Historical Tree Spotlight: A Cork Bark Collaboration

Parent and child style cork bark Japanese black pine. Photo courtesy of the U.S. National Arboretum.

For this iteration of our Historical Tree Spotlight series, we unveil the history and creative process behind a special cork bark Japanese black pine ( Pinus thunbergii ‘Corticosa’), which is truly a rare specimen. It is a variation of the conventional Japanese black pine (P. thunbergii) found in coastal Japan and South Korea. The cork bark variety of black pine has an overly active cork cambium that makes an already rugged barked pine a novel wonder. The tree prefers mild climates and makes for a popular and aesthetically pleasing choice for bonsai enthusiasts.  

You can check out the cork bark bonsai above at the National Bonsai and Penjing Museum. It is in a parent and child style configuration that has been in training since 1980, when two prunnings from another cork bark pine bonsai in the Museum’s collections were grafted to a Japanese black pine rootstock. The trees represent a mature parent tree in the wild that has given rise to a younger succession which has thrived under the larger tree's protection, yet reaches toward the light to become its own presence in the woodland. 

Read more about the Japanese Black Pine here in our Species Spotlight.

The textured bark of the cork bark variety provides an enhanced and unique look to this bonsai classic.

“The overall ruggedness of black pines in general is valued in bonsai culture, but the cork bark has the next level of barking that really makes this rare and prized,” says Museum Curator Michael James.

One of the cork bark Japanese black pines in 1989  after being grafted by Robert Drechler. Photo courtesy of the U.S. National Arboretum.

The origin of this tree begins in 1980 with the Museum's very first Curator, Robert Drechsler, who passed away late last year. Since cork bark black pines are difficult to propagate, Drechsler used his skills as a talented horticulturist to graft a branch of the cork bark variety onto a conventional black pine rootstock. Dreschler placed the graft low on the base of the trunk, as the difference between black pine and cork bark is so dramatic that a high graft will cause an undesirable inverse taper due to the thickness of the corky bark.

The addition of a second tree was performed in 1999 by the Museum’s second Curator, Warren Hill, creating the parent and child, or twin trunk style we see today. A later curator transplanted the bonsai into a round container made by the American ceramicist, Ron Lang.   

“This tree is a good example of the collaborative art that bonsai is,” says James. “The media is a living organism and has a lifespan longer than the average human. It requires multiple people in continuum to care for, shape and form.”

The main tree in 1989 before its current multi tree configuration by Warren Hill. Photo courtesy of the U.S. National Arboretum.

The Cork Bark Black Pine exemplifies a core mission of the U.S. National Arboretum, as it is a rare specimen of plant DNA. The arboretum collects, conserves and distributes plant germplasm, acting as a library of sorts. Their repository of genetic information benefits both the scientific community and the public good. 

James also credits the impact of this flourishing tree to the work and influence of Robert Drechsler.

“Robert Dreschsler said, ‘we can only hope we've left something behind that will live on,’ and I think it's definitely true in his case,” says James.

Drechsler’s grafted cork barks were originally a part of the Museum’s Education Collection. What started as a bonsai experiment and tool of education has become a collaborative artistic expression. The bonsai has been removed from the Education Collection and placed into the more permanent North American Collection.

Historical Tree Spotlight / Donors and Their Trees – Al Nelson and His Coast Live Oak

Some bonsai just command presence. Such is the case for a coast live oak, or Quercus agrifolia, donated by Al Nelson to the collections at the National Bonsai & Penjing Museum. 

Nelson has become an expert in the care and training of coast live oak bonsai. He also has an oak at the Huntington Botanical Gardens in California. 

Nelson was first introduced to bonsai in the late 1970s during his lunch hour one day while working as a salesman. John Naka was giving a demonstration at a California Bonsai Society event, and Nelson was immediately hooked. He already gardened in his spare time, so he bought Naka’s newly published book on bonsai techniques and taught himself. 

“I attended various bonsai shows and took pictures of every single tree on black and white digital film, studied the photos and put them in a book,” Nelson said. 

After getting some feedback on his bonsai, he decided to take a hands-on lesson. Nelson began studying under Harry Hirao in the early 1980s and eventually became Naka’s student – a fantastic partnership that would last about 20 years – and joined his study group Nam Pu Kai. 

Nelson, Naka and Hirao spent many years collecting bonsai and scholar rocks together at Bixby Ranch in Santa Barbara County. There, Nelson fell in love with California oaks, which became his favorite specimen to work with and study. He has since collected hundreds of trees from the region. 

“They’re such magnificent trees to me because they struggle to survive,” he said. “They get blown over and all contorted.” 

The coast live oak at the Museum almost stayed hidden among the other gnarled branches and twisted trunks of Bixby Ranch. On one scouting expedition, Nelson spotted the tree, which was originally about 20 feet high with a beautiful base, but he decided digging it out would be too much work. After hunting around, he passed the tree again and gave in – he dug through rocky, tough soil for almost five hours to pull it from the ground. 

Nelson cut off the tap root, which was one-and-a-half times the tree’s height. He covered its base with wet rags and moss because, he said, the tree thirsts for water without the tap root. 

“The tree won’t get the water it needs, and you don’t want to dry it out,” Nelson said.

 Nelson with the coast live oak in 2005 (left) and 2016 (right)

The oak didn’t have a leaf on it when he brought it home, but a few sprouted after a couple of months, so he drove the tree to Naka’s house to see if it had bonsai potential. 

“John was really impressed,” Nelson said. “He said it was a magnificent tree and that one day it should be in the U.S. National Arboretum in D.C.”

Thirty years later, Naka’s proclamation came true. The oak has been housed in the North American Pavilion since 2016. Nelson has shown this oak at multiple demonstrations and, as the bonsai was 25 inches at the base at one point, Nelson had to lift it on and off tables with a hydraulic pump cart. 

He said one of the most common accolades for his coast live oak is how many “fronts” it has – the oak doesn’t necessarily need to be positioned a certain way to look like an excellent bonsai. Instead of selling his beautiful specimen, Nelson gives his bonsai to mentees or established institutions like the Museum.

“I want my trees to have a good home because it’s not about the money,” he said. “Even my students have their names on copper tags on my trees for when I croak. But I wanted to see this one in the Museum, especially since Naka praised it so long ago.” 

Former Curator Jack Sustic (left) with Nelson and the oak

Over the years Nelson has learned much about coast live oaks, like how they don’t grow well with wiring or that the branches grow down rather than out or up. 

Museum Curator Michael James said staff have been caring for the tree based on Nelson’s recommendations. The bonsai is kept in the Museum’s temperate greenhouse during the winter to simulate its native climate.

The oak receives a high volume of water and Miracid fertilizer, and the tree is almost completely defoliated after a healthy flush grows out in the spring.

“We might leave some leaves in the inner portions in weak areas and at the base of shoots,” James said. “We cut all the elongated shoots off and anything that is too straight or is not going in the direction that we want.”

He added that the haphazard drooping and arching branches seen on wild oaks can look incredible and he is trying to maintain a “billowy” appearance when training the tree. 

Nelson said he is thrilled that his oak at the Museum – his favorite bonsai – is looking strong. 

“I’m so happy it’s getting some nice and tender loving care,” he said.

Historical Tree Spotlight: Quince forest planting

The quince forest planting, photo by Stephen Voss 2021

One alluring aspect of bonsai is the ability to recreate an entire forest from a far away place all in a single pot. In this month’s Historical Tree Spotlight, we draw attention to a planting of Chinese quinces (Pseudocydonia sinensis) at the National Bonsai & Penjing Museum that does just that. 

Former curator Warren Hill began this arrangement in 1975, growing the centermost and now-largest tree from nursery stock to produce quinces – a yellow, apple- or pear-like fruit (pronounced “kwins”) that is usually not eaten raw but is used in desserts or teas. He then collected seeds from the fruit of that parent tree to grow the surrounding trees.  

Hill combined the parent and offspring trees to create the planting in 2002 and donated the arrangement to the Museum in July 2013. 

Museum Curator Michael James said the trees are relatively similar in age, but Hill grew them to different sizes and shapes by paying special attention to his thickening technique.

“It’s really about how much foliage each tree is allowed to have,” James said. “Allowing a tree’s branches to really extend before cutting them off allows the trees to thicken faster, but trimming branches fairly often keeps a tree smaller. 

Now that the forest planting is fairly developed, Museum staff keeps the foliage throughout the forest planting at a similar vigor to balance the leaf size with the trunk sizes and ensure the trees are proportional to each other. 

“Maintaining this difference in height and thickness really drives home the true representation of how trees look in a natural forest environment,” James said. 

He said the deciduous planting requires a lot of sun and a fair amount of water compared to other trees in the collection. The trees in Hill’s planting are some of the first to flower in the spring, and the quinces’ bark changes colors and textures throughout the year. But James said the planting peaks in the summer, when the bark exfoliates.

Warren Hill and the Chinese quince forest planting, photo credit to Walter Pall

“The smooth bark in the winter and early spring is a mixture of grays and tans and different browns, even greens,” he said. “But when that exfoliates and those colors flake off, it gives way to rosy oranges and pinks that look as if someone lit a match inside the heart wood.”

In the fall, if the flowers are pollinated, the trees grow their quinces, which are so large compared to their branches that Museum staff rarely leave more than one fruit on the composition each year. 

First Curator’s Apprentice Sophia Osorio said the planting is protected in the greenhouse during the colder months, so the quinces don’t always have access to pollinators. Museum staff have to manually pollinate trees, taking a soft, bristled brush from flower to flower to transfer the pollen. Osorio said they will pick a few flowers to enlarge throughout the year and eventually grow fruit, but that takes some extra planning. 

“We have to be careful that the branch we allow to flower is in the right place in the composition and will be able to support that fruit, yet not swell too much from developing,” she said.

Osorio added that the branch often has to be supported with wire because a fruit could easily snap a bonsai branch off by the time it matures in fall.

“The fruit draws tons of nutrients up from the roots, through the trunk, through the branch and to itself,” she said. “Due to that immense transfer of water and energy, the branch with the fruit is going to thicken a lot more than the others.”

Photo by Stephen Voss, 2021

Historical Tree Spotlight – Blue Atlas Cedar

The Blue Atlas cedar in 2012, pot designed and produced by Sara Rayner

A “power couple” is defined as a pair of two people who are each independently influential or successful. 

The Blue Atlas cedar (Cedrus atlantica Glauca Group) featured in this month’s Historical Tree Spotlight was gifted to the National Bonsai & Penjing Museum by a power couple well known throughout bonsai and the overarching horticultural circles: Frederic and Ernesta Ballard.

Ernesta Ballard, a well-known horticulturist and women’s rights activist, previously owned a small house plant business. She developed a reputation in the Philadelphia community and was invited to display her work at the renowned Philadelphia Flower Show, put on by the Pennsylvania Horticultural Society (PHS). Ernesta won a top prize for her submission, and she was eventually tapped for PHS’s executive director position.

In her new role, Ernesta revitalized the event, growing it into a more participatory and educational experience and one of the premier flower shows in the country. As the event regained traction and pulled in more money, Ernesta used some funds to engender the Philadelphia Green program, which transformed vacant lots into flower and vegetable gardens.

Simultaneously, she became known as the “godmother of Philly feminism” for campaigning for the Equal Rights Amendment and founding local chapters of groups like the National Organization for Women. Ernesta also wrote two books: Garden In Your House (1958) and The Art of Training Plants (1962). 

LEFT: John Naka produced this sketch when Fred Ballard hired him as a consultant for the tree. The sketch was featured in the Journal of the American Bonsai Society with an article Ballard wrote about how important it is for other people to critique your trees and what it was like to work with Naka. 

RIGHT: The Blue Atlas cedar in 1990

Frederic Ballard fell in love with bonsai through Ernesta’s influence and became so drawn to the art that he served as one of the inaugural National Bonsai Foundation directors and was appointed the second NBF president in 1990. Both Fred and Ernesta were founding members of the American Bonsai Society. 

The Ballards bought the featured Blue Atlas cedar as a little shoot from Monrovia Nurseries in California around 1960. The sprout was meant to be a landscape tree, typical of the species, but with guidance from bonsai master Yuji Yoshimura, the couple trained it into a cascade-style bonsai. Bonsai master John Naka helped the Ballards develop the apex of the cedar. 

Blue Atlas cedars are native to the Atlas mountains in Morocco. Their popular function as  landscape trees means the species is drought and heat tolerant. But Museum Curator Michael James said this cedar becomes thirsty once it is transferred to a pot and paying attention to its water needs is very important. 

“A lot of times with bonsai you can make the wrong assumptions by thinking about where these trees natively grow and applying those conditions to the potted plant,” James said. “But it doesn’t work that way when roots are constricted in a container. It needs a lot of water.”

The volume of water a cedar demands will depend on the humidity and temperatures of its growing conditions, but James said Museum staff working in Washington, D.C.’s climate frequently water the Ballard’s Blue Atlas cedar twice a day in the summer.

He added that resisting the temptation to cut back the cedar’s shoots too early and letting the tree elongate as it grows throughout the spring allows the tree to build energy. James said trees like the Blue Atlas cedar can even benefit from a lack of clipping long into dormancy. 

“This cedar is a vigorous grower, so those new shoots in the spring will quickly grow out of the tree’s silhouette,” he said. “But it’s good for its health to resist clipping and let the roots build strength through the increased foliage.” 

This cedar can be found among the Museum’s North American trees. The Ballards took part in the groundbreaking for the John Y. Naka North American Pavilion (pictured above) and christened the collection with their beautiful Blue Atlas cedar. Visit the virtual collection here. 

Historical Tree Spotlight: A Black Pine from Dr. Yee-sun Wu

The National Bonsai & Penjing Museum is home to a breathtaking penjing collection housed in the Yee-sun Wu Chinese Pavilion. This month’s Historical Tree Spotlight draws your attention to a Japanese black pine (Pinus thunbergii) from Dr. Yee-sun Wu, whose trees initiated the foundation of the Museum’s Chinese collection and who financially supported the pavilion’s construction. 

A prominent penjing collector, Wu began styling the pine in 1936 and donated it in 1986, along with 23 other trees of various species. Read more about his personal background here. 

This Japanese black pine can be categorized as a tree penjing. “Penjing” refers to scenic landscapes created in trays or ports that often include additions like rocks and ceramic figurines, like a Chinese landscape painting come to life. A pot with a single tree can be called a “tree penjing” but is more commonly known as “penzai,” the Chinese pronunciation of the characters of “bonsai.” 

The pine’s exaggerated primary branch, the lowest and longest branch off the right of the tree, is a distinct Chinese tree penjing quality, James said.

“If your eye follows the curvy line of the trunk up and then down that swooping branch, you can see that it gives a playfulness or a whimsical look to the tree,” he said.  

Many of Wu’s penjing were trained in the Lingnan style – the clip and grow technique – which his father and grandfather are credited with popularizing. James said the dramatic change in the tree’s direction, led by the primary branch, is consistent with the aesthetics of Lingnan style. The sweeping movement emulates Chinese brush paintings and drawings that, along with scholarly pursuits of poetry and culture, have inspired penjing artists for hundreds of years. 

“If you look at a lot of old paintings of trees in China, there are sharp zig zags in the branching with a lot of natural breaks and snaps left in the painting,” he said. “It shows the weathering of the tree and its survival through time.”

This pine inspired the logo used on the cover of a booklet listing the trees Wu gave to the Museum in 1986.

A shot of the pine in its original pot from Wu's second publishing of his book.

Lingnan style technically means “south of the mountains” and strives to reveal but not control the nature of each tree specimen. Because the style encourages spontaneity and whimsy, these penjing appear more natural than bonsai, James said. 

He added that the black pine was likely collected and placed in a pot, like many Lingnan trees, rather than grown from seeds. The original pot is a traditional deep penjing container that fosters strong tree growth, which is useful when trees are first developing. Now that the penjing is more mature, it tolerates the shallowness and size of its current pot, which retains water well and restricts root growth, facilitating shorter branches.

Wu wrote in his book Man Lung Garden Artistic Pot Plants: “The challenge of art in penjing consists of uniting within the same pot the three elements from Chinese proverbs: ‘heaven, earth and man.’”

Caring for the pine

James hesitates to categorize this tree as completely Lingnan because black pines will die if they are constantly clipped back. Evergreens, like black pines, are typically treated with decandling, or the process of removing a first flush of foliage growth to create a second flush of needles shorter than the first. Shorter needles are in better proportion to small trees in containers and increase the trees’ ramification, or number of branch bifurcations, James said.

He added that Museum staff do the bulk of the work on this black pine between June and July, when decandling should be performed. Decandling the pine too early would produce lengthy needles in its second flush of growth, but decandling too late doesn’t give the second growth spurt time to harden before winter.

From August on, James and the Museum team remove old needles with fingers or tweezers. Black pines in the wild retain needles for multiple years, but James said they must remove the older needles periodically to help light filter through the top of the tree to lower foliage.

 “We pull more needles in stronger areas and less in weaker spots,” James said. “This practice makes the black pine look neater and balances the growth.”

Historical Tree Spotlight: The Logo Tree

The Sargent juniper, photographed by Stephen Voss for the National Bonsai Foundation Annual Report in 2019

Have you ever wondered how the National Bonsai & Penjing Museum logo came to be? 

In this month’s Historical Tree Spotlight, you’ll get to know the story behind one of our Sargent junipers, Juniperus chinensis var. sargentii, known as the shimpaku juniper in Japan. While the tree is notable for its place among the first 53 bonsai that established the National Bonsai & Penjing Museum collection in 1976, it’s also the inspiration for the Museum’s logo!

History of the Sargent juniper

The juniper is a yamadori, meaning it was collected from the wild. The tree came from Itoigawa, in Japan’s Niigata prefecture. Donor Kenichi Oguchi, who ran a bonsai nursery known for its beautifully trained junipers in the neighboring city of Okaya, started training the tree in 1905. Oguchi’s employees visited the Museum in 1977 to demonstrate how to use wiring to maintain the shape of the juniper. 

Museum Curator Michael James said bonsai often outgrow or might not match the style of their original containers, but the Sargent juniper has lived in the same antique Chinese pot since it was donated. He said the styling of this juniper is an excellent representation of the natural growth junipers experience in the wild, specifically in the land around Itoigawa, home to some of the most prized juniper yamadori material in Japan. 

Bob Drechsler, the Museum’s first curator, wiring the juniper with two of Kenichi Oguchi’s staff members in 1977

Trees in the Niigata region grow along cliffs and mountainous areas and are exposed to heavy snows and winds. The harsh weather conditions force junipers to fold back on themselves, which is reflected in the way Museum staff have trained this Sargent juniper’s branches to harmonize with the “shari,” or deadwood on the trunk, James said. 

“When training a juniper or bonsai, if you go by the guidelines, the branches often radiate out from the trunk,” he said. “But in nature, their branches fold like ribbons on top of each other. Sargent junipers also have a mounding habit in its foliage that is often cloud like.”

A story of resurrection

In the 1980s and 90s, the Sargent juniper mysteriously started to experience die-back. Finally, a curator determined the cause: a pest called the juniper twig girdler – the larvae of a small moth – had been eating away at the bonsai’s branches each year, slowly killing off parts of the tree until the apex completely died in 1998. 

“In the wild, twig girdlers don't harm junipers too much because the trees only lose a few branches but are perfectly adept and still survive,” James said. “But when it’s a little bonsai, the twig girdler is devastating.”

The larvae bury themselves in tiny holes under the bark, out of reach from treatment like insecticides, he said. Curators tried protecting the tree with measures like screened cages, but the most effective method was using a magnifying glass to find the holes and using a dental pick to scrape out the larvae. 

Left: The juniper in 1998 after losing its apex to the girdlers | Right: The juniper in 2019 with healthy foliage and branches

Once Museum staff discovered how to stave off the girdlers, former Museum Curator and recently retired National Bonsai Foundation Co-President Jack Sustic restyled the tree to create a new apex, and the tree is healthier than ever. 

“Even to this day, that moth returns to this tree annually and often just to this tree” James said. “But when the girdlers are found early enough, with vigilant checking, the branches are not lost.”

The birth of the logo

The Museum’s logo, created for the U.S. National Arboretum and adopted by NBF, came to fruition thanks to a collaborative effort. Former Arboretum Director John Creech initiated the development of the logo to create a “visual identity” for the Museum’s collection, in imitation of Japanese family crests.  

Beverly Hoge in the U.S. Department of Agriculture’s communications department and local graphic designer Ann Masters, who had traveled in Japan, partnered to create the symbol. Masters visited the original Japanese bonsai collection – quarantined in Glenn Dale, Maryland in 1975 before the Museum was built – and was inspired by this Sargent juniper.

The evolution of the NBF and Museum logo.

John Creech noted in his book, The Bonsai Saga, that the logo depicts the Sargent juniper in a double circle to reflect the “sturdiness” of the bonsai and its abundant foliage. The leftmost branch of the juniper breaks the bands of the circle, which symbolizes the “continued vigor of the trees in their new home” – the National Bonsai & Penjing Museum!

“You can see the cloud-like foliage, the twisted trunk, the ribbon-like branches and the line separating dead and live wood in the drawing,” James said. “Those aspects were the main focus when creating the final version of this logo.”

The next time you visit the Museum, be on the lookout for our logo and pass on your knowledge of the significant history of this Sargent juniper bonsai. 

The entrance gate to the National Bonsai & Penjing Museum bearing the logo. Photo credit: USDA

Historical Tree Spotlight: The Mixed Forest

The forest planting as it stands in the Museum today.

Uncertain times provide many reasons to look toward nature for calm and healing. Myriad research has pointed to how natural environments, especially trees, can benefit our health and overall well-being. 

But as this month's Historical Tree Spotlight shows, nature also provides the inarguable fact that diversity is not just important but fundamentally essential to life. This month’s focus is an unorthodox forest planting, often referred to as “The Mixed Forest,” located in the Japanese Pavilion. 

Donated by Nobusuke Kishi, a former prime minister of Japan, this planting has been in training since 1935 and is part of the group of trees that established the National Bonsai & Penjing Museum’s collection in 1976.

The planting consists of various tree species – including hornbeams, Japanese white pines and Japanese beeches – collected as seedlings from Mount Fuji and Mount Ishizuchi in Japan. Museum Curator Michael James said plantings of multiple species are rare because the grower has to incorporate all of the individual care needed for each species, instead of providing the same care to the whole pot. 

But James said mixed plantings are actually a better representation of the natural world – forests aren’t monocultures but complex systems home to copious varieties of plants and organisms.

He added that even though the planting is home to different species, each tree has the same needs: air, water and nutrients. 

“We care for these forests in a way that accommodates the different needs of each species and allow them to all be healthy in the same environment,” James said. 

The planting featured in a 1975 publication.

Helping a Mixed Forest Thrive 

Tending to each tree’s growing requirements is somewhat of a balancing act. James said the pot contains two soil types in separate areas to cater to the different species’ watering needs. 

The middle of the pot, where the pines are planted, is filled with a mixture high in pumice, which helps the soil dry out faster as pines tend to thrive in drier soils. The pines are situated on the top of a small slope, which allows the soil to drain more easily, James said.

But the beeches and hornbeams – deciduous trees – require a bit more water than pines, so the trees are planted in a wetter mixture. James said Museum staff mainly water around the edges of the pot, where the deciduous roots are concentrated, to help control the wet and dry areas.

 Learn more about different soil and fertilization techniques in our Bonsai Basics blog. 

James added that pruning care also differs among species. The white pines are single-flush trees and require branch shortening without losing any candles, or new growths. 

“We also pluck needles to balance the strength of the pines,” James said. 

But the apices and higher branches of deciduous trees have to be pinched and frequently pruned to allow sunlight to filter through to lower branches. 

“They’re all competing for a limited amount of resources like sun, nutrients and water,” James said. “Without that thinning process, the lower branches end up getting weak and less dominant trees will die.”

A picture of the forest planting taken in 1977.

Benefits of Mixed Plantings

James said this planting is exemplary of the many benefits to diversity, both in naturally occurring forests and in human society, as each part of the small ecosystem contains instances of mutualistic relationships.

“This forest has a lot of symbolic meaning right now and is a good metaphor for the importance of diversity not only in plants but in people,” he said. 

 Mycorrhizal fungi, found in the root systems of plants, facilitate plants’ water and nutrient absorption. Plants in return funnel down carbohydrates formed during photosynthesis. 

James said the fungal web also serves as a method of chemical communication between plants, creating a bond throughout plantings or forests. 

“If one plant is attacked by an insect, plants on the other side of a forest through that fungal connection can tell that the plant’s being attacked and can produce chemicals to protect against the attack before the insect gets to it,” he said. 

James added that upper canopy trees also use the mycorrhizal network to provide carbs and nutrients to trees below that are deprived from sunlight and sugars. Additionally, the pines stretch toward the sun, giving needed shade to the deciduous trees – analogous to a natural forest. 

“The different species, fungal organisms and animals all benefit from diversity,” James said. 

Repotting the World-Famous Yamaki Pine

Yamaki Pine at the Museum (Photo courtesy of USDA Agricultural Research Service, US National Arboretum)

National Bonsai & Penjing Museum and U.S. National Arboretum staff have repotted the Yamaki pine, one of the world’s most eminent and symbolically powerful bonsai.

Almost 400 years old, the Japanese white pine has survived generations of travel and travesty, most famously the 1945 bombing of Hiroshima where the tree sat in late bonsai master Masaru Yamaki’s garden. Yamaki donated the pine in 1976 as part of Japan’s bicentennial gift to the American people – the gift that created the Museum.

Museum Curator Michael James alongside former First Curator’s Apprentice Andy Bello worked with Patrick Lynch and Bradley Evans, two Arboretum staff members, to repot the magnificent tree on March 26. James spoke to NBF about the logistics of the repotting.

Last repotted in 2015, the tree’s soil had compacted so much that water had begun to run off the surface of the soil and barely soak in. Sometimes the water might take up to 15 minutes to infiltrate the pine’s root ball, which is a sign that repotting is needed, James said.

The particles of Akadama, or the granular, clay-like type of soil used to plant the Yamaki pine, had compacted from their usual ball-shaped structure to very small, clay-sized fines, blocking water and air from traveling throughout the root ball.

“When the soil gets that dry, it becomes almost like a brick, and then there’s no oxygen in the soil for the roots to breathe and they rot,” James said.

Finding dead roots and compacted soil could derail the repotting plan, raising issues that have to be dealt with on the spot instead of the intended process. 

“It’s hard to do everything you want to do in one repot,” James said. “This one went really well and pretty much as expected. We found healthy roots all around and a really strong mycorrhizal network of beneficial fungal surrounding the roots.” 

Yamaki Pine’s exposed roots (Photo courtesy of USDA Agricultural Research Service, US National Arboretum)

The process

In preparation to remove the pine from its pot, James, Bello and the staff members pushed the tree off of its pedestal and onto a hydraulic lift cart. 

The tree and container weighed somewhere between 200 and 300 pounds, requiring the group to use straps – cushioned with a towel to distribute the pressure point and weight of the pine – to secure the tree to a beam on the roof of the Japanese Pavilion.

The group then carefully cut between the rim of the pot and the edge of the soil ball a few times to release the ball from the pot. Because the Yamaki pine is so large, the group couldn’t simply lift the pine from the pot. They had to lower the hydraulic cart from under the tree and carefully catch the pot as it fell away, freeing the tree, James said.

“The tree looked like it was floating, especially when you’re not looking up to see the strap and the root ball is suspended from the bottom of its trunk,” he said. “It’s a very surreal image because trees don’t float this way and they’re never positioned like this.” 

Tools used during the repotting (Photo courtesy of USDA Agricultural Research Service, US National Arboretum)

James said that, during the winter, the pot had been enclosed in a mulch box, which buffered the pine’s roots from cold temperatures over the past few years, so the bottom and sides of the soil were in good shape. The surface soil, which the mulch did not cover, contained the least healthy roots, so the team used awls, small hooks and brushes to slowly break up that compact area. 

“It's a little bit like art restoration and a little bit like archeology,” James said. “It’s slow, a little tedious and you have to be really careful that you are removing soil and not roots.” 

One challenge the group faced was clearing away old roots that had died without removing healthy new roots or disrupting “essential” symbiotic relationships the tree had formed with other organisms. 

James said mycorrhizal fungi, a white cottony material found among tree roots (see last photo below which shows the white mycorrhizae), feeds off of sugars the pine’s roots created. The pine then benefits from moisture and nutrients the fungus pulls into the roots, so the team had to ensure that some of the fungus remained.

“When you break up that soil, you destroy or hamper that relationship, and it has to regrow,” James said. “The relationship between the roots and the fungus has to remain intact for the pine to stay healthy.” 

He added that no specific date is set for the next repotting, but the process could happen again between the next three to seven years, depending on how the pine recovers from this repotting, how well water drains through the soil and the tree’s overall health. 

“You want to do these repots few and far between on an old tree like this,” James said. 

Yamaki Pine at the Museum (Photo courtesy of USDA Agricultural Research Service, US National Arboretum)

Andy Bello with the Yamaki Pine during the repotting (@bellcraze).

Historical Tree Spotlight: Pasture Juniper

The Juniper as it stands in the National Bonsai & Penjing Museum today. Photo credit: Stephen Voss.

Bonsai are often developed from seedlings or collected from nature. But this month’s Historical Tree Spotlight features a tree with a unique cultivation story.

Jack Douthitt, a prominent Midwestern bonsai master, retrieved this juniper from a cow pasture in South/Central Wisconsin. But before collecting the tree, Douthitt spent time training the juniper in the pasture, preparing it to be dug up so the tree had time to heal and recover from Douthitt’s initial cuts. Museum Curator Michael James said digging up the tree first may have resulted in lost branches and would have prolonged the tree’s recovery.

“Trees in the ground are much more strong and vigorous – they heal quicker,” James said. “Once it’s in a pot, growth is much, much slower. Those preparations he made in the field allowed him to collect the juniper and get it on the fast track to being a bonsai.” 

Douthitt belonged to myriad local, national and international bonsai clubs, including Bonsai Clubs International, American Bonsai Society, Milwaukee Bonsai Society and Minnesota Bonsai Society. The National Bonsai Foundation recognized him in 1987 as “One of America’s Outstanding Bonsai Artists.” 

Douthitt previously studied art and architecture but deviated from that background after discovering the world of bonsai. 

“Once a painting is finished, I lose my emotional involvement with it,” he once said. “In bonsai, the creative process never stops, and the emotional involvement with it never ends.”

Douthitt’s juniper is native to the Midwest and resides in The National Bonsai & Penjing Museum’s North American Collection. The tree retains its small foliage throughout the year and forms both male and female cones as an adult tree. James added that some junipers naturally grow very low to the ground, crawling much wider than they do tall.

The juniper was repotted from its original rectangular pot to a more shallow, oval pot to better complement the tree’s figure. “That round shape of the pot really harmonizes with the trunk’s curves, whereas the old, rectangular edge just didn’t fit with those rounded trunks and branches,” James said.

While the tree technically falls under the evergreen category, James said the juniper’s branches cycle through a few different colors throughout the seasons. In the spring, the juniper sports lime green new buds that contrast against dark green older leaves, but the tree transforms into a deep green in the summer. 

According to James, the juniper turns almost bronze-like when the cold starts to drift in during autumn, and its leaves develop a purplish color when the tree enters a deep dormant state in the middle of winter.

Left: The bonsai in the 80s before it was donated.

Right: The juniper shortly after it was accepted into the North American Collection.

“It’s neat,” he said. “It’s a cute little tree.”

James added that the juniper tends to take well to pinching when new growths sprout in the spring. Once pinched, the tree forms a proliferation of buds and stays quite dense. 

The twisted deadwood that travels up the side of the tree embodies the Japanese concept of “shari.” Douthitt intentionally created the streak of deadwood and multiple jins, or dead branches, to mirror the harsh conditions – like lightning, sun, wind or animal disturbances – that would kill a strip of the bark in the juniper’s natural setting.

“Snowstorms or ice in the wintertime blow up against the side of a trunk, or an animal or something steps on a branch, which is going to rip and tear the bark away, naturally creating those sharis,” James said. “This one was probably done by the collector, but it could very easily have been found that way as well.”

Historical Tree Spotlight: Coast Redwood

The Chambers’ Christmas Card, 1980. The message inside the card reads: “Whether giant or bonsai, the roots of the redwood spread and intertwine to anchor the majestic evidence that God intended, similarly do the roots of Christmas support our faith that man, too, can stand tall. Have a very Merry Christmas, June and Bob Chambers.”

“All I want for Christmas is a bonsai tree” is probably what June Chambers was singing in 1949. She got her wish – and that gift prompted a long life devoted to learning about and caring for bonsai. Chambers developed a beautiful collection, and since then she’s been sending Christmas cards with a different bonsai on the front each year.

One particular Christmas card stands out: the one with a beautiful redwood, or Sequoia sempervirens, on the front. 

Peter Sugawara, a bonsai practitioner who owned Monte Bello Nursery in California, started training this coast redwood from a seedling in 1954. Chambers bought the tree from him in 1972, and Sugawara spent years visiting her yard to help her train the tree. Chambers donated the redwood to our Museum in 1990, and volunteers and curators have been caring for the tree in the North American Pavilion ever since.

“It’s interesting that Sequoia sempervirens is the tallest living thing in the world and the oldest one known of in the Redwood National Park is more than 1,000 years old,” National Bonsai & Pening Museum Curator Michael James said. “It’s likely that this is the smallest redwood that anyone will ever see.”

Caring for the coast redwood

James said the redwood produces shoots with two lateral rows of small needles that can be pinched to ensure the growth doesn’t elongate too much.

Trees in this species develop clustered, vegetative buds at the junction of branches throughout the growing season, he said. If left alone, the clusters will form a whorl, meaning more than two shoots grow from one location. But James said you can prevent that phenomenon from happening on a redwood if you regularly rub off additional buds with a finger or a pair of tweezers, allowing only two shoots or buds to remain at each branch division.

 “If those shoots and vegetative buds are not selected down to only two from every location, then bulbus accumulations of callous cells start to form, which leads to an undesirable inverse taper of the trunk or branches,” James said.