LEAVES
A PUBLICATION OF THE HOLDEN ARBORETUM
Fall
2015 Fall 2015
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leaves Fall 2015
Cait Anastis, editor editor@holdenarb.org Jackie Klisuric, art director
administration Clement W. Hamilton President and CEO Natalie Ronayne Executive Vice President Jim Ansberry Director of Finance David Burke Research Department Chairman Roger Gettig Director of Horticulture and Conservation Brian Parsons Director of Planning and Special Projects Marie Monago Vice President of Advancement Paul C. Spector Director of Education and Public Programs Nancy Spelman Director of Human Resources and Safety
board of directors
contents JACKIE KLISURIC
features
departments
4 6 8 9
10 Plant Profile 12 Plant This, Not That 14 Ask Charles
Gaining New Perspectives Canopy Walk, Emergent Tower Open
Microbes In The Soil
Just a part of the dirt or unseen heroes?
CBG’s Vacant to Vibrant
Vacant Plots into Community Gardens
Cladrastis kentukea (American yellowwood)
Paul R. Abbey, Chairman Victoria Broer, Vice Chairperson William Conway, Vice Chairman Jonathan E. Dick, Vice Chairman Robert R. Galloway, Secretary Sarah L. Gries, Vice Chairperson Peter S. Hellman, Vice Chairman Stephen J. Knerly, Vice Chairman Joseph J. Mahovlic, Vice Chairman C. W. Eliot Paine, Vice Chairman Constance Norweb Abbey Thomas D. Anderson Anne Barnes Barbara Brown Christopher A. Cullis Paul E. DiCorleto Ruth Eppig Lydia Harrington
Viburnum plicatum f. tomentosum
directors emeriti
Ralph W. Abelt Jeanette Grasselli Brown Miriam N. Gale Henry R. Hatch Arlene M. Holden
Volunteering
Corporate Group Volunteer Opportunities
On the Cover: The Kalberer Family Emergent Tower.
Ellen W. Jones Nordell Michael Marino Cynthia Moore-Hardy Robin D. Schachat Lynn C. Shiverick K.K. Sullivan Timothy L. Swanson
T. Dixon Long Henry L. Meyer III William J. O’Neill Jr. John Sherwin Jr. Penelope Theis
honorary directors Mary Groves Alison C. Jones
Thomas W. Seabright Helen M. Whitehouse
Volume 13, Number 4 ©The Holden Arboretum Leaves (ISSN 0518-2662) is a class and events magazine published quarterly by The Holden Arboretum for $10 per year for members (included in membership fee) and $55 per year for nonmembers
Leaves
Periodicals postage paid at Mentor, Ohio
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JACKIE KLISURIC
Postmaster: Please send address changes to Leaves: The Holden Arboretum, 9500 Sperry Road, Kirtland, Ohio 44094-5172
JACKIE KLISURIC
from the president I hate to be a Johnny-one-note, quarter after quarter, but I sure hope you are excited as I am by the impending opening of our new Canopy Walk and Emergent Tower. Already, as I write this column in June, the intrepid souls who have “piloted” the tower climb have expressed the universal and gratifying “Wow”. Lest we forget, as we make our final kick to the end of New Leaf Phase One, there are other new projects to celebrate. Today I am writing in the dark – a state in which I often am accused of being anyway – because our electricity is out to accommodate the construction of road crossings for the five-mile deer fence that will protect the plant collections and gardens in our core 230 acres. What a difference that will make, obviating all those individual protective fences we have installed every winter. And the end is in sight for the restoration – truly an ecological resurrection – of Corning Lake, augmented by the picturesque new Streamside Meadow Garden and a restored Lotus Pond just downstream.
In last quarter’s column I suggested that we won’t rest on our laurels. On second thought, maybe just a little bit – as we appreciate what we have accomplished together. As always, thank you for your partnership and for your commitment to our region’s trees, forests and communities – and even our non-woody plants!
Clement W. Hamilton, PhD President and CEO Fall 2015
Many of you are birders, and I know you have shared our desire that the lake return to its former health. Holden friend and birder extraordinaire Haans Petruschke predicts that migratory waterfowl, which were so diverse and numerous in years past, will rediscover Corning Lake very soon after its ecological balance and productivity are restored – who says you can’t go home again?
On the organizational front, the Arboretum/Botanical Garden integration continues to progress, and welcome again to Garden members as we share information about both campuses’ wonderful plant displays and programs. I do hope everyone experienced the Botanical Garden’s tree houses this summer, which lent a fun new perspectives to the gardens and woods. I hear great things from members who have begun engaging with the “other” campus’s programs, presented side-by-side in our combined Classes and Events schedule.
JACKIE KLISURIC
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Gaining New Perspectives
Tree Canopy by Cait Anastis, editor
Traversing the bridges of the Judith and Maynard H. Murch IV Canopy Walk or climbing to the top of the Kalberer Family Emergent Tower, most signs of human impact on the forest disappear from sight leaving only the beauty of the trees and creating a rare and even humbling sensation. This fall, Arboretum visitors will experience the views from these structures and gain a new perspective on the forest as the Murch Canopy Walk, including the Kalberer Tower, opens to the public in September. Accessible from the Helen S. Layer Rhododendron Garden, the Canopy Walk consists of a series of four platforms and connecting suspension bridges that will allow visitors to travel 65 feet above the forest floor and explore the forest canopy. The 202 steps of the Kalberer Tower will allow guests to climb well above that canopy to view the landscape of the Arboretum and the surrounding region, including a breathtaking view of Lake Erie from 120 feet up. “The first thing our guests will experience is the “Wow,” said Clem Hamilton, the Arboretum’s president and CEO. “In addition to that new experience, we hope that guests will gain a deeper understanding of how important our forests are to air and water quality and the livability of the region,” Hamilton said. He also hopes they will develop a greater understanding of the impacts, both positive and negative, that human activities have on our forests, both the negative – including the importation of exotic invasive organisms, the fragmented land clearing, acid rain and climate change – and the positive, ranging from reforestation efforts to aggressive control of harmful invasive diseases and organisms. “How better to engage our guests than to put them right there, in and above the forest canopy?” he said. “So much more effective than words.” Both structures were constructed by Phoenix Experiential Design with education in mind. Robbie Oates, the company’s director of international operations, said he hopes that the canopy walk and tower will help Holden’s visitors gain a greater appreciation for the canopy ecosystem. Traveling into the canopy and then climbing above it will help them look at a forest from a new angle, Oates said. “When we change our perspective, we open up neural pathways that allow us to learn,” he said. “Just changing your perspective and looking down on the canopy, rather than up, will open up those pathways.”
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The goal is to take people “out of their comfort zone, but not into their panic zone,” said Oates, so that learning can happen. To help with that learning process, programming and interpretational signage is being developed, allowing guests to understand what they are seeing and to develop a greater appreciation for our native forests, said Marian Williams, acting director of education.
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“The easiest way to think about it is that the canopy walk is going to give the visitor an intimate experience with the local forest ecosystem and how it works,” she said. “The interpretation is going to focus on what makes up a healthy, diverse forest, showing people the importance of healthy
forests and what that healthy forest ecosystem does for us. “The emergent tower has two stories to tell,” she said. “Part of it is based on the structure itself – because it’s a tall vertical structure, it’s a good way to help people understand how the physiological processes work within a tree through its trunk, its roots and its leaves. You can’t really care for a forest unless you understand how that individual tree works.” At the top, the interpretation will shift away from the inner workings of the tree to look at the big picture. “People will want to know where they are and what they are seeing, so there will be information up there to give them a sense of place,” Williams said. “On top of that, it will convey the idea of how we are part of the forested landscape system that we work in, play in and manipulate as humans.” Climbing above the canopy will give visitors a different view of those forests. “When all the leaves are out on the trees, you really get a sense of the texture of the forest,” Williams said. “It’s almost like a very gently rolling sea. It’s not flat, it’s sort of undulating, and that in itself, can tell a very interesting story. The canopy top affects the movement of air masses and assists with the mixture of atmospheric gases.” Visitors will play a role in developing how those educational messages are delivered. When the structures open in September, the only signage will be orientation signs, getting people ready for the experience. Additional signage will be tested later before the final interpretive messages are put in place. “We’re working as a team to develop interpretation, but we need to get mock-ups out there and test it on people, ideally at the site, to see if they are getting the messages we wish to share,” Williams said. “We have to see how people use the canopy walk and tower – and in addition to what we want people to learn, we need to see what they want to learn. We want to live with the situation for a year, to see how best to talk about it.” The structures took more than a year to complete. Parts were manufactured off site using southern yellow pine, which is sustainably farmed, before being assembled at the Arboretum. The project presented the construction crews with a few challenges as they worked to build the new structures while keeping the disruption of surrounding forest to a minimum. To accomplish this, last fall a helicopter was used to airlift segments of the tower into place after they were assembled in the overflow parking area at the Corning Visitor Center. The $1.3 million dollar project, part of the New Leaf Capital Plan, was inspired by The Holden Arboretum’s mission to conserve native forests, Hamilton said. “The Canopy Walk answered the question, ‘how can one of the nation’s great arboretums contribute to forest conservation in a unique and appropriate way?’ ” Projects for the New Leaf Plan, which also includes the Eliot and Linda Paine Rhododendron Discovery Garden, the R. Henry Norweb Jr. Tree Allée, the ecological restoration of Corning Lake, new deer fence around the core gardens and collections,
and improvements to the Warren H. Corning Library and our irrigation system, would not be possible without community support. More than 500 donors contributed close to $9 million dollars to fund these projects during the New Leaf Capital Campaign, exceeding the campaign’s original goal of $7.85 million, set in October 2012. Support for New Leaf was so strong that the Arboretum reached its initial goal before launching the public phase of the campaign in the fall of 2013; our extra success enabled additional projects to be “elevated” to Phase One, Hamilton said. One of the things Alan Frye, Phoenix’s director of operations, hopes the tower will do is help people experience something unexpected. The first time he went up the tower, as he was just below the top, he had the new experience of looking at a tree and only seeing the smallest of its branches. On the ground, you see tiny branches, he said, but the larger branches and trunks are also always present. And once you reach the top, there is the view from above the canopy to appreciate. “It’s wonderful to watch the look on people’s faces when they reach the top for the first time,” Frye said, adding that for many people completing the 202-step climb will be a reason to get excited. “You’re going to be hearing that a lot – ‘I can’t believe I made it to the top.’ ” Hamilton is confident we will also be hearing “And I am glad I did.”
“How better to engage our guests than to put them right there, in and above the forest canopy? So much more effective than words.” Clem Hamilton
Fall 2015
PHOTOS BY BRIAN PARSONS
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Microbes in soil: Just a part of the dirt or
unseen heroes? by Sarah Kyker, Stephen Krebs and David Burke, Arboretum scientists Have you ever eaten yogurt to improve your digestion? It’s been commonly known for some time that certain types of microbes, both bacteria and fungi, can affect our health in positive ways. So, we are told to eat yogurt for better health. It’s a simple recipe for healthy living, but only part of the story. The fact is, our bodies and those of most other animals and plants, both inside and out, are covered by microorganisms. None of us go through this world alone – and we shouldn’t want to – because microbes are essentially important to us. For example, the bacteria in our intestine help us absorb nutrients from our food and synthesize vitamins B and K, while bacteria all over our bodies may protect us from disease-causing organisms. Scientists have come to call this collection of microbes that live on other organisms by a new name; microbiome.
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The microbiome is a very hot topic in biology right now referring to the group of microorganisms, including their genes and genomes, which live on or within another host organism. Microbiomes are being studied at a rapid rate in animals, plants and, especially, humans for their protective effects against disease. Disruption of the microbes in the human intestine, for example, has been linked to higher infection rates by Clostridium difficile – more commonly known as C. diff – a really bad intestinal infection that can lead to inflammation, sepsis and even death. But, the good news in the fight against C. diff is that a healthy intestinal microbiome is proving, thus far, to be a cure.
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But what about disruptions to natural systems like forests? Can disruptions alter the microbiome of forest trees? It is well accepted that certain human activities have a negative impact on forest health and the negative effects can be direct or indirect. For example, when acid rain falls over a forest, it can directly harm trees and other understory plants by creating leaf lesions. But, acid rain can also negatively impact forest plants indirectly by lowering soil pH. Holden scientists have been studying this indirect effect of acid rain on soil since 2010, and we have been finding that acidic soil conditions change the taxonomic makeup of fungi and bacteria – two key organisms in soil – compared to soils with more neutral pH. What does a change like this, to seemingly small components of the ecosystem, mean for forest health? Our research to date has shown that changes to microbes associated with acid rain can affect nutrient cycling in forest soil. But there is also growing evidence within the scientific
community that these small, mostly unseen organisms can also help protect plants from disease! For plants, the idea of microbial root inhabitants being important to health was first suggested in 1904 by Lorenz Hiltner, who also defined the term “rhizosphere” – the zone of soil around plant roots that interacts directly with the plant. Since then, scientists have been discovering disease-suppressive microbes, for example the bacterium Pseudomonas aeruginosa as well as bacterial and fungal-derived antibiotic and anti-fungal compounds which help protect plants against disease. But, the research on entire plant microbiomes is really in its infancy and mostly being done for agricultural crops. Here at Holden, though, we are wondering if the taxonomic changes we see for bacteria and fungi in forest soil in response to soil pH changes are associated with higher or lower disease incidence for the trees. In other words, can acid rain disrupt the protective effects of the microbiome of forest trees? A recent greenhouse experiment conducted by Holden scientists David Burke, Steve Krebs and Sarah Kyker, along with the help of Holden volunteer, Glenn Novotny, investigated the microbiome of the forest tree Fagus grandifolia (American beech) and how it may protect the beech trees against a foreign pathogen. For this study, juvenile beech trees were transplanted into previously pasteurized soil, which had been steam heated to kill any organisms. The roots of the beech trees were then exposed to different microbiomes by inoculating the pots with field soil from research plots in the forests of Holden’s Pierson Creek Valley. The research plots were either at ambient soil pH (approximately 4) or had received limestone to raise pH levels (approximately 6) and contained a very different taxonomic make-up of bacteria and fungi. Some of the beech pots did not receive forest soil and served as controls in the experiment. After allowing the microbiomes within the pots to establish, the fungus-like organism Phytophthora cinnamomi was added to the soil of half of the pots. P. cinnamomi is a globally invasive plant pathogen that causes root rot disease on more than, 1000 plant species. One interesting component to our greenhouse study is that P. cinnamomi does not occur naturally in Northeast Ohio forest soils; thus, the microbes in the beech pots had been neither previously exposed to the pathogen nor had they evolved any
Many forest soil fungi produce mushrooms and colonize tree roots helping to protect the trees from diseases. defenses against it. Further, if the beech trees showed resistance to P. cinnamomi, we could attribute that to their newly acquired microbiome from the forest soil because there is unlikely to be any host (beech) resistance to this invasive pathogen. (It is important to point out that even though P. cinnamomi has not naturalized in Northeast Ohio’s forests, it is present across altered landscapes of our area, such as in nurseries, parks and home gardens, where plant material has been shipped from areas where P. cinnamomi naturally occurs; thus, our experiment where beech trees are growing in a nursery setting is not releasing an invasive pathogen into Holden’s forests.) The only thing to do once the beech trees were challenged with P. cinnamomi was to wait and see what symptoms, if any, developed. We found that P. cinnamomi did have a direct effect on the beech trees – a reduction in root biomass seven months following inoculation with this pathogen. This result was not too surprising given that the pathogen causes root rot disease. Interestingly, 19 months following the P. cinnamomi inoculation, when we surveyed root biomass again, root biomass was mostly similar between the beech trees that were challenged with P. cinnamomi and the trees that were not. However, this was not the case for the control pots in our experiment, which contained only pasteurized soil and no forest soil, as a reduction in root biomass was still observed for the trees challenged by the pathogen. We also found that P. cinnamomi disrupted the bacterial and fungal communities that made up the beech microbiomes and changed the taxonomic make-up of the bacteria and fungi in pots that received soil from the field plots. But the largest change in the bacterial and fungal composition was, again, in the control, pasteurized soil only pots. Even though these pots had pasteurized soil to begin with, because the beech trees were kept outside, a microbiome did develop as bacteria and fungi blew into the pots. But, our data thus far are suggesting that this microbiome that developed slowly within the pots offered less protection against a foreign pathogen than microorganisms from forest soil.
Many herbaceous plants like Trillium have mycorrhizal fungi within their roots that help the plant acquire nutrients from soil. These roots have been stained and examined with a high power microscope so the fungi within the roots can be seen.
Research scientists at Holden collecting soil and tree roots near the forests of Pierson Creek Valley.
Fall 2015
This experiment did not demonstrate conclusively that raising the pH of acidified forest soils could result in soil microbial communities capable of increasing tree disease resistance. However, the results showed that regardless of the pH of the forest soil, the microbiomes that developed from the forest soil offered protection
against a root disease that was not seen in their absence. It’s possible that in both forests affected by acid rain and those that are not, the soil microorganisms act as a line of defense against soil-borne pathogens and really are unseen heroes for the forest trees. Who would have thought that yogurt and soil have so much in common and that the tiny microorganisms they contain would be so important to the larger hosts that depend on them so much?
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partnerships Transforming Vacant Plots into
Community Gardens by Vicki McDonald, communications director
CBG scientist Sandra Albro and John Hopkins from Buckeye Shaker Square Development Corporation. The Botanical Garden, in collaboration with Buckeye Shaker Square Development Corporation, recently completed work on a green infrastructure project that converted three vacant land plots, into community gardens. The stormwater gardens/community recreation spaces are part of Vacant to Vibrant, a 3-city project that will transform small vacant lots into community assets. The renovated lots will collect runoff to help alleviate combined sewer overflow while also bringing recreational space to neighborhoods that need it. Vacant to Vibrant is a Great Lakes Protection Fund–supported initiative which aims to stabilize neighborhoods that have been in decline. The project received $861,000 to be used over a four year period toward development, upkeep, research and reporting. $18,000 has been designated to build each of the nine plots.
In May, the Botanical Garden hosted a public opening for three green spaces in Cleveland’s Woodland Hills neighborhood.
Through this project, Cleveland Botanical Garden and Great Lakes Protection Fund hope to advance knowledge on sustainable development practices and become leaders in urban revival strategies that can be replicated in areas across the Great Lakes region. Cleveland Botanical Garden and Vacant to Vibrant community partners identified areas in Buffalo, Cleveland and Gary with similar characteristics; all three neighborhoods are in close proximity to the Great Lakes and within urban areas that have suffered great decline in recent decades. The areas selected also face similar physical challenges including a high incidence of derelict properties, high commercial and residential land vacancies and aging and deteriorating sewer/stormwater infrastructure. Cleveland, Ohio
Local partners, community representatives and residents were in attendance for a ribbon cutting, reception and tours of the spaces.
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The first three Vacant to Vibrant sites to open are located in the Woodland Hills Neighborhood on Cleveland’s east side. This area was originally developed during the late 1800s. In the decades between 1900 and 1930, Woodland Hills (which became part of Cleveland in 1913) was heavily settled—largely by Hungarian immigrants. It is predominantly a residential neighborhood with many two-family structures and sits on the hillside that overlooks the rail lines and industrial development that occurred at its base to the west. The Vacant to Vibrant sites were built by LANDstudio in collaboration with Buckeye Shaker Square Development Corporation who, together with Cleveland Botanical Garden, worked closely with residents and community leaders to develop the sites.
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continued on page 15
V2V creates recreational green spaces on vacant parcels in urban neighborhoods for stormwater management and neighborhood stabilization.
Corporate Group Volunteer Opportunities
volunteering
Blooming at The Holden Arboretum by Robin Ott, volunteer coordinator
Dig In Our Gardens Weekdays & limited Saturday mornings, late April to November Help care for and maintain one of Holden’s gardens. Projects may include such tasks as weeding, branch/acorn removal, raking, mulching and planting. No experience necessary; onsite training and staff support provided. Group size: 5-20 per project Requirements: Volunteers should be able to engage in light to moderate physical activity and work outside for up to three hours.
Protect & Preserve as a Land Steward Weekdays only, late April through October Help to promote biodiversity in Holden’s natural areas by removing invasive, non-native plant species by hand. No experience necessary; on-site training provided. Group size: 8-25 Requirements: Ability to engage in moderate physical activity, including bending and kneeling and work outside for up to three hours. In addition to the satisfaction of accomplishing something together, volunteer groups are provided light refreshments and the opportunity to explore the grounds after their project. Depending on availability, groups also may utilize the Holden Shelter House at a discount to host a meeting or enjoy lunch together.
Interested?
Fall 2015
Contact the Holden volunteer office at 440.602.8003 or rott@holdenarb.org at least three to six weeks in advance with preferred dates and number of volunteers.
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Cladrastis kentukea (yellowwood, American yellowwood) by Ethan Johnson, plant records curator Cladrastis (klad-RAS-tis) kentukea is a very uncommon yet beautiful tree first discovered in the Cumberland region of Tennessee by French botanist André Michaux in 1796. It may still be found growing naturally on limestone bluffs, on slopes, ridges, in river valleys and along streams in Alabama, Mississippi, Missouri, Arkansas, Tennessee and Illinois as well as southern Indiana, eastern Oklahoma, western North Carolina and northern Georgia. Belonging to the Leguminosae (pea family), there are six species of Cladrastis, all native to China and Japan except for Cladrastis kentukea. In late September through mid-October at The Holden Arboretum the foliage of yellowwood turns an attractive shade of yellow. The stalks of the compound leaves (rachis) persist for a while after the leaves drop. New leaves break bud early in spring with the earliest recorded date at the Arboretum being March 29 in 2012. This makes them susceptible to late spring frosts. Although the tree will regrow a full complement of leaves within a few weeks, these events deplete the precious stored starches necessary for reproduction. The white flowers, borne in drooping panicles, are very showy for about a week every two to four years. In the “off” years bloom is either non-existent or sparse in comparison to a “banner” year. Their fragrance is mild during the day but more pervasive at night. The first blooms typically open between the last week of May and the first week of June and last for about two weeks. Two 14-yearold trees grown from seed in Jessamine County, Kentucky, and planted in our Specimen Tree Collection have yet to flower.
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When the tree reaches maturity – about 20 years from seed or two to four years for grafts – the fairly inconspicuous pods containing hard seeds rarely result in seedlings in the garden. After the leaves have started to fall, the thin 3-4” long brown pods open but some are held into winter. The bark of yellowwood resembles American beech, being light gray and relatively smooth. Its common name refers to the yellow color of the heartwood when freshly cut, turning brown when dried. Frost cracks in the thin bark can disfigure the handsome trunk of yellowwood and allow fungal pathogens to enter, so it is advisable to protect the main stem with tree wrap during winter while the tree is young. Improper pruning can also mar the beauty of this tree. Never prune in winter or spring as sap will “bleed” from the cut and congeal in a most unattractive manner. The best time to prune is July, and the smaller the branch or branchlet cut, the better. When branches larger around than one’s wrist are cut, the wound cannot properly compartmentalize, leading to rot or cavities to form in the trunk. The use of tree wound paint is not recommended as it has been demonstrated to provide a moist environment beneath that is conducive for the establishment of fungi.
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At the Arboretum, the growth rate of young (30 year) yellowwood has been a foot to 15 inches a year on the most favorable sites. In the Specimen Tree Collection is a yellowwood originally received as a 10” seedling in 1958 that measured 30’ tall in 1985 and 54’ tall, 56’ wide, 26” trunk diameter in 2014. It has a fissure in its trunk where rot has set in, and is low-branched like most yellowwood. At the David G. Leach Research Station in Madison is a specimen that was 4’ tall when received on July 28, 1986. This yellowwood has grown in a modest opening between black
locust (Robinia pseudoacacia) trees. The soil it is growing in is a sandy loam. In 2006 it measured 29’ tall by 24’ wide, and in 2011 was 40’ x 25’. Cladrastis kentukea ‘Perkin’s Pink’, in the moist soil east of Lotus Pond has new flowers that are blush pink. ‘Perkin’s Pink’ was propagated from a tree growing at the Perkins School for the blind in Watertown, Massachusetts, and distributed to the Arnold Arboretum as well as to Brimfield Nurseries in Connecticut over 50 years ago. Our specimen was planted on May 8, 1997 in a silt loam and has grown to 26’ tall by 27’ wide as of June 2015. Its fall foliage is the same yellow as the species, although in one year, 2007, it did not turn color until November. This phenomenon occurs with other trees as well. For example, a red maple, Acer rubrum ‘October Glory’, turns color a month earlier in the relatively dry soil along the Corning Visitor Center exit drive than does its identical twin growing in the moist soil of the Arborvitae Collection along Sperry Road. The Society of Municipal Arborists (worldwide) selected the yellowwood (Cladastris kentukea) as its Urban Tree of the Year for 2015. This annual selection must be adaptable to harsh growing conditions, be underutilized and have ornamental appeal. Yellowwood does indeed fit all the criteria above, and can grow in high pH (up to 8.2) as well as low pH soils (to 4.5). However, it is not at all adapted to waterlogged or poorly drained soils. The general rule is “the smaller the better” for long-term success when choosing a tree to plant. Yellowwood transplants quite readily in sizes up to 2-inch caliper. Once established, the tree is fairly tolerant of drought. Its deep-rooted nature is accommodating to companion plantings. A weeping form, ‘White Rain’ has also been selected and may be available in coming years.
plant facts Light Full sun to part shade
Mature size 50-60’ tall with an equal but typically greater spread if open-grown
Source Through a landscaper, special order from local garden centers, or mail-order
Soil type Well-drained, somewhat moist, acid to alkaline
Best location USDA Zones 4b-8a Fall 2015
JACKIE KLISURIC
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plant this not that by Cait Anastis, editor
Plant This, Not That features native alternatives to a commonly used landscape plant that has become invasive. The alternatives were chosen because their characteristics – form, flowers, fruit or fall color – are similar to that of the invasive and fulfill the same landscaping need. Plants that are native to Ohio are recommended when possible as native species are generally well-adapted to local climates and provide additional resources for wildlife. In this edition an alternative version of the same species is recommended.
The Invasive Viburnum plicatum f. tomentosum With its double rows of flattened clusters of florets that bloom mid-spring, Viburnum plicatum f. tomentosum. (fertile doublefile viburnum) can be found in many garden landscapes. It was first introduced to the United States from Japan and China as an ornamental landscape plant, and homeowners will still find a variety of cultivars available. While not widespread in the United States, it can be found in parts of New England and the Mid-Atlantic States as well as in Ohio and Michigan. Adaptable to different soil types, it will grow in full sun and partial shade. The plant adds color to the landscape as it flowers in the spring. It also brings color to the landscape in the fall when the plant produces fruit, but that added bit of color can allow the plant to become an invasive intruder in our forests. “It produces nice showy red berries in abundance, which are very attractive to birds,” said Charles Tubesing, the Arboretum’s plant collections curator. The birds eat the berries and then deposit them where they perch, allowing the seeds to spread out of the gardens and into the natural areas. “One of the places that seedlings have sprung up is in Stebbins Gulch.”
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Chad Knisely, the Arboretum’s natural areas manager, said Viburnum plicatum f. tomentosum growing the a garden produces fruit and is spread by birds into area that infiltration of woodlands. Laurrie Sostman the natural areas is most prevalent in the Stebbins Natural Area, north of Stebbins Gulch.
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“It seems to be sporadic and in small clusters,” he said. “Like burning bush, another invasive, we are seeing a large number of seedlings under mature shrubs, especially if there is a bit of
a light gap. I am certain that if doublefile was more prevalent in the landscape industry, it would be more of a problem in the natural area.” Since the plants Flattened clusters of florets on are shade Viburnum plicatum f. tomentosum. Kenpei tolerant, and dense, they fill up the shrub layer of the forest and shade out smaller plants because they cast heavy shade, Tubesing said. Because they are exotic, none of their natural pests and parasites are present to keep them in check. Once the viburnum takes hold in the natural area, it spreads, crowding out native shrubs and shading out smaller woodland plants. The resulting monoculture eliminates diversity in the forest and shrinks the food source for local pollinators that are dependent on native plants. Cultivars that bear quantities of fruit and should be avoided include Viburnum plicatum f. tomentosum ‘Brockhurst’, ‘Fireworks’, ‘Grandiflorum’, ‘Lanarth’, ‘Mariesii’, ‘Pink Beauty’, ‘Rotundifolium’, ‘Shasta’, ‘Shoshoni’, ‘Summer Snowflake’ and ‘St. Keverne’. All of these plants, except for ‘Summer Snowflake’ were part of the Arboretum’s collections until 2009, when they were removed in an effort to keep the plants from invading the natural areas. “We removed all the doublefile types, including the ones at Lantern Court, which had been there for many decades, and the birds had seeded into the woods,” said Ethan Johnson, the Arboretum’s plant records curator. Crews from Holden then cleared as much of the viburnum out of the adjacent Pierson Creek Valley as possible. Although it wasn’t possible to remove every seedling, “at least now they aren’t dominating the understory,” Johnson said.
The Alternative Viburnum plicatum f. plicatum When making our Plant This, Not That recommendations, we try to provide homeowners and landscapers with alternative species suggestions to plant. However, in the case of doublefile viburnum, we suggest selecting a sterile version of the same species, Viburnum plicatum f. plicatum, rather than the fruit bearing Viburnum plicatum f. tomentosum. At The Holden Arboretum, horticulturists used its extensive plant records database to determine which plants were invasive and which were sterile, said Roger Gettig, director of horticulture and conservation. “We used this list to cull our collections of the invasive cultivars while our natural areas crews continue to remove fertile ones from our natural areas.” The plants that Johnson found to produce little to no fruit include the white flowered Viburnum plicatum f. plicatum ‘Leach’s Compact’, ‘Newport’ and ‘Popcorn’. All of these selections are beautiful additions to the home landscape.
Showy bract of Viburnum plicatum f. plicatum. Robert Stewart
“You have this shrub that is broader than it is tall, with layered branches and rows of pom-poms on top,” Tubesing said. “It’s pretty striking in flower.” While the sterile varieties of the plant do not produce an abundance of fruit in the fall, Tubesing said, they often compensate by producing a showier floral display, with a longer blooming period than their fertile counterparts. While it is possible for the sterile version of the species to produce fruit, it will do so at most in small amounts and poses a minimal risk to our forests compared to the fruiting varieties.
Pompom-like clusters of flowers on Viburnum plicatum f. plicatum. Kenpei
Fall 2015
Viburnum plicatum f. plicatum produces an abundance of flowers, but little to no fruit, limiting its ability to invade area forests. Adam R. Wheeler
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ask Charles by Charles Tubesing, chief horticulturist
Q:
A:
I need to replace a couple of trees in my yard. I’ve seen the advertisements that proclaim “Fall Is For Planting.” Is this accurate or just a marketing ploy? For many kinds of trees and shrubs, fall is a great time to plant.
The production of additional stems and leaves has ceased and root growth can proceed. Root growth into the soil will occur while soil temperatures remain above 40º F. In practical terms, this means that planting done by the middle of October or so will allow for some root establishment before winter. Planting in September is even better. Although many woody plants can be planted in the fall with excellent results, over the years nurserymen have observed that a few species often do not do so well if planted in fall. The following is a list of those plants that are more reliably planted in spring:
it. Then, dig a hole just deep enough so that when you set the tree in place, the top of that first root will be visible after you finish planting. If the root flare is buried, the tree will have to struggle to exist. It will not grow at the rate it should, will be subject to a number of problems and will not live the long life that is expected. As you go around your community, keep an eye out for a tree that doesn’t appear healthy and look closely at the base of its stem. If there is no sign of a root flare, then you know the likely cause of its troubles.
Carpinus spp. (hornbeams) Cupressus nootkatensis or Chamaecyparis nootkatensis (Nootka cypress) Koelreuteria paniculata (golden raintree) Liriodendron tulipifera (tuliptree) Magnolia spp. (magnolias) Nyssa sylvatica (black gum) Populus spp. (poplars) Quercus spp (oaks) Zelkova serrata (Japanese zelkova) Thuja plicata (giant arborvietae) So as long as the trees you want to plant are not in this list, fall planting is a good option.
Leaves
While we are on the topic of planting, I would like to let you in on an essential detail that will get your tree off to the best start at providing all of the benefits you expect from it over a long and healthy life. The tip has to do with making sure that the tree is planted at the correct depth. Have you ever looked at the base of a mature, thriving tree in a woodland? If so, you have observed how the roots radiate away from the base of the trunk. This area is called the root flare. In nurseries, the root flare of a tree often becomes buried, whether with soil in the field or with potting soil in a container. This excess soil is often not removed when the tree is dug or before the potted tree is sold. Before planting a tree, look for the uppermost root in the soil ball or container, and remove any soil that is above
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For more tips on planting a tree, watch our video on the Arboretum’s Youtube channel.
Vacant to Vibrant continued from page 8
Gary, Indiana Gary’s project sites are situated within the Aetna neighborhood, founded in 1881 and annexed by the City of Gary in 1928. Aetna was established as a residential community primarily for industrial workers, and its growth and subsequent struggles traced the arc of U.S. Steel, Gary’s largest employer. The proportion of abandoned buildings and vacant parcels is highly variable
throughout the neighborhood. In Gary, V2V is one part of a comprehensive stormwater management and urban revitalization plan that is being undertaken by city government in collaboration with federal agencies. Cleveland Botanical Garden partnered with Indiana University Northwest, the City of Gary and Strong Cities, Strong Communities to develop the Vacant to Vibrant sites.
Buffalo, NY West Buffalo is a vibrant and diverse community. Buffalo’s west side has a sizeable Somalian, Sudanese and Burmese immigrant population. The Botanical Garden is collaborating with PUSH, or People United for Sustainable Housing on
these plots. PUSH has led the way in creating a communitycontrolled Green Development Zone where quality, affordable housing is intertwined with environmental efforts, mostly on vacancies between and around residential properties.
Fall 2015
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periodicals 速
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