Page 2 Tenshin-en arnoUia Moir Messervy Julie Volume 52 Number 3 Fall 1992 14 Magnificent Maclura-Past and Present John C. Pair

Arnoldia (ISBN 004-2633; USPS 866-100) is published 20 Our Native Pawpaw: The Next New quarterly, in winter, spring, summer, and fall, by The Commercial Fruit? Arnold Arboretum of Harvard University. Second-class M. Brett and Dorothy J. Callaway postage paid at Boston, Massachusetts. 30 Make Mine Mulch - Subscriptions are $20.00 per calendar year domestic, Peter Del Tredici $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 com- munication 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

Peter Del Tredici, Editor Judith Leet, Associate Editor

Amoldia is set in Trump Mediaeval typeface and printed by the Office of the University Publisher, Harvard University. Copyright © 1992, The President and Fellows of Harvard College

Front cover: The curious flowers of Asimina tnloba, the pawpaw. Photo by Al Bussewitz.

Back cover: The fall foliage of Lmdera obtusiloba growing at the Arnold Arboretum. This plant consis- tently produces spectacular clear-yellow autumn color. The red foliage of Sassafras albidum can be seen above and to the right. Photo by Peter Del Tredici.

Inside front cover: The fruit of Maclura pomifera, the Osage orange. From The Sylva of North Amenca by C. S. Sargent, drawn by C. E. Faxon.

Inside back cover: This gate, made of Japanese cypress (Chamaecyparis obtusa), was built in Kyoto and reassembled on site at Tenshm-en. Photo courtesy of the Museum of Fine Arts, Boston. Pawpaw flower buds. Photo by Rdcz and Debreczy. 2 Tenshin-en: A Japanese Garden at Boston’s Museum of Fine Arts

Julie Moir Messervy

An urban haven for contemplation that embraces two cultures.

For many Westerners, the idea of owning a senses a mixture of design prowess and acci- Japanese garden is an unreachable dream. dent. Equally impressive are the lushness Busy, stressed in their workaday world, they and quantity of the plantings: over 70 imagine returning home to a serene paradise species-1750 specimens in all-adorn the of ancient stones perfectly set in a bed of landscape, changing the feeling and form of moss, flanked by rippling waters of a koi the garden through the seasons. In early pond. Here, in this miniature world, they spring, the white-panicled flowers of can give voice to their inner thoughts, day- andromeda hang as tresses from the shiny dreams, and spiritual longings; they can green of the shrub’s leaves. Mid-spring into become their true selves in a garden of early summer brings a continuous bloom of beauty. azaleas in shades of white, fuchsia, rose, Few of us will have the space, find the salmon, and pale pink, hummocking as time, or have the money to create such a small hills at the feet of tall stones and sanctuary in our lives. How fortunate it is, lanterns. Early to midsummer brings the then, that the Museum of Fine Arts, Boston, purple, yellow, and white iris, standing in built just such a garden for all of us to expe- upright sheaths behind rocks. In fall, the rience and enjoy. Sitting within its walls, maples, azaleas, and enkianthus turn bril- closed off from busy Boston traffic and liant hues of red, yellow, and orange to mark passersby, one feels sheltered in an oasis, the onset of colder weather, before the snows paradoxically surrounded by, yet removed drape the garden in winter. One could attend from, present-day urban life and times. the garden every day and discover oneself One sits in a curiously transcendent anew through the continuously changing world, feeling the stones as venerable souls appearance of plants amidst the unchanging set with a modern freshness and vigor, rem- stolidity of the stone elements. iniscent of rocky shorelines of New England, A of Cultures yet universal in the abstract power of their Merging dry composition. At first, the visitor feels Tenshin-en, the Garden of the Heart of overwhelmed by the energy of the place, Heaven, is a 10,000-square-foot contempla- nearly 200 rocks, set here and there, and tive viewing garden located at the north side

The Japanese lantern located near the water basin at Tenshin-en. Photo courtesy of the Museum of Fine Arts, Boston. 4

The crushed gravel "sea" at Tenshm-en. Raking gives the effect of ripples on the water’s surface. Photo cour- tesy of the Museum of Fine Arts, Boston.

of the West Wing of the Museum of Fine ism with a feeling of beauty and repose that Arts, Boston. Completed in 1988, the garden evokes the New England landscape. Rocky is named in honor of one of the museum’s coastlines, deep forests, soft hillsides, and first curators of Asiatic Art-Okakura craggy mountains are abstracted and recre- Kakuzo, also known as Okakura Tenshin. ated to remind viewers of the beauty and Tenshin-en is one of New England’s few diversity of this region. The intent, according semipublic viewing gardens in the Japanese to Professor Nakane, the garden’s designer, style. A true Japanese garden, according to was to create in the garden "the essence of cultural traditions, derives-and takes inspi- mountains, the ocean and islands ... as I ration-from the landscape around it. In this have seen them in the beautiful landscape of spirit the project team of landscape artists New England." flew over the New England region in a small Each rock, plant, and paving stone was plane to gain a sense of its geography and aes- chosen from local materials and combined thetic qualities. The resulting garden is an with artifacts selected from the Museum’s interpretation of two cultures, combining the collection or brought from Japan. Together depth of meaning of Japanese garden symbol- these intermingle to create a contrast 5

Lookmg along the curved path towards the gate at Tenshin-en. Photo courtesy of the Museum of Fine Arts, Boston. between natural materials and human The Halvorson Company, a Boston land- objects and arrangements. scape architecture firm, was chosen to pro- duce the technical documents and details of Tenshin-en Origins necessary to build a garden of another cul- The Museum of Fine Arts, Boston, asked an ture in this country. Our mandate was to internationally known garden master from combine an acute sensitivity to the nuances Kyoto, Professor Kinsaku Nakane, to design of Japanese design with a full understanding and construct a Japanese garden as an impor- of the legal and technical requirements of tant addition to the museum’s world- building projects in this country. Also renowned Asiatic collection. Funds for the included in the team were various subcon- project were donated by the Nippon tractors from this country and from Japan, Television Network Corporation, Mr. Yosoji each of whom brought specialized training Kobayashi, Chairman of the Board. and craftsmanship to different aspects of the As the garden master’s project coordinator, project. The landscape contractor was my responsibility was to assemble a project Donald B. Curran, Incorporated of Ipswich, team to carry out his conceptual designs. Massachusetts. 6

The garden evolved through a style of col- Professor Nakane, in a calm and almost laboration quite different from normal casual way, would set one stone at the American landscape architectural practice. takiguchi (waterfall), the next stone on the The garden master’s concept and execution tsurujima (Crane Island), and the next in the were upheld by the efforts of every team foreground of the garden. He saw the final member in an atmosphere of unstinting result in his mind’s eye and worked around commitment to the creation of a work of art: the whole garden to balance his composition the Museum’s curatorial staff guided the gar- right from the start. As well as fitting into den process and provided and conserved the design as a whole, each stone grouping many of its artifacts; the Italian masons set had to be balanced in its own right-all of Kyoto roof tiles on its walls; the Japanese which Professor Nakane accomplished with carpenters built a traditional gate in Kyoto, split-second decisions. When the composi- dismantled it, and reinstalled it on site with tion was complete, nothing needed to be the American carpenters’ help. All upheld altered; the whole felt dynamic and yet bal- the master’s concept, in a collaboration of anced. the highest order. After he had set the stones, Professor On one of his trips to the site, Professor Nakane returned to Japan while the walls Nakane was present to set the critical ele- and new sidewalks were installed. On his ments that make up the structure of the gar- next trip to Boston he set fifty-two trees on den. To watch him was to see a true master the day he arrived, but unexpectedly at work. For six hot days in July, 1987, returned to Japan the following day, called Professor Nakane established the positions back because of a death at the Osaka of the rocks in the garden. Attending to an University of Fine Arts, which he heads. At image of power and beauty that existed only that point, his son and chief assistant Shiro in his sketches and in his imagination, he set Nakane took over and set the remaining almost two hundred stones. plantings, ornaments, and stepping stones, With the aid of a 100-foot hydraulic crane, and supervised the erection of the Japanese its highly attentive operator, and three land- gate. scape crews, the shape of the garden began to Professor Nakane returned one more time emerge. One by one, the boulders, filling for the opening of the garden on October 24, eight tractor-trailer trucks, were bound and 1988. At that time, he declined to speak but chained to the crane’s wire. Like the conduc- chose instead to paint a sign for the garden in tor of a symphony orchestra, Professor sumie-Japanese ink. Inscribed is ten, shin, Nakane would indicate to one crew how and en (with Chinese characters) in his own deep into the ground they should dig, and to beautiful calligraphic hand. Since then, another which way the stone should face- Tenshin-en has been opened to the public and where its head, feet, front, and back from spring through fall and is visited by should be positioned. The crew placed the thousands of people every year. stones, some weighing as much as eight tons, in the ground and made minute adjust- Design Features of Tenshin-en ments under Professor Nakane’s watchful Tenshin-en is designed as a viewing garden eye. All this was done without a word spo- in the karesansui style, harkening back to ken, as Professor Nakane speaks only Zen temple gardens of the fifteenth century Japanese. in Japan. Kare means "dry," san, "moun-

The plan of Tenshin-en at the Museum of Fme Arts, Boston. Reproduced courtesy of the Museum of Fme Arts, Boston. 7

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tain," and sui, "water"; thus it is a "dry them in their gardens. To the left is kame- mountain water" garden, or a dry landscape jima, the Tortoise Island; to the right is tsu- garden. Water is suggested by the raked rujima, the Crane Island. Looking carefully, gravel "sea," which unites all the landforms one can see the head, feet, tail, and flippers of the garden-the mountains, islands, and of the tortoise, and the head, wings, and tail rocky shoreline formed by mounded earth of the crane. and rocks. According to Professor Nakane, "The Tenshin-en relates to its surroundings by mountains and islands symbolize the nat- a technique called shakkei, that is, by bor- ural beauty of this region [New England], rowing and echoing the distant landscape and, at the same time, mean enduring pros- and bringing it into the garden walls. Curved perity and happiness for the Museum visi- shorelines and bridges within the garden tors." If one studies the garden’s design echo the lines of the Fenway landscape that features, the rocky coastline to the right abuts the museum on its north side, recalls the Maine Coast, and the two large designed by America’s premier garden mas- rocks on Crane Island suggest Mt. Fuji (on ter, Frederick Law Olmsted. Olmsted the right) and one of New England’s best designed parks and green spaces during the known peaks, Mt. Monadnock (on the left). late 1800s, creating Boston’s "Emerald Looking carefully, one can see a profile much Necklace," the park system that links open like that of New Hampshire’s "Old Man in space from Franklin Park to the Boston the Mountain" on the floating island Commons as one nearly continuous sweep between the Crane Island and the rocky of green. Although conceived and designed coast. The stepping stone path area is an on a scale far vaster than Tenshin-en’s minia- abstraction of deep forests, and the mossy ture landscape, Olmsted understood the hillside behind the Crane Island recalls the need to evoke a harmonious understanding softly forested landscape of New England. of nature, as he wrote in 1879: "We want a The Stones ground to which people may easily go after their day’s work is done, and where they In the Japanese garden, the stones are the may stroll for an hour, seeing, hearing, and backbone and provide the overall structure. feeling nothing of the bustle and jar of the Rocks from Topsfield, Boxford, and Rockport, streets, where they shall, in effect, find the Massachusetts, total about 390 tons. Each is city put far away from them." placed according to ancient rules and tradi- tions dating back to the Middle Ages of A Deeper Reading of the Garden Japanese history. A dark granite vertical Visitors who understand the garden’s sym- stone and base, carved in Japan, is located to bolism will probably have a richer experi- the left of the waterfall, and says Ten-shin- ence of it. The dry "waterfall" (takiguchi) to en in Chinese characters, a gift of the gar- the back and left of the garden represents the den’s donor, Yosoji Kobayashi. Buddhist concept of shumisen or Mt. The Wall and Gate Sumeru, a mythic mountain thought to sup- Japanese port the heavens above and the world below, The wall is a modern interpretation of a and around which the universe was believed Japanese mud-and-wattle wall, seen in tem- to be centered. The two "islands" in the left ple compounds and surrounding traditional and right center of the garden are two of the gardens all over Japan. This wall, varying in "Mystic Isles of the Immortals," Taoist height from five to seven feet, was con- mythical islands said to bring immortality structed of poured concrete mixed with a and prosperity to those who incorporated light colorant, which was then sandblasted 9

One of the curved budges which link the "islands" to the "mainland. Photo courtesy of the Museum of Fine Arts, Boston. to roughen the texture. The base band is of and eaves tiles. A special Museum of Fine granite from Deer Isle, Maine, resembling Arts emblem tile, onigawara, featuring the the facade of the museum’s West Wing. museum’s seal, was also made up and From the outside, one can see only a nar- grouted to the end wall at the Education row round cap of tiles of a simple design to Entrance. meld with the spare lines of the West Wing. The imposing Japanese gate is called From the inside, one sees the full slant of the kabuki-mon, meaning "hanging gate" (and roof that protects a typical wall from the ele- does not refer to the famous Japanese the- ments. These silver tiles are made of clay ater.) A traditional gate for a mountain castle baked four times rather than the usual two, or large palace in Japan, it was chosen as a in order to accommodate Boston’s more Japanese-style horizontal counterpoint to severe climate. An old Kyoto firm, architect I. M. Pei’s large concrete beam at Yokoyama Seiga Kojo, specializing in shrine the entrance to the West Wing. The gate is and temple roof tiles supplied the 1500 built of Japanese cypress, a wood with excel- pieces that make up the roof, including lent natural preservatives. Special design fea- round roof tiles, stacked tiles, beam tiles, tures of the gate are the 13-inch-wide post 10

Perennials in Tenshin-en Six hundred perennials adorn the garden. rum), goatsbeard (Aruncus canadensis), Ferns of many varieties are used with lady’s mantle (Alchemilla pubescens), iris hostas and liriope to soften the appear- [Iris ensata, sibirica, and cristata), gerani- ance of the rocks. Leatherleaf ferns as ums (Geranium endressi ’Johnson’s Blue’, well as lady, hart’s tongue, Japanese G. sanguineum), astilbes (Astilbe chinen- painted, Christmas, and maidenhair ferns, sis ’Pumila’, ’William Buchanan’), bleed- abound in the garden. Hostas include ing heart (Dicentra eximia ’Zestful’), wild ’Gold Standard’, ’Green Fountain’, ginger (Asarum europaeum), liriopes, and ’Francee’, ’Blue Cadet’, ’Nakiana’, and sedges (Liriope spicata, Carex comca ’Flavo Circinalis’, with five giant hostas ’Variegata’). One can also spot pachysan- featured outside the walls (’Halcyon’, dra (P. terminalis ’Cutleaf’) planted as a ’Christmas Tree’, ’Nigrescens’, ’Frances specimen near the water basin and step- Williams’, and ’Blue Angel’). Other peren- ping stone path. The groundcover moss is nials include bloodroot (Sanguinaria Polystrichum commune, known as hair- canadensis), trillium (Tnllium grandiflo- cap moss.

and beams (kasugi, or "umbrella wood" large stepping stone upon which one kneels curved beams above the two small doors), to partake of the water is called a maeishi, or the ornamental nail covers, and ironwork. "front stone"; the stone to its right is the The gate was constructed in Japan by yuokeishi, or "hot water container stone," Suzuki Komuten, carpenters who specialize on which such a container would be placed in building traditional Japanese structures. in winter so that guests could add hot water After being erected once for approval in to the basin to warm their hands. The stone Japan, it was disassembled and rebuilt in to the left is the teshokuishi, or "hand can- Boston. The wrought-iron fittings, hinges, dle stone," on which a guest might place a and nail covers, also fabricated in Japan, are portable candlestick when using the garden of traditional design. at night. The Water Basin The Stone Lanterns The water basin, or chozubachi, enables a Stone lanterns were originally used as votive visitor to ritually purify his or her body and lights placed in front of Buddhist temple mind as preparation for contemplating the buildings. In later years they played a more garden and for receiving inspiration and ornamental role and were designed specifi- renewal from its spiritual meaning. Similar cally for garden use-to light the path to a tea stone basins were used in tea gardens as ves- house or to light certain areas of a garden. sels for ritual cleansing before taking tea. Near the water basin is a small Japanese This chozubachi is in the fusen style, fu lantern of the Edo period (1603-1867), origi- meaning "to proclaim" and sen meaning nally located in the Japanese Court of the "spring of water." museum’s Asiatic Collection. It has a tall The stones around the water basin are mushroom-shaped "hat" and is placed so that arranged in the original Koho-an style. The it can cast light over the water basin at night. 11

In the northeast corner of the garden is a path for the viewer to take a visual rather kasuga-style lantern, a reproduction of one than an actual journey. These bridges, called from the Kawageta Temple, the original con- soribashi, or "curved bridges," are as long as sidered a "very important cultural property" 17 feet and weigh as much as 1.5 tons. by the Japanese Government. Dating from The 1311, the lantern is a very good example of Plantings late Kamakura-period (1185-1333) lanterns. It Over seventy species of plants give color and shows the then prevailing concern with texture to the garden. Cherries, Japanese power and beauty in its attacking lion and maples, and pines are all signature plants of peacock carvings. Single petals of lotus are a Japanese garden and serve as symbols of carved at the base, a Buddhist symbol of the the changing seasons. Tenshin-en is com- soul’s ascent from mud to the glory of flow- posed of a mixture of Japanese and American ering. species; such plants as Japanese Cryptomeria Just inside the gate is another kasuga-style combine with American holly to create a lantern, a reproduction of the main lantern new horticultural interpretation of an at the Joruri-ji Temple near Kyoto, carved ancient art form. about 1366. The shape of this lantern fol- lows the composition of the Kawageta Trees: Japanese maples, called kaede, or lantern but it is narrower overall: the lotus "frog’s hand" or momiji, are mainstays of a petals are taller, the window is smaller, and Japanese garden. Used to create a feeling of the curve to the roof is steeper. mountain scenery at the edge of a forest, A large Korean lantern in a fourteenth- they link open land to forested land. century style, originally located in the court- Broadleaf evergreen trees are generally not yard of the museum, is situated in the hardy in the Northeast, so American hollies, southeast corner of the garden. Outside the Ilex opaca, were used in place of some of the garden wall is a Meiji-period lantern, dating evergreen oaks that, in Japan, act as tall ever- from about 1880, featuring ornamental green screens to give the sense of a deep for- friezes of mountains and deer. est. Needle-leaf trees, including compact selections of the Canadian hemlock (Tsuga The Paths canadensis) and Cryptomeria japonica Japanese garden paths are based on the prin- ’Yoshino’, are used to create a lush back- ciple of shin-gyo-so. The path outside the ground to the waterfall and mountain path gate is of the shin, or "formal" style, the areas. Cryptomeria is part of the indigenous stepping stones are of the so, or informal vegetation in Japan and are planted exten- style, and the curved nobedan path is of the sively in holy areas such as shrine precincts. gyo style (somewhere between informal and Red pines (Pinus densiflora) and tanyosho formal in style). The cut stones on the pines (Pinus densiflora ’Umbraculifera’) are curved path are surrounded by black-washed used to highlight the islands. Mexican river stones set in mortar. This Deciduous trees used in the garden path brings one to the cut stone terrace on include Stewartia pseudocamellia, moun- which are three shogi benches of traditional tain ash (Sorbus decora), star magnolia design. The informal stepping stones paths (Magnolia stellata), and of course cherries: called tobiishi, take the visitor to the Korean the weeping cherry by the gate (Prunus sub- lantern, the water basin, or are used as an hirtella ’Pendula’), October cherries (Prunus alternate route back to the Japanese gate. subhlrtella ’Autumnalis’) and Sargent cher- There are also three bridges that link the ries {Prunus sargentii). The Japanese admire "islands" with the "mainland" and form a cherries as symbols of a life well-lived-they 12

Stone lanterns are used to light paths and highlight special areas of the garden’s design. Photo taken m 1988 and reproduced courtesy of the Museum of Fine Arts, Boston. bloom suddenly and abundantly, but are midseason bloomers of various colors: salm- gone nearly overnight, suggesting a good way on (’Guy Yerkes’), silver-pink (’Kaempo’), to face death as well. white with pink throat (’Geisha’), white (’Girard’s Pleasant White’, ’Polar Bear’), rose- Shrubs: The 1100 shrubs in the garden pro- red (’Vyking’), and the beautiful ’Purple vides its finished and colorful look. About Gem’. Late-blooming varieties include the 500 azaleas of many varieties provide color North Tisbury hybrids (’Wintergreen’, over two months in the spring. Early ’Yuka’, and ’Marilee’). Azaleas are pruned in bloomers include the Korean azalea (Rho- the karikomi, or cloud-form shape, to sug- dodendron poukhanensis) and varieties of R. gest the billowing forms of hills and to mucronulatum. The popular ’Delaware soften the base of the stones. Valley White’ azaleas and early reds Other shrubs used extensively are moun- (’Hinocrimson’ and ’Hinodegiri’) mix with tain laurels [Kalmia latifolia), andromeda 13

(Pieris japonica, P. floribunda), enkianthus rakes in lines parallel with the West Wing (Enkianthus campanulatus), kerria (Kerria wall. When the raker reaches an obstacle, japonica), daphne (Daphne burkwoodii such as a stone or island, he stands on it and ’Carol Mackie’), forsythia (Forsythia inter- rakes around it in a circle, continuing the pat- media ’Arnold Dwarf’), barberries (Berberis tern under the bridges and around all thunbergii, B. mentorensis), junipers [Ju- detached stones. Finally, the raker follows the niperus procumbens ’Nana’, J. chinensis edge of the garden’s "sea" around the perime- ’Sargenti’), euonymus (Euonymus alatus), ter until meeting the gate. The abstract lines holly (Ilex pendunculosa), and dwarf spiraea of "water" are most apparent during rainy or (Spiraea japonica ’Little Princess’). cloudy days, or when the textures are empha- sized by a thin veneer of snow. Maintenance Tenshin-en is frequented by viewers com- Contrary to popular opinion, a Japanese gar- ing to learn about another culture’s garden den is not a low-maintenance landscape. art, to enjoy the verdant atmosphere, or to One day a week throughout the garden’s seek a moment’s peace. In the Garden of the open season, a maintenance crew comes to Heart of Heaven, visitors will feel the truth tend the garden. Every week the crew prunes of the words of Okakura Tenshin who once certain trees and shrubs, weeds the moss, said, "One may be in the midst of a city, and and rakes the gravel. Other gardening chores yet feel as if one were far away from the dust occur at specific intervals during the year: and din of civilization." moss is trimmed for propagation, perennials are cut back or divided, fertilizers or horti- Tenshin-en is open to Museum of Fine Arts cultural sprays are applied, hemlock bark visitors from April to November, Tuesdays mulch is spread; azaleas are deadheaded and through Sundays, from 10 a.m. to 4 p.m. also pruned at least twice a year to maintain their shape and size. Viewers are always curious about how the The designer of the Arnold Arboretum’s Linda J. garden is raked. Crushed granite gravel from Davison Memorial Path and the project coordinator of Mt. Airy, North Carolina, represents the Tenshm-en during its construction, Julie Moir Messervy "sea" of the garden’s landscape. A heavy six- is a landscape designer living in Wellesley. She is author of Contemplative Gardens (Howell Press, 1990) and is tine rake is used to the effect of give ripples currently finishing a new book, The Inward Garden, to on the water’s surface. Starting from the near be published by Little Brown and Co. m September right-hand corner of the garden, the crew 1993. Magnificent Maclura-Past and Present

John C. Pair

New cultivars of the Osage orange have stimulated interest in this distinctive native tree.

The Osage orange, Maclura pomifera, has a kansas, and parts of Louisiana (Smith and long and interesting history of use by both Perino, 1981 The species is often referred to Native Americans and early pioneers (Sand, as hedge apple, or just "hedge," from its 1991 Its wood was once in demand for mak- common use as hedges and windbreaks in ing hubs and wheel rims for horse-drawn the plains states. Dunbar and Hunter sug- vehicles, mine timbers, posts, and other uses gested the idea of cultivating Osage orange where resistance to rotting was important. as a hedge to President Thomas Jefferson Its decay resistance is due to the chemical upon return from their expedition to the Red 2, 3, 4, 5-tetrahydroxystilbene, located in the River in 1806 (Morton, 1967). wood and toxic to many fungi (Smith and The common name of the plant comes Perino, 1981).). from its globular, characteristic fruit, about Perhaps the species is best known as a the size of a large orange, borne on female "living fence" because of its stout thorns on trees of this dioecious species (Figure 1). The zigzagging branches, ease of propagation, French found the Osage Indians making rapid growth, and tolerance to heat, drought, their bows from its wood and called it bois and wind. Osage orange was first cultivated d’arc (meaning wood-of-the-bow). Such in the South in the early 1800s. The plant bows were so highly regarded by Indian reached Jacksonville, Illinois, by 1830, tribes to the north that they were considered brought north by Professor Jonathan Turner, worth a pony and a blanket in trade. a biology teacher from Illinois College, and Recently the tree has been advocated as an promoted through the efforts of John A. urban tree for difficult planting sites (Powell, Wright, editor of The Prairie Farmer. By 1847 1979). Turner was convinced that Osage orange was the best fencing material available, describ- The Champion Tree ing it as "horse high, bull strong, and pig The champion Osage orange tree in the tight"; it functioned as a fence long before United States was reported in 1939 to be the invention of barbed wire, which did not located in Charlotte County, Virginia; it come into wide use until 1875 (Dick, 1975). measured 15.5 meters (50.9 feet) high, with Maclura pomifera, a member of the mul- a circumference of 7.5 meters (24.5 feet) and berry family (Moraceae), grows best in the a spread of 28.2 meters (92.5 feet) rich bottomlands along the Red River (Collingwood, 1939). Recent correspon- between Texas and Oklahoma. It also occurs dence has indicated that this same tree, naturally across southern Missouri, Ar- although somewhat in decline, is still on IS.1;

Figure 1 ’I~pical /rujt and thorns of Maclura pomifera, both undesirable when the tree is planted for land- scape use. the front lawn of the restored home of crown spread and a 4.8-meter (15.8 feet) cir- Patrick Henry, near Red Hill, Virginia, and cumference. Although doubts have been is now nearly 18 meters (59 feet) high with a expressed about the hardiness of this south- crown spread of 30.5 meters (100 feet) and a ern species, it has survived as far north as trunk diameter of 2.7 meters (9 feet) (Figure the Platte River in central Nebraska (Dick, 2). The Henry family reports that the fam- 1975). Large specimens occur across south- ily physician present when Patrick Henry eastern Iowa and central Illinois and Ohio, died on June 6, 1799, became so upset at not and it has also been planted along the West being able to save the legendary patriot that Coast. Internationally, it has been reported he went outdoors and "threw himself under- growing in the British Isles, France, neath a large tree, weeping bitterly" (Daily, Germany, Italy, the Netherlands, Portugal, 1983). The Osage orange is thought to be the Romania, Russia, Switzerland, and Aus- "large tree" mentioned, a living landmark of tralia (Spaulding, 1956). another era. After the Osage orange became widely The largest Osage orange in Kansas grows planted as fencing around small farms, it in Labette County and measures 18 meters quickly invaded the prairies, occurring as (59 feet) tall with a 21.3-meter (70 feet) small, pure stands or with mixed hardwoods; 16

Figure 2. The champion Osage orange tree at the home of Patrick Henry in Charlotte County, Virginia. The tree is nearly sixty feet tall, witha nine-foot trunk diameter. it moved into the eastern states, becoming Kansas State University has been identifying naturalized in abandoned fields. The species and evaluating thornless selections for over has no natural pests. twenty-five years (Pair and Keen, 1980). The first introduction made in the mid-1970s Thornless and Fruitless Selections was ’Pawhuska’, named after an Osage Although Rehder (1967) reported a thornless Indian chief. The most recent release is variety of the Osage orange, Maclura ’Wichita’ (Figure 3), a thornless male selec- pomifera var. inermis, such specimens are tion found growing near Wichita, Kansas uncommon, and some horticulturists sug- (Pair, 1991)./. gest that they are merely mature specimens Other selections propagated from large of trees that were typically thorny when specimens located in Oklahoma, Kansas, - they were more juvenile. However, isolated and Iowa continue to be evaluated. Quite thornless trees have been identified, and a promising is one called ’Whiteshield’, found few are creeping into the commercial trade. growing along Whiteshield Creek, and 17

named after a Cheyenne Indian chief. The tree has glossy, cordate-shaped leaves (Figure 4) and was discovered by John Flick near Hammond, Oklahoma. Another large male specimen without thorns, found by Al Ferguson growing in an old nursery near Denmark, Iowa, is being propagated for com- parison with nine other clones at the Horticulture Research Center in Wichita, Kansas. Propagation Osage orange is easily propagated in a variety of ways. Seedlings, traditionally used for windbreaks or as understock for improved selections, are grown from stratified seed removed from the large, leathery fruit col- lected in the fall. Seed slip easily from the pulp if allowed to ferment in water for sev- eral days. Stratification for 30 to 45 days at 4 degrees Centigrade (40° F) is usually suffi- cient to break dormancy so seed can be planted in the greenhouse in January or February. If sown outdoors in the fall, ger- mination will occur in April or May the fol- for lowing spring. Seedlings large enough Figure 3 A ten-year-old specimen of Maclura can be T-budding produced by mid-August. pomifera ’Wichita’, a thornless, male cultivar. Budding can be done in August using vig- orous, current season’s growth directly from any superior plant. Such buds will remain shoots, fifteen centimeters (6 inches) long, dormant until forced out the following April taken in May or early June and placed under or May. Alternatively, dormant scionwood intermittent mist, will root in five to six can be collected during winter and stored for weeks. Rooting hormones greatly increase June budding once bark slips on the under- the percentage and the numbers of roots pro- stock. duced. Concentrations of indolebutyric acid Bench grafting is also easily accomplished (IBA) ranging from 2,500 to 5,000 parts per using either a whip and tongue or cleft graft million are usually adequate. The commer- in midwinter. Grafts should be allowed to cial talc formulation Hormodm® No. 2 callus six weeks at near 12 degrees (3,000 ppm) works well. Softwood cuttings Centigrade (55° F) before potting up or lin- ready for potting in August need winter pro- ing out in the spring. The rootstock should tection before lining out the following be the same size as the scions used, or larger. spring. Wrapping with grafting tape or masking tape Hardwood cuttings can also be propagated secures the union until callusing occurs. easily with wood collected from January to Cuttings, both softwood and hardwood, March. With this method, plants of suffi- are commonly used to propagate thornless cient size can be produced for lining out the and fruitless selections vegetatively. Tender same season. Pair and Khatamian (1984) 18

Figure 4. A fruitless and thornless selection of Maclura with glossy, cordate-shaped leaves. found basal stem portions rooted better than strong tendency for multiple stems to occur terminal sections when taken off mature in this species, cuttings can be grown for one trees. Wood collected in winter should be season without pruning or training. If the cut into six- to eight-inch cuttings, dipped in plant is cut back to a single bud near the base 5,000 to 10,000 ppm IBA, and placed over the following spring (as in propagation by bottom heat near 21 degrees Centigrade budding), a strong central leader can be pro- (70°F) in a cool greenhouse (13 to 18 degrees duced to form a better, single-stemmed tree. Centigrade [55-65° F]). The rooting medium Osage orange has seldom been used as a can be either perlite or a mixture of perlite common residential tree. Its wide-spreading and peat in a two-thirds to one-third ratio, root system requires ample space, but its and should be kept moist, but not too wet. rustic beauty-particularly when the glossy Bottom heat allows callusing and rooting to green leaves turn yellow in autumn-can occur before leaves emerge from the cuttings provide shade and ornamental value to parks (Figure 5). and landscapes and at the same time sym- Cuttings taken as late as March 1 often bolize the American frontier. root in three weeks and can be potted up in As improved selections become available eight weeks-until of sufficient size for lin- and the demand for stress-tolerant, pest- ing out in early summer. Since there is a resistant trees increases, greater use may be 19

American Desert Lincoln: Nebraska State Historical Society, pp. 72-81.

Morton, C. V 1967 Freeman and Custis account of the Red River expedition of 1806, an overlooked publication of botanical interest. Journal of the Arnold Arboretum 48 431-459.

Pair, J. C 1991. Maclura pomifera’Wichita’. Amencan Nurseryman 174 (8): 146.

- - and R. A. Keen, 1980. Propagation of thorn- less-fruitless selections of Osage orange. Proceedmgs of the International Plant Propagators Society 30: 348-353.

- - andH.Khatamian 1984 Rooting of thornless Osage orange by hardwood cuttings as affected by IBA concentrations and stem por- tion. The Plant Propagator 30(1) : 6-7.

Powell, T. 1979 Taming the Osage orange. The Avant Figure 5. Rooted hardwood cuttings of Maclura after Gardener 2(13): 1. four weeks of bottom heat anda treatment of 5,000 ppm IBA Rehder, A. 1967. Manual of Cultivated Trees and Shrubs New York: Macmillan Co

S. A tree the made of male Maclura cultivars. From the Sand, 1991. history: Osage orange. American Horticulturist 70(10): 37-39. windswept prairie to the inner city, this tree may fill the need for those difficult planting Smith, J. L., and J. V. Permo. 1981. Osage orange sites where few other species can survive. (Maclura pomifera): history and economic uses. Economic Botany 35: 24-41.

References Spaulding, P. 1956. Diseases of North American Forest Trees Planted Abroad USDA Handbook 100. Collingwood, G. H. 1939. Osage-orange. Amencan Forests 45: 508-510

Daily, P. 1983. Osage orange at Red Hill: tale of a tree. Virginia Forests 39(3): 22-23. John Pair is a Research Horticulturist for Kansas State University at the Horticulture Research Center in Dick, E. 1975. Fences. In Conquenng the Great Wichita, Kansas. 20 Our Native Pawpaw: The Next New Commercial Fruit?

M. Brett and Dorothy J. Callaway

Asimina triloba can add a distinctive look to your garden and a tropical taste to your table.

If someone told you about a tree bearing emerged. The flowers are protogynous, that fruits that are delicious and exotic in flavor, is, the stigmas in a given flower mature custard-like in texture, and larger than any before the stamens. Flower petals are other native to the United States, you would arranged in two whorls of three (or more probably assume that this fruit was already rarely, four). The fruits are cylindrical, popular in the marketplace. If you learned many-seeded berries, usually ranging in that this same tree possessed large, highly length from 2 to 9 centimeters (1-4 inches), ornamental, dark-green leaves that turned a although some specimens of A. triloba bear brilliant gold in the autumn, you would sus- fruit as long as 15 centimeters (6 inches). pect that you had probably seen it in many Table 1 provides a comparative list of yards. You would, however, be mistaken in Asimina species, their synonyms, flowering both cases. The tree in question is the native and fruiting times, and other plant charac- pawpaw, Asimina triloba. But why is a fruit teristics. with such potential not already a commer- The most recent taxonomic study of the cial crop? How can the pawpaw benefit from genus Asimina was carried out by Kral what we know of the commercial develop- (1960). His treatment is widely followed, ment of other fruit crops? except for one species that Kral calls A. spe- ciosa, but that is more commonly referred to and Species Taxonomy in the literature as A. incana or A. incarna. The genus Asimina has the northernmost We believe A. incarna to be the legitimate range within the primarily tropical family, name of this species. Detailed distribution the Annonaceae. It includes eight species maps for species in the genus Asimina are and one named hybrid, all native to temper- provided by Callaway (1990). ate North America. Each of the eight species in the Genus Asimina and one hybrid of Asimina are briefly Species described below and in Table 1. Either decid- Asimina incarna, a small shrub with obo- uous shrubs or small trees, Asimina species vate leaves and white flowers, is native to produce flowers in the spring, often before sandy ridges and old fields from central the alternately arranged leaves have Florida north to southeastern Georgia.

Asimina tnloba, from The Sylva of North America by C. S. Sargent. Drawn by C. E. Faxon. 22 23

A. pygmaea, a dwarf shrub with obovate or oblanceolate leaves and maroon flowers, is native to flatwoods and savannahs from cen- tral Florida to southeastern Georgia.

A. reticulata, a shrub with oblong or ellip- tic leaves and white flowers, is native to most of the Florida peninsula.

A. tetramera, a shrub with oblanceolate or elliptic leaves and maroon flowers, is native to coastal sand dunes in the area of Martin and Palm Beach counties, Florida.

A. x nashii, the only named Asimina hybrid, is a naturally occurring cross between A. mcarna and A. longifolia. Described by Kral as occurring where the ranges of the two par- ent species overlap, it is a shrub with white flowers; its leaves are intermediate in size between the two parents. Although other Asimina hybrids were discussed by Kral (1960), only A. x nashii was named.

Asimina triloba, by far the most widespread and northernmost species of Asimina, deserves special attention. A shrub or small The attractive tnloba. Photo foliage of Asimina by tree with maroon it is native to Al Bussewitz. flowers, most of the eastern half of the United States from Florida to Ontario, west to Nebraska A. longifolia, a small shrub with narrow and Texas (see range map). The fruit of A. leaves and white flowers, is native to flat- triloba, unlike that of most of the other woods and sand ridges from northeastern species, is palatable, large, and deserving of Florida to southeastern Alabama. commercial exploitation. Horticulture of Asimina A. obovata, a shrub or small tree with obo- triloba vate leaves and white flowers, is native to Because of transplanting difficulties, paw- dry sand ridges, coastal dunes, and ham- paws are best started as seedlings in deep mocks throughout most of peninsular containers and grown to a height of 0.6 to 0.9 Florida. meters (2-3 feet) before they are transplanted to the field. Seedlings should be protected A. parviflora, a large shrub or small tree, from direct sunlight for the first year of with oblong leaves and maroon flowers, is growth because of their sensitivity to ultra- native to rich woods, lime sinks, and alluvial violet light. In their second and subsequent soil of coastal hammocks from Florida to years, however, plants should be placed in southeastern Virginia, west to Tennessee full sun for best fruit production (Willson and eastern Texas. and Schemske, 1980). The limited cultural 24

flower loss in some years. A number of ver- tebrates (foxes, opossums, and squirrels) are known to eat pawpaw fruit. Propagation Pawpaw seed should not be allowed to dry out before planting. Small quantities are placed in polyethylene bags containing damp sphagnum moss. Cold stratification at 2 to 4 degrees Centigrade (35-39°F) for 60 to 100 days is recommended (USDA, 1948). Rate of germination is improved by bottom heat (27 to 30 degrees C [80-86°F]) and shading (Callaway, unpublished; Evert and Payne, 1991; Peterson, 1991). The most reliable method of vegetative propagation is chip- budding. Root cuttings have also been suc- cessful (USDA, 1948). Tissue culture and softwood propagation methods have not been satisfactorily developed. Varieties Compilations of information on past and present varieties of Asimina triloba have appeared in reports by Callaway (1990, 1993) and Peterson (1991). Much of the informa- the a m South Growing m understory of forest tion available on varieties is and Carolma, the alternate the subjective arrangement of foliage of of value. so-called vari- the pawpaw is both obvious and distinctive. Photo questionable Many by Peter Del Tredici. eties are trees that were named by their owner and reported in the literature of vari- ous fruit-grower societies, but never propa- information available for pawpaw is summa- gated for distribution. However, until rized by Callaway (1990, 1993). properly conducted variety trials are carried out, these are the best sources of informa- Diseases and Pests tion available. Of the sixty-eight varieties Diseases of Asimina include flyspeck listed by Callaway (1993), commercial sup- (Zygophiala jamaicensis) and a leaf spot pliers are known for nineteen. However, caused by a complex of pathogens (Myco- only ’Sunflower’ is listed by more than two centrospora asiminae, Rhopalocomdium nurseries. (It is listed by six.) Eight are listed asiminae, and Phyllosticta asiminae) (Nasu by two nurseries and 10 by only one. ’Davis’, and Kunoh, 1987; Peterson, 1991). None of ’Overleese’, and ’Sunflower’ are probably the these diseases cause significant damage to most widely grown varieties. ’Overleese’ and the fruit. Insect pests include two leaf feed- ’Sunflower’ are generally considered among ers, Eurytides marcellus and Omphalocera the best selections currently available. munroei (Damman, 1986), and one pedun- Selected from the wild around 1950 in cle borer, Talponia plummeriana (Allard, Rushville, Indiana, ’Overleese’ bears fruit 1955). T plummeriana may cause serious weighing approximately 350 grams (12.3 25

The range of Asimma tnloba, the pawpaw. From Atlas of United States Trees, Vol. 4, Minor Eastern Hardwoods. 1978. USDA Misc. Publ. 1342. ounces) and ripens about the first week of ties (Alkofahi et al., 1989; Rupprecht et al., October in Michigan. ’Sunflower’ fruits, 1986; Rupprecht et al., 1990). Pawpaw also somewhat smaller, weigh approximately 250 develops into a very handsome ornamental grams (8.8 ounces) and ripen in Michigan at plant. In the open, trees assume a pyramidal about the same time as ’Overleese’. form. Throughout the summer they are ’Sunflower’ originated in Chanute, Kansas. adorned with large, drooping, dark-green leaves which turn brilliant golden in the fall. Utilization and Prospects Despite the fact that pawpaw is native to Currently, pawpaws are primarily consumed the United States, its commercialization is as fresh fruit. They may also be processed apparently more advanced in other coun- into ice creams, juices, and other products as tries, such as Japan and Italy. We are aware of are their Annona relatives. In addition to only one commercial planting in the United food uses, scientists at Purdue University States and their plants are still too small to have isolated compounds from vegetative bear fruit. Fortunately, this lack of interest parts of the pawpaw that exhibit highly seems to be changing. Pawpaw plants have effective pesticidal and anti-tumor proper- recently been selling briskly in the nursery 26

The fmit of Asimina tnloba hangmg from a tree at the Arnold Arboretum. Photo by Al Bussemtz. trade, particularly grafted varieties, and none In the Old World, superior varieties of these of the nurseries selling pawpaw varieties fruit had been selected over several centuries have been able to meet the demand for and propagated widely by grafting. Therefore, plants within the last two years. Although these improved fruits were more widely adequate assessment of market demand for grown than unimproved native fruits. new crops is quite difficult, recent trends Although exceptional specimens of paw- indicate that the prospects for successful paws can be found in the wild, the proportion commercialization of this fruit appear to be of superior plants, as with any wild fruit improving. (apples, peaches, and pears included), is small. Historically, many years are required Difficulties in New Crop Introduction for exceptional specimens to become widely Asimina triloba was widely used by Native distributed. Early efforts at collecting excep- Americans before European settlement. tional specimens were made by the Amer- Although early settlers also used pawpaw, ican Genetic Association (Anonymous, 1916, they also brought fruit-such as apples, 1917) and by a few individuals, most notably peaches, and pears-with them from Europe. Dr. G. A. Zimmerman (1938, 1940, 1941) of 27

A selection of Asimma triloba producmg exceptionally large fruits Photo by Brett Callaway.

Harrisburg, Pennsylvania. Unfortunately, Domestication of the blueberry (Vaccinium many specimens identified during this spp.) has taken place entirely in the twenti- period were lost during World War II. In eth century (Galleta, 1975). The first com- recent years renewed efforts by a few indi- mercial plantings were established in Florida viduals have led to a resurgence of popular in the late 1800s (Lyrene and Sherman, 1979) interest in pawpaws. and breeding work began in the early 1900s. The improvement of crops through breed- ’Tifblue’, probably the most widely grown ing is particularly slow for tree crops because rabbiteye type of blueberry (V. ashei) is of the long intervals between generations. derived from parents collected from the wild Often a breeder is only able to evaluate five (Austin, 1985). Kiwi (Actinidia chinensis) is or six generations in an entire career. When another example of a recently developed one considers that a corn breeder can evalu- fruit enjoying commercial success. There- ate three generations a year, the comparative fore, Asimina germplasm collections made difficulty of developing new varieties of fruit in recent years by Peterson (1986) and crops from trees or shrubs becomes obvious. Callaway (1991), and a number of superior However, there have been successes. varieties collected from the wild (listed by 28

Callaway, 1993), provide the foundation for Callaway, M. B. 1990. The pawpaw (Asimma tnloba). State Publication CRS- work to Kentucky University pawpaw breeding begin. HORT-901T. Lessons from Other Crops Callaway, M. B. 1991. Germplasm collection using pub- Important lessons are to be learned from the lic contests-the Asimina tnloba example. early efforts at commercialization of blue- Hortscience 26: 722. berries. Between 1921 and 1925, a boom in M. B. 1993. (Asimma tnloba), a the Florida market took Callaway, Pawpaw blueberry place. "tropical" fruit for temperate climates. In J. Hundreds of thousands of plants were dug Janick and J Simon (eds.). New Crops from the wild and planted in commercial Exploration, Research, Commercialization fields. The extreme variation in fruit qual- New York: John Wiley. from these wild would be the ity plants (as Damman, A. J. 1986. Facultative interactions between case wild led to a decline in for any fruit) two lepidopteran herbivores of Asimina demand for the Florida fruit and caused the Oecologia 78: 214-219. industry to shift to more northern parts of D. and A. 1991. Germination of the U.S. where superior varieties were clon- Evert, R., J. Payne. and and Asimina tnloba and A. parviflora. ally propagated grown (Lyrene Hortscience 26: 777. Sherman, 1979). The great demand for paw- paws in recent years has led to a shortage in Galleta, G. J. 1975. Bluebernes and cranberries. In J. plants of superior varieties. Customers are Janick and J. N Moore (eds.). Advances in Frmt Breedmg, pp. 154-196. West Lafayette, on lists, sometimes for years. placed waiting Indiana: Purdue University Press Under these conditions, as in the boom years of the Florida blueberry industry, the temp- Kral, T. 1960. A revision of Asimma and tation to plant seedlings of variable quality Deenngothamnus (Annonaceae). Bnttoma is great. However, this practice is short- 12(4):233-278. and can a sighted potentially destroy Lyrene, P. M., and W. B. Sherman. 1979. The rabbiteye nascent industry. blueberry industry m Florida-1887 to 1930- with notes on the current status of abandoned Economic 33:237-243. References plantations. Botany Alkofahi, A., J. K. Rupprecht, J. E Anderson, J. L. Nasu, H., and H. Kunoh. 1987. Scanning electron McLaughlin, K L. Mikolajczak, and B. A. microscopy of flyspeck of apple, pear, Scott. 1989. Search for new pesticides from Japanese persimmon, plum, Chinese qumce, higher plants, pp. 25-43. In J. T. Arnason, B. J. and pawpaw. Plant Disease 71:361-364. R. Philogene, and P. Morand (eds.). American Chemical Society Symposmm Senes 2, No. Peterson, R. N. 1986. Research on the pawpaw (As1mma 387. tnloba) at the University of Maryland. Northern Nut Growers Association Annual Allard, H. A. 1955. The native pawpaw. Atlantic Report 77: 73-78. Naturalist 10(4): 197-203. Peterson, R. N. 1991. Pawpaw {Asimma). In J. N. Moore Anonymous. 1916. Where are the best papaws? Journal and J. R. Ballington (eds.). Genetic Resources of Heredity 7 291-296. of Temperate Frmt and Nut Crops, pp. 567- 600. International Society for Horticultural Anonymous. 1917. The best papaws Journal of Science, Wageningen, The Netherlands. Heredity 8(1)’21-33. Rupprecht, J. K., C.-J. Chang, J. M. Cassady, and J. L. Austin, M. E. 1985. Rabbiteye blueberry breeding. McLaughlm. 1986. Asimicm, a new cytotoxic Unpublished mimeo. and pesticidal acetogenm from the pawpaw, 29

Asimma tnloba (Annonaceae). Heterocycles Growers Association Annual Report 29 :99- 24:1197-1201. 102.

Rupprecht, J. K., Y -H Hui, and L. McLaughlin 1990. Zimmerman, G.A. 1940. Further report on the papaw. Annonaceous acetogemns a review. Journal Northern Nut Growers Association Annual of Natural Products 53:237-278. Report 31 133-134. Zimmerman, G. A. 1941. Hybrids of the American U. S. Department of Agriculture. 1948. Asimma tnloba papaw. Journal of Heredity 32(3):83-91. (L.) Dunal, pawpaw. Woody-Plant Seed Manual. U.S. Dept. of Agriculture Misc Pub. 654.

Willson, M. F., and D. W. Schemske. 1980 Pollinator M Brett Callaway is Tropical Germplasm Manager for limitation, fruit production, and floral display Pioneer Hi-Bred International and Adjunct Assistant in pawpaw [Asimma tnloba). Bulletm of the Professor of Horticulture at the University of Kentucky. Torrey Botamcal Club 107:401-408 Dorothy Callaway is a freelance horticultural writer and author of The World of Magnolias, soon to be pub- Zimmerman, G. A. 1938. The papaw. Northern Nut lished by Timber Press, Portland, Oregon. Make Mine Mulch

Peter Del Tredici

Using mulch in the garden not only reduces maintenance, but also contributes to the overall health of the plants.

The use of organic mulches in landscape sit- tilth and water-holding capacity, and by uations mimics the natural processes that increasing soil aeration. Mulch is the most occur in deciduous forests where a "blanket" cost-effective way of improving the com- of leaves is deposited on the forest floor pacted condition of many urban soils. every fall. Leaves not only act to insulate the soil during the winter but also are the mech- 4. Adds Mineral Nutrients anism by which carbon and mineral nutri- As organic mulching material decays, min- ents are recycled through the ecosystem (see eral nutrients are absorbed by symbiotic The Organic Matter "Recycle" flow chart). mycorrhizal fungi, which pass them on to In the list below I have summarized the prin- plants in "exchange" for carbon (see flow cipal benefits of mulch from the gardening chart). These nutrients, including phospho- perspective, along with some cautions about rus in particular, are essential for the healthy its use. growth of plants. Benefits of Organic Mulch 5. Moderates Soil Temperature 1. Conserves Water Mulch helps protect the root zone of plants The most immediate effect of mulch is to from fluctuations in temperature. In sum- reduce water evaporation from the soil sur- mer, the soil under mulch is both cooler and face. By protecting the soil surface from the more uniform in temperature than bare drying effects of the sun and wind, mulch ground. In winter, mulch can act as an promotes water conservation. important soil insulator, particularly in years when there is no protective snow 2. Inhibits Weed Growth cover. By reducing soil temperature fluctua- A one- to two-inch layer of mulch will sup- tions, mulch also helps to prevent small press the growth of many weeds, especially plants from being heaved out of the ground annuals, thereby reducing the amount of during the winter. weeding time required. 6. Reduces Soil Erosion 3. Improves Soil Structure Soil covered with mulch is better able to Organic mulch acts as a source of carbon for absorb rainfall than bare soil, thereby reduc- soil decomposers, which turn it into humus. ing soil erosion, particularly on steep slopes. Humus benefits the soil by improving its (continued on page 32) 31

The Organic Matter "Recycle" 32

Problems With Mulch should be the maximum depth with woody 1. Can Cause Temporary Nitrogen plants. With herbaceous perennials, too Deficiency much mulch can lead to rot problems, par- a wet season. Because of the high carbon-to-nitrogen con- ticularly during growing tent ratio of most organic mulches, they Conclusion should always be top-dressed with a light From the mulch sprinkling of an all-purpose garden fertilizer gardening perspective, accounts for the of (such as 5-10-5) in the spring. Supplemental improved growth plants in two it conditions for nitrogen not only speeds up the decomposi- ways: first, improves the and of beneficial tion process, but also serves to minimize the growth development temporary translocation of nitrogen from the soil microorganisms by providing them with soil to the mulch layer by fungal decom- both carbon and mineral nutrients; and sec- it increased root posers. ond, promotes growth by increasing the water-holding capacity of soil 2. Can Provide Habitat for Herbivorous and improving its tilth. The use of organic Animals mulches in the garden promotes the same Mulch provides excellent habitat for voles harmonious interactions between plant roots and soil that occur and other rodents, as well as for slugs and microorganisms in our native forests. snails, making control measures more diffi- naturally cult than they would be if the soil were bare. 3. Can Be Applied Too Thickly Peter Del Tredici has recently been to the On too much mulch can be appointed young plantings, position of Assistant Director for Living Collections at detrimental by inhibiting water penetration the Arnold Arboretum. He has served as Editor of and air flow. In general, two inches of mulch Arnoldia for four years. NEWS

from the Arnold Arboretum

A Mission Reaffirmed

Robert E. Cook, Director

historical mission of the ArnoldThe Arboretum has been captured in the story of E. H. "Chi- nese" Wilson, vividly recounted by Steve Spongberg in his wonderful book about botanical exploration, A Reunion of Trees. In a disastrous colli- sion with a rockslide on a mountain trail in central China, Wilson suf- fered a severely broken leg that re- quired three operations. Despite this, he managed to return to Bos- ton with 1,285 packets of seeds and more than 50,000 pressed and dried E. H. Wilson began bis first Arboretum-sponsored expedition with the purchase of a herbarium specimens. As a result houseboat for travels on the Yangtze River. Pictured here with its crew in 1907, the craft there grows today, on the south side " was christened ’The Harvard. of Bussey Hill, accession number 7272, a magnificent specimen of the public education, about the biol- Dr Wen is examining an old Sand Pear (Pyrus pynfoha) that first ogy of trees. scientific problem: Why do so many came to this country in seed lot 395 of native to eastern The modern execution of this species plants collected by Wilson near Ichang, North America also have re- roots in the closely China. mission, and its heritage lated sister in east- is embodied in the work species growing In 1988 the President and of Wilson, ern Asia? Is this an co- of Dr. a evolutionary Fellows of Harvard College reaf- Jun Wen, Putnam Research Fellow at the Arboretum For the incidence, or were these species once firmed the historical mission of two months she has travel- part of widely distributed ancestors? the Arboretum: past been With her collections of tissue ing m her native China to collect living 2022 To maintain and curate a docu- from the Arnold Arboretum and seeds, prepare herbarium specimens, mented collection of woody plants from distant locations in Dr. and sample living tissue, which is China, hardy in the Boston climate; Wen will be the of frozen in liquid nitrogen for later using techniques 2022 To study such plants through analysis These collections will molecular biology to isolate DNA maintenance of a library and her- complement comparable collections from her specimens and compare the barium for research and of these re- teaching; she gathered at the Arboretum last genes apparently closely lated these 2022 To give instruction, including spring. species. By combining (continued on page 2) (continued from page 1) results with traditional morphologi- cal and paleobotamcal evidence found in the herbarium and library collections of the Arboretum, she will be able to reconstruct the his- tory of divergences that created these groups and come to a much more fundamental understanding of their evolutionary relationships. Dr. Wen also collected and shipped seeds of a number of Asian species to the Arboretum, some of The Arnold Arboretum Associates conducted their Tenth A nnual Rare Plant Auction on which have never been grown in this September 20. Shown here are some of the volunteers whose hard work made the event country before. Of special interest run so smoothly. They, and many others, deserve congratulations and a big thanks for a are propagules of Aralia henryi and tradttton of excellence that has brought people and plants together in support of the Arnold Halesia matgregom. They have been Arboretum. logged into our computer database for future germination and planting A Federal Grant underlie the LEAP curriculum. Par- on the grounds There, beside the will mentor others in their original collections of Wilson, they for LEAP ticipants home schools, introduc- will critical mate- ultimately someday provide Dtane Sy Person ing the LEAP curriculum and re- rial for some other research project lated Arboretum resources to a total unseen by us today. Arboretum has been of 75 Boston teachers and their As we for the next lay plans Theawarded a $37,000 grant from students. quarter century at the Arboretum, the Dwight D. Eisenhower Math we are continually returning to the and Science Education Program for fundamental importance of our col- the teacher training component of First Arboretum lections, including the historic the 1993 LEAP (Learning About Deland Award Olmsted landscape in which they Plants) Teacher Project. Allocated are set. We shall maintain our tradi- through the Massachusetts Higher Davies, a graduate student tional commitment to their excep- Education Coordinating Council, Sat tuart Harvard University, has re- tional care and curation. At the this fundmg will support an ex- ceived the Arnold Arboretum’s Deland Award in of his same time we are actively seeking panded Arboretum commitment to support the of science studies of the new opportunities for the use of improving quality comparative systemat- in ics and of these collections that transcend our education the Boston elementary ecology tropical rainforest schools. In collaboration with the trees. historical mission As was the case Boston Public School Science De- The Deland Award was re- with E. H. Wilson in the early years partment, 25 teachers from twelve cently established from a bequest of of this century, challenging oppor- schools will be selected to partici- F. Stanton Deland, Jr., to support tunities, often in distant, unexplored pate in the 1993 summer research on the biology of woody regions of the world, will make the workshop. These teachers will take part in an plants. Mr. Davies, the first recipi- Arboretum an international leader intensive of horticul- ent of the award, will combine on- in botanical research and education. study botany, ture, and ecology that emphasizes going field studies in Malaysia with the basic plant science concepts and research in the Harvard University hands-on learning strategies that Herbaria in Cambridge. Completion of the ; Lilac Renovation =

Peter Del Tredia c the planting of eighty BV/* new ltn accessions, the restora-

tion of the lilac area, which was started over five years ago, has been completed. Most notable among the new additions are forty large speci-

mens that were moved in from the

Case Estates with the generous assis- tance of labor and equipment by Ollie Capizzi of Capizzi and Com- pany of Acton, Massachusetts. The Arnold Arboretum has been awarded the Boston’1: 1992 Best Working with Tony Capizzi City of Auardfor Kept Neighbor in the Open Space category. The people responsible for keeping the Arboretum are, and a mechanical tree spade, Jim to rou : Bruit Munch, Pat Bob Nickerson and Bruce Munch of the from left right, top Wdlougbby, Farmgliett/.Jim Nickenon, Mike Gormley, Luis Colon, Julie Coop, Karl Homes; bottom rou: Dave Arboretum grounds crew dug the Moran, Jim Papargins. Mark Walkama. Dennis Hams. Maurice Sheehan. and Don forty plants over a three-day period Gatnck Kenny Clarke is missing from the picture. and moved them into Jamaica Plain on a flatbed truck All were planted been of in their permanent locations within studying patterns regeneration in a variety of woody plants, including a week of being dug, no small task Kalmia. Castama. and Sequoia given that many of the plants weighed close to a thousand pounds. A new bed containing seven cultivars recently introduced by the late Father John Fiala of Medina, Ohio, has also been established. All of the introductions selected for the display have spectacular flowers and With this issue Peter Del Tredici appear to be fairly mildew resistant. leaves the editorship of Arnoldta and To round out the renovation, turns his full attention to the Living lilac accessions from the Dana thirty Collections He was Assis- appointed Karen Madsen has been appointed Greenhouse nursery were planted tant Director for the Collec- Living Editor of Arnoldia. She brings long the lilac area In all, over tions this past summer. Peter has throughout experience m editing both books and been associated with Harvard Uni- one hundred plants were added to periodicals and is an instructor in versity for 20 years, first at Harvard the collection, all within the space the Graduate Program in Landscape Forest in Petersham as a researcher, and of the Radcliffe of six weeks, a remarkable feat con- Design History then as Assistant Plant Propagator of College Seminars A past contributor that the Arboretum was sidering the Arnold Arboretum He was to Arnoldia. Karen has participated packing up and moving during the awarded the PhD in biology by Bos- in many of the courses and tours of ton in 1991 for in same time period. A hearty con- University study the Arboretum She will welcome the evolution and natural history of gratulations to everyone who your opinions and ideas as she begins Gingko btloba. Recently Peter has worked so hard. work on the next issue

3 Botany Courses at these are invariably some of the botany for students new to the disci- the Arboretum most popular courses offered in the pline, this course also serves as a re- Arboretum’s adult education pro- fresher for those who feel the need to Marcia Mitchell gram. For those who find that their brush up on old skills. Among the curiosity is whetted by the display topics to be explored are plant cells bot’a’ny n. The division of biology around them, the Arboretum’s and tissues, cell division, plant that treats of plants with reference to botany courses will introduce the anatomy and morphology, plant di- their structure, functions, classifica- careful observer to new worlds of versity, evolution, and ecology. tion, etc. plant appreciation and enjoyment. BOT 228 The Conifers people first encounter A Selection Manythe Arnold Arboretum’s Liv- of Botany Offerings The conifers, or cone-bearing plants, are a of the New ing Collections on a casual stroll BOT 131 Flora of New England: major component We will discuss through the grounds. On subse- A Comprehensive Survey England landscape. conifers and as become familiar the natural history of quent visits, they This course provides an opportunity learn how to the native with the geography of the Arbor- for the experienced plant enthusiast recognize will see etum’s come to see genera and species. Students 265 acres, they to gain a comprehensive knowledge the of structures and what traits distinguish one conifer diversity plant of our native New England flora. from another, how conifers the variations in form and texture. Participants will learn the region’s species and are such Some visitors remain inter- reproduce, why conifers quietly major vascular plant families, in- content to special plants. ested observers, pursue cluding characteristic species and private thoughts or conversations as habitats. they walk the Arboretum’s roads. Please call the Education Department, 524-1 718, to request a course catalogue For other visitors, however, the BOT 100 Introduction to Botany initial contact with the Arboretum’s or to register for Arnold Arboretum Designed as an introduction to vast collection of woody plants is the beginning of a lifelong exploration. It is for these visitors that the Arbo- retum has long offered adult educa- tion courses in botany, as well as many courses in horticulture. Through these courses, most designed to cover the planned mate- rial in six course sessions or fewer, adult students can gain a greater ap- preciation of the links between spe- cies of woody plants, and an under- standing of the systems of classifica- tion by which plants are described. Some of the Arboretum’s botany courses are designed solely as class- room learning: many of these take place during the cold winter months. Others are planned around study of specimen trees and shrubs Lilacs, recently moved tn from the Case Estates, had to be planted with a backhoe. on the Arboretum’s grounds, and

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