof, Assistant Director for Education and Public Affairs Over one hundred 6th-grade students at the Doherty Middle School in Andover ventured a response to the key question addressed in the new Arboretum pro- gram, Junior Parkmakers: What is landscape? Supported by grants from the National Endowment for the Arts and the National Park Foundation, the Arboretum and the Olmsted National Historic Site are working together to introduce Boston-area children to the concepts of landscape and landscape history. Development of the program began this past fall with focus groups comprised of local teachers and museum educators. Mary Chmielecki, a teacher at the Doherty School, tested the power of the word landscape with her students. She asked them to define their idea of it in one sentence and then to draw it. Their responses underscored the word’s ability to evoke a wide range of personal interpretations. Although the highly varied responses made categorization difficult, roughly 25 percent thought of it as a verb (“making the lands look better”), 30 percent interpreted it as a natural or aesthetically pleasing place (“beautiful, fresh-looking scenery”), and 40 percent as a quantity or unit of land (“land for about a mile”). While all of the participants included trees in their drawings, a few children described landscape as construction sites or areas for dumping and included bulldozers or abandoned cars in their drawings. These descriptions provide an extremely useful snapshot of the diverse perspectives that participants will bring to the program. We extend our many thanks to Ms. Chmielecki and her students for their creative and enlightening contribution. Junior Parkmakers will be field-tested later this year; it will include classroom activities and visits to the Arbore- tum designed to connect kids with Boston’s rich heritage of historic and designed landscapes. 5 Understanding Urban Trees: Getting to the Root of the Matter Kirn E. Tripp, Putnam Fellow Trees in cities have much to con- tend with. Restricted rooting areas, high winds, severe temperature fluctuations, extremes of drought and flooding, compacted or con- taminated soils with high concen- trations of salt, and repeated mechanical damage affect the tree’s ability to maintain actively growing and functional roots. Moreover, they must cope with these extreme conditions immedi- ately following one of the most stressful perturbations that man- aged woody plants are subjected to, namely, transplanting. No tree in nature is subjected to this kind of disturbance — seedling trees may be chewed on, crushed by fallen limbs, stepped on, or attacked by disease, but they are not uprooted to be replanted miles away in an alien, stressful environment. In modern horticulture, tree seed, cuttings, and young trees are brought from a range of climates around the world to nurseries where they are grown with nearly optimal fertilization and irriga- tion. In field-production nurseries, plants may lose as much as eighty to ninety percent of their root sys- tems when they are dug for ship- ping to a new site. The advent of the mechanical tree spade has made it virtually impossible to transplant large trees without los- ing most of their mass of fine roots — those roots most important for water and nutrient uptake in support of the whole organism. This means that, once replanted, trees must be able to regrow significant masses of fine roots as quickly as possible in order to sur- vive. That ability, which varies widely among species and even among cultivars and hybrids with shared parentage, becomes a dominant factor in determining survival. My research project at the Arnold Arboretum addresses this issue in two ways: Which orna- mental woody plants in the diverse living collections of the Arnold Arboretum have over time demonstrated good potential for surviving in stressful managed environments? And among these successful plants, are there simi- larities in root growth patterns 'A A successfully rooted cutting of Alnus japonica, the Japanese alder. that permit us to generalize about what leads to successful root de- velopment and long-term survival in stressful environments, and thereby better predict which trees might thrive in such sites? The first question is readily answered by straightforward evaluation of the collections with reference to the invaluable records that detail source, age, and prior management. Over the past year I have had the great pleasure of dis- covering many interesting and un- usual ornamental woody plants that show great potential for urban use. I am currently working to document optimal propagation techniques for these plants and to promote them for commercial production. I have addressed the second question by investigating how woody plants invest in root growth relative to shoot growth. My previous work and that of others has uncovered a clear coin- cidence between success in envi- ronments hostile to root growth and allocation of significantly greater proportion of overall growth to roots than to other parts of the plant. This pattern holds up even among closely related plants. For example, if we grow two closely related hollies from rooted cuttings — one that performs well in stressful root environments and one that doesn’t — we find that the successful holly consistently allo- cates much more of its growth to its root system than to its aboveground parts. This prefer- , ence for investment in root growth versus shoot growth remains consistent throughout early development from rooted cuttings, through the container- grown stage, and on through two seasons in the field. These findings help us under- stand urban tree growth and de- velopment. They may also allow us to develop relatively rapid screens for successful urban plants simply by rooting cuttings and growing seedlings of untried spe- cies and cultivars. This two-fold project is a unique opportunity for me to take advantage of the great diversity and excellent documen- tation of the living collections at the Arnold Arboretum in service to both practical and theoretical horticulture. 6 PROGRAMS(S> EV ENTS spring and summer are prime seasons for gardeners, and the Arboretum offers many short courses in horticul- ture and botany. Begin your gardening career with introductory courses, or improve your skills with advanced courses in horticultural techniques and plant study. A selection is shown below. For a complete catalogue of programs and events at the Arboretum, call (617) 524-1718, ext. 162. Please note that course fees printed in boldface are for Arboretum members. APRIL HOR 327 Starting and Running a Home Nursery John H. Alexander III, Chief Plant Propagator, Arnold Arboretum Are you growing so many plants that you some- times feel you might as well be running a nursery? Would you like to sell some of the plants you produce? In this workshop for the serious amateur, your questions will be answered. Is a greenhouse required? Where should you buy supplies, stock, liners, equipment? What are the legal aspects of starting a nursery? What about irrigation? How should you inform customers of your offerings? Can you manage without a catalog? Extensive handouts are included. Bring a lunch. Fee: $117, $134 2 Saturdays, April 1, 8/ 9:00 am-3:30 pm (Dana Greenhouse) HOR 195 Successful Tree and Shrub Planting James F. Martin, Professional Arborist and Horticultural Instructor Establishing young trees and shrubs is an important spring gardening task for the homeowner and gar- den professional. Learn planting techniques that will give a new tree or shrub the best chance of sur- vival. This course will cover decisions to be made at the time of purchase, transportation, planting hole preparation, settling the plant in, finishing touches, and maintenance. The course is appropriate for both novice and experienced gardeners as well as for horticultural professionals. Please dress for the outdoors. Fee: $40.00, $46.00 2 Saturdays, April 1, 8/ 9:30— noon (Case Estates) HOR 172 Bamboos in the Home Landscape Chris DeRosa, Owner, New England Bamboo Company Bamboos add movement, grace, and elegant form to your garden. Beautiful as they are, gardeners know that some bamboos can become invasive garden problems. Join Chris DeRosa, a recognized bamboo expert, to learn about the variety of hardy bamboos suitable for New England gardens, their culture and uses in the landscape. Fee: $12, $15 Thursday, April 6/ 7:00—8:30 pm (Case Estates) HOR 1 10 Fundamentals of Gardening Laura Eisener, Landscape Designer Whether you are a novice starting your first garden or an old hand looking for a firmer foundation, this practical course will satisfy your quest for basic gar- dening information. In four sessions this course will cover basic techniques of gardening, including site analysis and soil preparation, irrigation, drainage, watering, plant selection, and horticultural require- ments of plants. Weather permitting, there will be some hands-on work at the site, in addition to lec- tures and demonstrations. Fee: $85, $100 4 Fridays, April 7, 14, 21, 28/ 10:00 am— 12:30 pm (Case Estates) MAY Identification of Temperate Woody Plants Arnold Arboretum Staff Members Gary Roller, Stephen Spongberg, Chris Strand, and Kim Tripp. Marcia Mitchell, Course Coordinator This introductory course, taught by Arnold Arbore- tum staff members, is designed to provide a solid foundation for the identification of woody plants hardy in New England. Students may begin the two-semester curriculum in either fall or spring. HOR 101 Identification of Temperate Woody Plants (Spring) includes deciduous shrubs, small flowering trees, and the spring characteristics of larger landscape trees and conifers. HOR 102 Identification of Temperate Woody Plants (Fall ) includes the autumn aspect of these genera and species, and presents conifers, broadleaf evergreens, and other plants whose key characteris- tics are best observed in the fall and winter. Fee: $125, $150 7 Tuesdays, May 2, 9, 16, 23, 30, June 6, 13/ 10:00-noon (Dana Greenhouse) 7 Karen Madsen New Staff at the Arboretum Carol David brings five years of librarianship to her position as the new Library Assistant at the Hor- ticultural Library. Her responsi- bilities include reference services, acquisitions, and technical ser- vices. At present ninety percent of the horticultural collection is not on HOLLIS, Harvard’s online catalog. Her immediate concern will be to continue to update online access in order to accelerate research efforts. Carol is a gradu- ate student of library science at Simmons College and comes to us from the Lucien Howe Library of Ophthalmology and Otolaryn- gology at Massachusetts Eye and Ear Infirmary. Lisa M. Hastings recently joined the Arboretum as Development Officer. Her responsibilities in- clude managing the Arboretum’s membership and annual appeal ef- forts and planning and otganizing events related to the Arboretum’s participation in the University’s Capital Campaign. She joins us from Worcester Polytechnic Insti- tute in Worcester where, as Direc- tor of Young Alumni Programs, she was responsible for all aspects of fundraising and program man- agement for WPI’s young alumni constituency of seven thousand. Lisa is a longtime volunteer at the Eisher Museum of Eorestry at the Harvard Forest in Petersham and at the Worcester County Horti- cultural Society. 1 995 Winter Lecture Series: The Nature of Cities This winter marks the third year ot collaboration among the Arnold Arbore- tum, Olmsted National Historic Site, the Harvard Graduate School of Design, and a number of other sponsors to present a lecture series exploring our changing relationship with the Ameri- can landscape and natural environment. This year’s series will discuss the future of urban open space and examine the ongoing debate about how “nature” can best be shaped and managed as an integral part of the American city. All lectures are free and begin at 6:30 pm in the Piper Auditorium of the Harvard Graduate School of Design at 48 Quincy Street in Cambridge. The Arboretum extends its thanks to the Massachusetts Foundation for the Humanities for its support of the series. Maurits C. Escher, Night and Day, Philadelphia Museum of Art. Given by Mrs. Herbert C. Morris February 9: The Future of the Garden in America — Beyond the Wilderness and the Lawn Michael Pollan, Author of Second Nature February' 23: A Manifesto for the Charles River Sam Bass Warner, Jr., Urban Historian March 9: Regrounding Nature in the New City Catherine M. Howett, Professor, School of Envi- ronmental Design, University of Georgia March 23: Imagining the New Urban Park Diana Balmori, Principal, Balmori Associates 8 Karen Madsen Literature Cited 33 . 1980. Rhododendron cultivars, their nomenclature and international registration. Pp. 63-73 in J. L. Luteyn, ed., Contributions toward a classifica- tion of Rhododendron. New York: New York Bot. Card. Brickell, C. D., and B. Mathew. 1976. Daphne: The genus in the wild and in cultiva- tion. Woking, England: Alpine Garden Soc. , ed. 1980. International code of nomen- clature for cultivated plants — 1980. Utrecht: Bohn, Scheltema