Leaves Magazine Spring 2015 by The Holden Arboretum

LEAVES

A PUBLICATION OF THE HOLDEN ARBORETUM

Spring 2015

leaves Spring 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

contents

Nancy Spelman Director of Human Resources and Safety

board of directors JACKIE KLISURIC

features

departments

4 6

7 Bird Bio 8 Plant Profile 12 Plant This, Not That

The Towering

Tulip Tree

What Holden’s Collections Can Tell Us About Climate Change

10 Holden Completes 11 Volunteers Sought for Stream Restoration Projects New Arbor Care Program

Great Blue Heron

Syringa vulgaris

Aegopodium podagraria (bishop’s goutweed)

14 15 Research News Ask Charles

On the Cover: Spring bud opening on Aesculus glabra (buckeye) east of the Warren H. Corning Visitor Center.

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 Joseph J. Mahovlic, Vice Chairman C. W. Eliot Paine, Vice Chairman Stephen J. Knerly, Vice Chairman Constance Norweb Abbey Thomas D. Anderson Anne Barnes Barbara Brown Christopher A. Cullis Paul E. DiCorleto Ruth Eppig Lydia Harrington

Ellen W. Jones Nordell Michael Marino Cynthia Moore-Hardy Robin D. Schachat Lynn C. Shiverick K.K. Sullivan Timothy L. Swanson Michael T. Victor

directors emeriti Ralph W. Abelt Jeanette Grasselli Brown Miriam N. Gale Henry R. Hatch Arlene M. Holden

T. Dixon Long Henry L Meyer III William J. O’Neill, Jr. John Sherwin Penelope Theis

honorary directors Mary Groves Alison C. Jones

Thomas W. Seabright

Volume 13, Number 2 ©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 Periodicals postage paid at Mentor, Ohio

Leaves

JACKIE KLISURIC

Postmaster: Please send address changes to Leaves: The Holden Arboretum, 9500 Sperry Road, Kirtland, Ohio 44094-5172

from the president Last November I leaped at the opportunity to ascend our new 120-foot tall Kalberer Family Emergent Tower, part of the Murch Canopy Walk project, whose construction was well along at that point. Since handrails etc. weren’t yet installed, we donned harnesses, ropes and clips to ensure our safety; so our journey was a little more adrenaline-generating than what you will experience when it opens to the public this summer. But, among several “eek” moments when I looked straight down, and gazing outward to marvel at the wintry view, I reflected on what the project will mean to the Arboretum. We strive for a guest experience that is both fun and deeply engaging – to the point of transforming one’s world view. Being perched well above the treetops is not only a “wow” moment – especially seeing Lake Erie on the horizon – it also shows clearly the diversity of our forests and how historic land uses have shaped the landscape ecology, dissecting our topography and watersheds. On the way up, I could imagine the different birds and insects we’ll see, offering the opportunity for guests to gain a greater appreciation of the biotic diversity and complexity of the forest! And finally, a thoughtful moment for the future – how might climate change, invasive organisms and exotic new diseases disrupt our forests, and how might we anticipate and ameliorate those disruptions. Fun, for sure, but deep engagement is our truest objective. Another driving objective these days is continued progress integrating the Arboretum and the Cleveland Botanical Garden, whose combination became official this past Sept. 8. I hope you have enjoyed the Botanical Garden this past winter, have taken advantage of reciprocal benefits for your membership and have come to realize how our two organizations truly pull in the same directions and offer complementary guest experiences. You will notice that this issue of Leaves features the first joint calendar of classes and events, opening an exciting world of possibilities with our new partner at University Circle. We would love to hear what you think! Have a wonderful spring, see our rhododendron gardens awaken, watch the restored Corning Lake take shape, and renew your appreciation for the beauty of our trees, gardens and forests. What a time to be part of the Holden family!

CLEM HAMILTON, ROBBIE OATES AND BRIAN PARSONS ASCENDING THE KALBERER FAMILY EMERGENT TOWER.

JACKIE KLISURIC

Spring 2015

Clement W. Hamilton, PhD President and CEO

This summer, The Holden Arboretum will open the Judith and Maynard H. Murch IV Canopy Walk with the Kalberer Family Emergent Tower, providing guests with a new perspective on the Arboretum’s natural areas. As we celebrate the opening of this new landmark, Chad Clink, the Arboretum’s community forester, will be exploring the unique perspective visitors will be gaining with a series of articles on the trees that will be found surrounding the new structure. Rising from the understory, reaching into the canopy, and emerging with a view unprecedented by anything in the region. Layer upon layer of trees and woody plants. As you embark on this journey, consider the importance of these plants in creating healthy sustainable communities.

The Towering

Tulip Tree

by Chadwick Clink, community forester Having many common names, Liriodendron tulipifera (tulip tree) is also known as tulip magnolia, tulip poplar, yellow poplar and whitewood, respectively. We know it best as tulip tree, a very large and fast growing species emerging and towering over the forest. It is no surprise that the best place to take in these venerable specimens is in the woodlands surrounding the Kalberer Family Emergent Tower, which provides an excellent opportunity to reflect on this tree’s historical cultural significance, ecological impact and required care. Historically Liriodendron tulipifera was revered for its gigantic size and related high quantities of wood product. Folklore says loggers were so awestruck and moved to tears by the gargantuan trees that they were rendered unable to harvest them. Accounts of trees reaching 200’ tall were not uncommon prior and leading up to the inception and advancement of the timber industry. Some large tulip trees grow in the forests surrounding the Kalberer Family Emergent Tower installation where students, teachers and general visitors can learn about Ohio’s woodlands from an emergent forest layer.

Leaves

Also presenting themselves and emerging in May to early June are the trees’ namesake flowers; resembling a tulip, these greenyellow tepals with an orange base are attractive. The flowers have the ability to self-pollinate but are also pollinated by flies, beetles and bees. Recognizing the pollination process and other ecological activities ongoing amongst the forest canopy is important; and the emergent tower view will bring us physically closer to these processes. So, as we see pollinators within flowers, we must also be conscientious of sustainable management of trees and forest through production, planting and protection.

Propagation of Liriodendron is relatively straightforward, and the tree can be grown from seed or grafting. As you explore the canopy walk, think about the amount of time required for the trees to have become established and reach their large stature; consider the challenges faced in less hospitable environments because of human intervention. Planting and PHOENIX EXPERIENTIAL VIEW FROM TOWER

PHOENIX EXPERIENTIAL TOWER CONSTRUCTION

protection are important to emulate the natural environment and mitigate potentially negative human impacts. Planting is best balled-and-burlapped in spring to protect the fleshy, fibrous and sensitive root system. Plant trees as they would appear along the canopy walk’s forest floor, with root flare at or slightly above grade and with adequate irrigation – typically 10-15 gallons of water per inch of caliper each week or 1’’ of rainfall per week. To further protect your establishing tree, ensure adequate mulch is provided 2-4 inches thick within the dripline of the tree; the forest floor along the canopy walk has a thick layer of duff rich in organic material and nutrients which insulate and nourish root systems. In the landscape, be sure to keep mulch and soil away from root collar and flares as this can cause decay and girdling roots. Also, consider pruning during late winter to reduce attractiveness to pests and improve compartmentalization of wounds. Last and most salient, site Liriodendron tulipifera in a space where it will succeed – away from structures and with access to large volumes of soil. This tree is not for small residential properties because it is prone to storm damage, and can struggle on streets with small tree lawns. But it is excellent as a specimen plant that can be enjoyed from afar without the potential to conflict with or damage additional infrastructure. While reflecting inside the emergent tower or at your leisure, take the opportunity to consider the ecological significance of our woodlands. Seeing the forest for the trees, or a specific tree, is possible now more than ever. As you emerge above it all, think about the big picture and where to plant a tree or forest of your own. What can we do looking out and into the future of our forests to create healthy, livable and vibrant communities?

Best Management Practices ROOT FLARE AT OR ABOVE GRADE FAILURE TO PLACE ROOT FLARE AT GRADE CAN DAMAGE THE TREE AND CAUSE WOOD DECAY UNCOVERED ROOT COLLAR AND FLARE EXPOSES DAMAGE AND DECAY

Tree Facts Description

Cultural Uses

Deciduous large tree, 90’ tall (max. 200’), spread of 35-50’. One of the largest hardwoods in North America. A single straight stem with outwardly fluid branch habit; upright twigs and branches.

Furniture and wood products (structures)

Range Massachusetts to Wisconsin, south to Florida and Mississippi (USDA Zones 4-9) Moist and well drained slightly acid loam soil, ample above and below ground space, full to partial sun KIWINZ

Larger examples can be found surrounding the Emergent Tower and along the Woodland, Bole Woods and Pierson Creek trails. Smaller examples, with branches low enough to allow visitors to examine the flowers can be found in the Display Garden and near the Holden Shelter House. Spring 2015

Landscape Requirements

Best Locations at Holden

What Holden’s Collections Can Tell Us

About Climate Change by Juliana Medeiros, PhD, Holden scientist

What can we learn about the potential effects of climate change from the plant collections at The Holden Arboretum? The Holden plant records staff has collected data for more than 70 years on the growth and survival of Holden’s accessioned plants, an important prerequisite to maintaining our status as an accredited museum. This plants database, managed using the BG-Base repository, not only reveals some interesting facts about our plant collections (Table 1), it also can be used to study plant growth response to long-term climate trends and extreme events, including record low temperatures or drought, when combined with the daily weather data collected from nearby stations. Using the data to address questions about how plants respond to climate change presented its own challenges. These data were not collected to address questions about how plants respond to climate. For example, with so many plants in our collection, not every plant can be measured in every year. This is necessary given the need to maintain records on thousands of accessions, but the structure of an existing data set can represent a challenge when trying to “repurpose” the data. In addition, the massive size of the plants database presents particular data analysis challenges. Working with Ethan Johnson, Holden’s plant records curator, and Ron Mauk, a Holden volunteer with expertise in ecology and database technology, we first conducted a preliminary study to determine the suitability of the plants database for addressing ecological questions. Specifically, the preliminary study used a subset of about 8,000 records to answer the question: Can we find evidence that plant growth is negatively affected by extremes of temperature and precipitation? To answer this question, we used plant height data collected from 1990 to 2012 to calculate the relative growth rate, or how much each plant grew each year in proportion to its size in the previous year. We compared this to the Palmer Drought Severity Index (PDSI), a measure of extreme climate conditions based on the deviation from long-term average temperature and precipitation. We found a significant effect of PDSI on growth rate, as shown in Figure 1. The top panel depicts the average growth rate, with the variation among different species shown as an error bar for each year. Points within the green region include years with faster than average growth rate, while points within the yellow region are years with slower than average growth rate. The bottom panel depicts the PDSI. Here, the blue region indicates cooler/ wetter years, with the most extreme cold and wet years having the

Figure 1 highest PDSI. The orange region indicates warmer/drier years, with the most extreme drought years having the lowest PDSI. Years in which the spring warm-up was interrupted by a late spring extreme freeze are indicated by the thermometer. Perhaps surprisingly, we found that cooler/wetter years were characterized by slower than average growth rate (e.g. 2004), while even the worst droughts in recent history appear to have had little negative effect on growth rate (e.g. 1999). One hypothesis to explain these results is that soil waterlogging strongly inhibits growth during very wet/ cold years, while the shallow water table characteristic of the Great Lakes Region affords trees access to enough water even in the driest years. Perhaps the most intriguing pattern we saw is that extremely cold temperatures in late spring, after plants have already broken dormancy, have had strong negative effects on plant growth rate. These negative effects have sometimes persisted for several years, such as those seen following events in 2004 and 2005. In fact, this type of damage in continued on page 15

Interesting facts about Holden Arboretum’s plant collections from the Holden Plants Table in BG Base - Table 1 Date range of observations Total number of observations Types of information collected Greatest number of observations by a single person Number of plant families in the collection Longest record for a single plant Largest stem diameter at breast height (DBH)

Leaves

Tallest tree

Largest spread

1937 – 2014 412,246 and counting! Condition, height, canopy spread, diameter at breast height (DBH) 130,761 by Ethan Johnson 162 Pseudotsuga menziesii (Douglas fir) Located between Foster Pond and the Ponderosa Pine grove. Germinated in 1932, planted in 1940, still in fair condition as of 2014. Quercus robur (English oak) Located at Lantern Court along the pea-gravel path east of the entry drive. Last checked in 2012 1.3 m (51.3 in) diameter. Pinus strobus (white pine) Located south of Buttonbush Bog near the loop path adjacent to the emergent tower. Last checked in 2010 — 33.5 m (110 ft) height. Acer saccharinum ‘Pyramidale’ (silver maple) Located in the Specimen Tree Collection. Last checked in 2014 — 23.5 m (77 ft) spread.

bird facts Description Males and females, blue-gray body; yellow bill; black strip over eyes

Size 38.2–53.9 inches; Wingspan: 65.7–79.1 inches

Best location to view at Holden Corning Lake, Heath Pond and Hourglass Pond

Great Blue Heron (Ardea herodias) by Rebecca Thompson, Growing Students in Science program coordinator

PHOTO BY MIKE DOUGHERTY

Great blue herons can be seen in almost every water habitat in Ohio in every season where unfrozen water is present. Their long, specialized necks curl into an S shape for a more aerodynamic flight contour and for a quick strike at prey at a distance. Despite their large size, they weigh only five to six pounds. Great blue herons have specialized powder down feathers on their chest which continually grow and fray, producing fine particles or “feather dust.” They comb these feathers with a fringed claw on their middle toes, applying the powder to their under parts protecting their feathers against the slime and oils of swamps.

year. Males arrive in March and April at the colonies in Ohio and decide on nest spots. Nests are built primarily in trees, but can be in bushes or on the ground. Nests may be reused from year to year or rebuilt every year. Males collect most of the nest materials, passing the materials off to a female in an elaborate courtship display. Females accept the nesting materials and weave a platform cup nest with sticks, lining it with pine needles, moss, reeds and dry grass. Nest building can last from three to fourteen days. Pairs are mostly monogamous during a season, however each year they choose new partners.

Great blue herons hunt alone during the day but can also hunt at night. They have a large number of rod-type photoreceptors in both eyes that help their night vision. Great blue herons are waders, snaring their prey by walking slowly or standing still for long periods of time in the water, waiting for smaller prey such as fish, amphibians, reptiles and insects to come within range of their long necks and blade-like bills. They also forage in wet grasslands and agricultural fields where they stalk frogs and small mammals, such as mice.

Great blue heron females lay two to six pale blue eggs, which both parents incubate for 25-30 days. Both parents feed the young regurgitated food. Fledglings leave the nest around two months old, although they do return to the nest to be fed by the adults for another few weeks.

Spring 2015

Despite being solitary hunters, great blue herons nest in colonies that can number several hundred pairs. Most breeding colonies are located within two to four miles of feeding areas, often in the same isolated area near forested lakes and ponds from year to

According to the North American Breeding Bird Survey, great blue heron numbers are stable and in some areas even increasing. The recovery of beaver populations has created new areas of swamps and meadows suited for great blue heron foraging and nesting. However, great blue heron population decline has occurred in some areas where elevated chemical pollutant levels and reduced water quality are present.

Syringa vulgaris (Common lilac) by Ethan Johnson, plant records curator continued on page 15

Leaves

In the door-yard fronting an old farm-house, near the white-wash palings, Stands the lilac bush, tall-growing, with heart-shaped leaves of rich green, With many a pointed blossom, rising, delicate, with the perfume strong I love. — Walt Whitman,

When Lilacs Last in the Door-yard Bloom’d, 1865

Native to the Balkans in southeastern Europe, Syringa vulgaris (common lilac) is a member of the olive family (Oleaceae), which also includes Fraxinus (ash), Chionanthus (fringe tree), Ligustrum (privet), and Forsythia. Of the 21 species of lilacs in the world, two are native to Europe and the rest to Asia. Among these, the common lilac is the most fragrant and sought after. It has been cherished in gardens and as a cut flower for more than 500 years. In the Display Garden of The Holden Arboretum, there are currently 106 common lilac plants including 87 cultivars. Cultivated varieties of Syringa vulgaris are known and loved for their beauty, fragrance and dependability. Planting of the lilac collection started in 1939 including five common lilacs that still grace the Display Garden. To the northeast of Lotus Pond is an outstanding lilac named Syringa vulgaris ‘Albert F. Holden’ that has fragrant single purple florets with silvery outer edges as they open, making for a dazzling display. Nearby is ‘Atheline Wilbur’ that has fragrant double pale magenta florets. These lilacs were bred and named for the arboretum’s founder and the wife of board member John Wilbur by John Fiala of Medina, Ohio, who authored an excellent book on lilacs.

The Lemoine family of France bred and introduced more than 200 lilacs from the late 19th to early 20th centuries. These, also known as French lilacs, are still among the finest available in commerce. There are 45 Syringa vulgaris cultivars originating from the Lemoine nursery in our collection. Two good examples in the Display Garden are Syringa vulgaris ‘Émile Lemoine’ on the south side, which has fragrant double lilac florets and ‘Cavour’, to the north adjacent to the footbridge, which has fragrant single violet florets. These and other common lilacs bloom for around three weeks at the Arboretum. The flowering time is very temperature dependent, with April 19 being the earliest and May 15 being the latest start of bloom recorded in the past 10 years. Hybrids of common lilac and the early lilac, Syringa oblata of eastern Asia, typically bloom a week to 10 days earlier, with a few flowers opening as early as March 26 in 2012. These hyacinth lilacs, Syringa x hyacinthiflora, are otherwise very similar to common lilacs by all appearances. There are 33 hyacinth lilacs, including 24 cultivars in the Display Garden. Occasionally flowers of both the common and hyacinth lilacs will be damaged by spring frosts as happened during the Easter freeze of 2007. Lilacs can grow quite tall – ‘Miss Ellen Willmott’ was 20 feet in 2014. The average height for our common lilacs that are at least 15 years old is just over 13 feet. The lilacs at the arboretum have been pruned with older stems removed that are less floriferous and likely to become infested with borers. Such pruning rejuvenates older lilacs as most readily grow new stems from their base. Plants not growing well are usually either not getting enough sun, or are in soil that is not well-drained or fertile. Since lilacs prefer a neutral soil pH, incorporating limestone to the planting bed, in addition to composted organic matter, can help plants flourish. Lilacs are very sensitive to herbicides. Even if weeds are sprayed nearby, the “drift” can cause significant damage to prized specimens. I became keenly aware of this in 1981 when the foreman of the Display Garden pointed out to me distorted leaves on lilacs adjacent to weeds I had previously sprayed with

Roundup. Herbicides used to control broad-leaved weeds in lawns can also damage or kill lilacs that have roots in a lawn. Syringa vulgaris ‘Miss Ellen Willmott’ also showcases the variations in fragrance to be found with lilacs, which are often associated with a pleasant scent. The plant has beautiful white flowers, but not fragrance. In addition, the fragrance of the lilac flowers can be stronger or milder on the same plant from year to year. The handsome foliage of lilacs can be marred in the summer by powdery mildew, which can be unsightly but not harmful to the plant. While some cultivars are more resistant to mildew than others, even ‘Dwight D. Eisenhower’ had a slight case of mildew in 2000 when the surrounding trees began to shade it too much, and it was removed in 2013. Seed pods are often borne on common lilacs, but less frequently on the double-flowered varieties. I have not yet noticed any spontaneous seedlings of common lilac in the Display Garden. At my home in Willoughby is Syringa vulgaris ‘Edith Braun’ which was bred by John Rankin of Elyria, Ohio, and named after his fiancée, who died before they were married. ‘Edith Braun’ has wonderfully fragrant single magenta-purple flowers that are also appreciated by my neighbor whose garden shed it is near. Although deer will browse lilacs, it is not their preferred food, at least not at the Arboretum. Good companion plants for lilacs can be found in the Display Garden, including deer-resistant herbaceous peonies and tree peonies. Trees that have flowers complementary to lilacs include Magnolia ‘Yellow Bird’, the dogwood blight resistant Cornus florida ‘Appalachian Spring’, and the red buckeye (Aesculus pavia). Come out to the Arboretum in May and enjoy the lilacs. There will be an opportunity starting this spring for volunteers to participate in a study that ranks lilac fragrance. If you have a good nose for this sort of thing look for notice in an upcoming issue of Holden’s Tree-mail newsletter from Robin Ott, our volunteer coordinator.

plant facts Light Full sun

Mature size 15-20’ tall with a similar spread unless pruned

Source Local garden centers

Soil type Spring 2015

Moist, well-drained, close to neutral ph

Best location USDA Zones (3a) 3b-7b PHOTOS BY JACKIE KLISURIC

Holden Completes

Stream Restoration Projects by Chad Knisely, natural areas manager The Holden Arboretum concluded its second stream restoration project this fall. You may remember reading about The Holden Arboretum’s floodplain restoration project in the Spring 2014 issue of Leaves. The East Branch Chagrin River Stream Restoration Project, as it is formally known, involved the removal of 385 feet of levee, restored 330 feet of the East Branch Chagrin River, and 715 feet of headwater stream. The restoration project also involved the planting of 3.5 acres of floodplain and riparian habitat. Plants chosen for the project included those typically found growing along stream and river corridors such as Platanus occidentalis (American sycamore), Populus deltoides (Eastern cottonwood), Salix (willow) and Cornus (dogwoods). The Conservation Department worked tirelessly to place more than 5,000 plants from live cuttings and potted individuals to complete this project. Many people and organizations were involved in this project. The project was funded by a Section 319(h) Nonpoint Source Program Grant administered by the Ohio Environmental Protection Agency. The Holden Arboretum would like to thank Lake Metroparks for allowing us to collect live cuttings of willow, Eastern cottonwood, and American sycamore for the project from nearby parks. The Conservation Department would also like to thank the Arboretum’s Horticulture staff for providing assistance and expertise, and the Education Department for showcasing the project. The Riverworks team did an excellent job with the design and construction of the final project. The Chagrin River Watershed Partners was instrumental in project management and grant reporting. The completion of this project would not have been possible without the help of all the above organizations and staff. The Arboretum has also been working on a third stream restoration project also funded by an Ohio Environmental Protection Agency Section 319(h) Nonpoint Source Program Grant. The project is located in the core garden area and begins at the outflow of Heath Pond and extends downstream approximately 350 linear feet. The project is referred to as the Pierson Creek Headwater Stream Restoration Project and is viewed as an extension of the natural areas into the core garden area. As such, the project is a blend of natural function and aesthetics.

Leaves

A planting plan has been developed for the stream corridor to include those plants that bloom in June, fitting in with the area’s June Room theme, and at the same time have good stream bank stabilization properties. Shrubs such as Itea virginica (Virginia sweetspire), Sambucus canadensis (American elderberry) and Potentilla fruticosa (shrubby cinquefoil) have been selected for their appearance and tolerance of semi saturated soils. The Riverworks design/build team completed the construction of the project which involved the installation of a dropbox at the outflow of Heath Pond. The development of a stream corridor with the proper gradient, meandering, and floodplain was the main emphasis of the project to maintain a stable stream corridor. The Conservation Department would like to encourage visitors to check out the project.

THE NEW BRIDGE IN THE LAYER RHODODENDRON GARDEN WAS PART OF THE RESTORATION PROJECT

Volunteers Sought for

New Arbor Care Program By Robin Ott, volunteer coordinator

The basis for the Community Forestry program at Holden is rooted in its mission - to promote the beauty and importance of trees to create sustainable communities. As many of our local communities face economic and political challenges to their urban forests, the role that Holden can play in surmounting those challenges is crucial. “Community forestry is any forestry process that intimately involves people,” said Chad Clink, Holden’s community forester. “We understand that urban forests are social-ecological systems, meaning people should and do play significant roles in forest management and land-use decision making processes. Those decisions should be guided and influenced by the community’s desire for sustainable urban forests and facilitated by governance and organizational expertise.” For communities that do not have the resources or experience to successfully manage their own urban forests, Holden would like to facilitate this process by the coalescing of various stakeholders.

volunteering Volunteer Arbor Care Specialist Basic Training Saturday, March 28, 8:30am – 4:30pm OR Wednesdays, March 25, April 1 and April 8 5:30-8pm (Volunteers must attend either the day-long Saturday session or all three evening sessions)

To help this goal become a reality, Holden has created a new volunteer arbor care specialist program. Interested individuals are invited to join a team of volunteers who will be prepared for, and ready to respond to, community requests – especially within their respective neighborhoods or municipalities. Specialists will be trained to provide tree benefit calculations, tree planting, young tree training and basic tree care, including mulching, watering and weeding, as well as outreach and education on the value and importance of trees to a community. Clink said that the purpose of involving volunteers in this work is valuable because it expands advocacy and community based capacity, but also promotes the Arboretum’s vision of growing trees and communities; and what better way to do that than providing people with volunteer tree care opportunities in their respective communities! Volunteers will be required to attend a basic arbor care specialist course, and will need to complete Holden’s general new volunteer requirements – including an application, interview and new volunteer/staff organizational orientation. Additional coursework will be offered in the future for volunteers to expand their skills and earn additional qualifications. Previous experience/education is helpful, but not required. Physical demands vary by project, but generally volunteers should be able to do moderate physical work and be willing to travel to project sites throughout the Greater Cleveland area. Clink expects that volunteers will participate in one or two projects a month during warmer months, maybe less in off-season. Communities and their projects will be chosen based on need, commitment to community forestry and willingness to collaborate with various partners to provide the greatest benefit. This new volunteer role is perfect for those who love trees, want to make Northeast Ohio a little greener and are interested in being active within their neighborhood or community. Benefits to volunteers will include complimentary classes, the ability to connect with like-minded people and opportunities to help protect and revitalize our urban forests. In addition, this new position is flexible to the volunteer’s schedule and will offer projects on evenings and weekends.

To get started, interested individuals should apply online at holdenarb.org or contact the volunteer office at rott@holdenarb.org or 440.602.8003

He who plants a tree, plants hope. - Lucy Larcom

Spring 2015

Want to get involved?

plant this not that

by Eva Rodriguez, education intern

Thousands of plants have been introduced to the United States from other parts of the world. Some have come here accidentally in seed stock, while others were brought here intentionally for horticultural use. A small number of these introduced plants have gotten a little too comfortable in their new environment. Because they have no native predators and produce a lot of fruit and seeds that are efficiently dispersed, they are easily invading natural areas. The aggressiveness of these invasive plants affects natural areas and wildlife by decreasing biodiversity, competing with native and rare plants, and eliminating wildlife habitat and food sources. Plant This, Not That features a list of 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. However, there are many non-native plants on the market that are also non-invasive and possess great ornamental value.

The Invasive

Lonicera japonica ‘Halliana’ (Japanese honeysuckle vine) Lonicera japonica ‘Halliana’ is a readily available cultivar of the infamous and invasive Lonicera japonica (Japanese honeysuckle). L. japonica was introduced into North America in the 1860s from Eastern Asia and Japan. The cultivar ‘Halliana’ was introduced by George Hall to Parsons’ Nursery in Flushing, N.Y., in 1862 as a ground cover species along banks and rough terrain; a single plant can grow to be more than 18 feet in length. Once it escaped into the wild, it became a “most pernicious and dangerous weed” according to E.F. Andrews in a 1919 issue of Torreya, which reported that “it is no uncommon thing to see acres upon acres … buried under the rank growth of this aggressive invader.”

Lonicera japonica flowers.

Leslie J. Mehrnoff, University of Connecticut, bugwood.org

It is not difficult to imagine why L. japonica was brought into North America. This vine is classically beautiful, with deep green summer foliage allowing its fragrant, white trumpet-shaped flowers to stand out when they bloom in early June. As the seasons change, L. japonica’s fall foliage is a brilliant Lonicera japonica fruit and foliage.. bronze surrounded by striking black berries. Many invasive species and Chris Evans, Illinois Wildlife Action Plan, Bugwood.org cultivars lack wildlife value; however, this is not the case for L. japonica. On the contrary, many birds and small mammals consume and disperse the large amounts of fruit this plant produces, according to the U.S. Forest Service. While L. japonica helps provide habitat for birds and small mammals, because of the dispersal of its abundant fruits, this plant can outcompete native plants in woodlands for space and resources. Its vigorous growth behavior can lead to heavy infestations with the plant climbing up whole trees and over structures.

Leaves

L. japonica will grow in almost any soil type and is difficult to eradicate once established in a woodland. Charles Tubesing, The Holden Arboretum’s plant collections curator, recommends that there are many non-invasive alternatives to plant in preference to L. japonica. Birds can disseminate the seeds, so planting it anywhere outdoors near woodlands were it has not already been established leads to problems unless the fruit is removed before they ripen.

Lonicera japonica infestation. Chuck Bargeron, University of Georgia, Bugwood.org

The Alternatives Lonicera sempervirens (Trumpet honeysuckle) Planting Lonicera sempervirens in place of the invasive Lonicera japonica is a far better Lonicera sempervirens flowers. choice for your home landscape and the local ecosystem. L. sempervirens is a woody John D. Byrd, Mississippi State University, Bugwood.org vine native to the southeastern United States. Due to this plant’s native range, it is heat adapted and can easily survive Northeast Ohio’s humid summers. It is also one of the tougher honeysuckle species; in addition to its tolerance of heat, it is deer resistant, and drought tolerant, according to North Creek Nurseries. L. sempervirens has vibrant orange to scarlet trumpet-shaped flowers, which is where it gets its namesake, trumpet honeysuckle. The scentless, flowers bloom from mid-June to August and produce bright red berries in the fall. Both flowers and berries are showy and colorful enough to see from a distance. If you can believe it, there are cultivars of L. sempervirens that have even more brightly colored flowers. “There are so many cultivars now,” Tubesing said. “Some of them we even sell at the Arboretum’s Plant Sale in May.” In addition to L. sempervirens’ horticultural value, this plant has wildlife value as well. The bright red flowers attract hummingbirds and provide them with a sweet nectar meal. With L. sempervirens’ quick growth rate and similar characteristics to L. japonica, this better behaved native honeysuckle will make a practical ground cover in the home landscape, and can be confined to a small trellis or fence rather than running rampant. Examples of this plant can be found in the Paine Rhododendron Discovery Garden, the Display Garden and the Holden Butterfly Garden.

Clematis virginiana (Virgin’s bower) It’s not an easy task to find a native vine as showy and beautiful as the honeysuckles. However, Clematis virginiana’s beauty rivals the beauty of the popular Lonicera species. C. virginiana is a native, perennial vine that is widely available via mail order, and in some garden centers and nurseries. It has scentless, frothy-white flowers on a vigorous, fast-growing vine. C. virginiana’s blooming season is in June and short, lasting a little over a month, but when it does bloom, it does so abundantly and elegantly. The blossoms are followed by fluffy seedheads that are very attractive, adding an additional ornamental quality to the plant. “It’s pretty in flower and pretty in seed,” said Roger Gettig, director of horticulture and conservation. C. virginiana is most commonly confused with C. terniflora (sweet autumn clematis), its invasive Asian relative. An easy way to differentiate the two species is to examine their leaf margins. C. virginiana’s leaf margins are toothed while C. terniflora’s are smooth. Because of its rapid and smothering growth habit, C. virginiana is best planted where it has a fence to climb and cover, and separated from less vigorous plants. Clematis virginiana flowers.

Wendy VanDyk Evans, Bugwood.org

Spring 2015

Clematis virginiana. John D. Byrd, Mississippi State University, Bugwood.org

ask

Charles by Charles Tubesing, chief horticulturist

I visited Holden last October and you were removing the maple trees that grew on the mound in front of the Corning Visitor Center. They turned such a nice red color every fall. Why did you take them out?

STATE STREET MIYABE MAPLE

BRUCE MARLIN

In the fall, Holden replaced the deteriorated wooden benches in the area we call the amphitheater, which included excavating the existing benches and installing a concrete platform for the new benches. This activity provided the opportunity to redo the existing planting, a task we had been eager to perform for a number of reasons. The mound was formed from the material removed from the site of the Corning Visitor Center prior to its construction. Consisting largely of subsoil, the mound had proved a challenging location to grow anything but the most adaptable plants. Red maple is a tree that is tolerant of poor drainage and soil compaction. It can be counted on to grow, even thrive, when planted on typical construction sites without much attention to soil improvement. For this reason, it has been overused in landscapes. At the Arboretum, we advocate planting a diversity of trees. As such, it doesn’t make sense for us to make such a prominent example of a tree that doesn’t justify promotion. There are a number of different trees that we would promote in preference. So, given the opportunity, we removed the trees, which were stressed and structurally unsound, along with the nasty soil and replaced it with sandy loam brought in from Madison, Ohio. The red maples were replaced with a trio of State Street Miyabe maples (Acer miyabei ‘Morton’), a selection of a hardy Japanese species with an upright, oval crown and medium to dark green foliage that turns bright yellow in fall (http:// www.chicagolandgrows.org/trees/miyabemaple.php ). At the other end of the planting was a Katsura tree (Cercidiphyllum japonicum) that was in declining condition that could not be corrected. It was removed, and its prominent position called for a specimen tree with distinctive form to take its place. We selected Green Veil Japanese Zelkova (Zelkova serrata ‘Green Veil’), a tree of upright habit with arching branches that are pendulous at the tips, resulting in a form that is very graceful.

Leaves

In addition to the trees, a few distinctive evergreens were added to provide year-round interest, along with a number of masses of colorful perennials and groundcovers, each of which echoes a planting in an existing garden at Holden. These herbaceous plants are reliable performers selected by our horticulturists, and will provide a changing palette throughout the growing season. They certainly will be much more visually interesting than the rather dour mass of periwinkle that preceded them. When you visit the Arboretum, we hope you will enjoy watching this planting as it changes through the seasons, and the trees as they develop over the years.

GREEN VEIL JAPANESE ZELKOVA

KENPEI

Research News and Highlights Holden Scientist awarded funds to organize international conference on plant water transport. A proposal for a new Conference on Multiscale Plant Vascular Biology submitted by Arboretum Scientist Juliana Medeiros (conference co-chairman) and collaborators William Pockman (conference chairman, University of New Mexico) and Barbara Lachenbruch (conference vice-chair, Oregon State University) has been accepted as a Gordon Research Conference-sponsored meeting. Gordon Research Conferences (GRC) is a non-profit organization dedicated to providing support for international conferences that cover topics on the frontiers of research in the biological, chemical and physical sciences. GRC meetings are small, fewer than 200 people, but they cover very specific subfields of research and so are considered premier conferences for networking and collaboration. Proposals for new conferences are highly competitive, and the GRC Board of Trustees approves only a few new conferences each year. The conference will bring together scientists working at all scales of plant water transport research. The meeting will take place in summer 2016, and pending positive outcomes of the conference in 2016, it may be promoted to an official, bi annual Gordon Research Conference. Advances in plant water transport are of critical importance for understanding how plants may respond to global climate change.

Holden Scientist invited to attend international workshop on plant hydraulics. Holden Scientist Juliana Medeiros was invited to and attended the first International Workshop on Plant Hydraulic Techniques held at the University of Ulm in Germany, Sept. 17-19, 2014. The workshop brought together the world’s leading experts in plant hydraulics, hailing from five continents, in an effort to address current methodological challenges in the field. The outcome of

these proceedings will be a series of Gold Leaf Protocols on the peer-reviewed Prometheus Wiki, a website that offers free access to methods in all aspects of ecological and environmental plant physiology. In addition, the working group will publish an article providing the most up-to-date standards and recommendations for researchers in the field.

Soil pH and phosphorus availability: A long-term study at The Holden Arboretum. In 2009, Arboretum scientists began an experiment to examine the effects of soil acidification on plants and mycorrhizal fungi in hardwood forests of Ohio. To date, more than 45,000 pounds of limestone have been spread on three oak-beech-maple forests in Northeast Ohio, including two forests at The Holden Arboretum (Pierson Creek Valley and Strong Acres). We have found that mycorrhizal fungi respond to changes in soil pH, and alter their activity, suggesting as soil pH increases, phosphorous availability also increases, and forests may be limited by phosphorous under acidic conditions. Surprisingly, our work suggests that more than 3,100 species of soil fungi can be found on the roots of trees within our hardwood forests, indicating that the diversity of soil fungi is higher than we previously expected. Although forest tree growth and nutrient uptake have not responded to our shortterm – less than four years – treatment, mature trees may take a long time to respond to environmental changes and we will continue our study to assess the long-term effects of acidification on forest systems. In addition, this experiment is being used by other researchers from John Carroll University and Case Western Reserve University to explore effects of soil acidification on salamander and insect abundance and diversity. This work will advance our understanding of how human induced acidification of forests effects forest biota and productivity. More information about the NSF-funded project can be found in Leaves, Winter 2009-10 (Volume 8, Number 1).

Climate Change (continued from page 6) particular is likely to increase in the future as the climate warms, because spring leaf-out will occur earlier in the year, but the frequency of rare extreme freeze events is expected to remain the same. Our data suggest that this type of extreme climate event could be the biggest factor limiting plant growth at Holden. This preliminary study has demonstrated that the Holden plants database holds tremendous potential to address one of the most pressing scientific issues of our time – how do plants respond to climate extremes? As typically happens with scientific studies, however, our results raise new questions. For example, in 2001 we saw that plants varied widely in their growth response to a moderate drought event as shown by large error bars on relative growth rate. Did trees and shrubs or native and exotic species respond differently? We are excited to explore these more complex effects in our full-scale study using the complete database. Finally, perhaps

more exciting is that The Holden Arboretum staff, volunteers and outside researchers have collected data on almost every aspect of the natural areas and collections at Holden. These data could have important impacts on Holden’s mission objectives such as conservation of native forests, but most are still in paper format so they cannot be easily accessed or analyzed. Toward this end, staff and volunteers engaged in Holden’s “Big Data Project” are currently hard at work digitizing this fantastic scientific resource.

Spring 2015

periodicals ®

9500 Sperry Road Kirtland, Ohio 44094 440.946.4400 holdenarb.org

postage paid Mentor, Ohio

Please notify Holden of change of address.

Rouen Lilacs, Syringia x chinensis ‘Metensis’ and ‘Saugeana’ in the Display Garden

JACKIE KLISURIC