The Quarterly Journal of the Mary May Binney Wakefield Arboretum ___________________________________

Volume Five, Issue 1 - Fall 2022

Oaks, Quercus

At last count the Mary May Binney Wakefield Arboretum is home to seven identified species of oaks. They include northern red oak (Quercus rubra), white oak (Quercus alba), black oak (Quercus velutina), pin oak (Quercus palustris), swamp oak (Quercus bicolor), bur oak (Quercus macrocarpa), and scrub oak (Quercus ilicifolia). Many of these trees are over 100 years old and provide food for more than 100 species of birds and mammals, and thousands of species of insects, amphibians and worms. For this reason, oaks are considered a “keystone species” for without it many of these mammals and insects could not survive and health of the local ecosystem would deteriorate. Oaks are very important in carbon sequestration, water management and have proven to be highly adaptable to variations in weather which is extremely important in the face of climate change.

In his recent book The Nature of Oaks, Doug Tallamy states that “75% of the food necessary to sustain birds and other mammals is produced by just a few plant genera. They are oaks, hickories, cherries, willows, birches, pines and maples.”¹ There are several reasons for this phenomenon. Oaks have been around for a long time, evolving over the last 60 million years. They have very long life spans, are drought tolerant, fire resistant and quick to migrate as temperatures and climates change. Oaks also have a penchant for hybridizing, which allows them to adapt to rapid environmental changes more quickly than other species. There are more than 600 species worldwide and 90 species of oaks in North America alone.

In his book Tallamy focuses on the important relationships between the oak and the more than 500 species of caterpillars that depend on it for food. These caterpillars are the most important source of food for numerous species of birds feeding their young in the spring. Tallamy explains that unlike many adult birds, baby birds cannot digest nuts and seeds but depend on insects and caterpillars for survival. As migrating birds return to their native range, they depend on these oak species to provide food in order for their progeny to survive. In the United States, more than 100 birds and mammals use acorns for food. Since acorns contain carbohydrates, protein, and fat, they are a great source of energy. Oak leaf litter also provides major sources of nutrients and cover for species of amphibians, worms and microbes. Oaks also have a fascinating life beneath the surface of the ground that is just beginning to be understood. They have a massive root system which relates with mycorrhizal fungi to make copious amounts of carbon rich glomalin, a highly stable glycoprotien that gives soil much of its structure and dark color.²

Goldenrod, Solidago

Although goldenrod is a herbaceous perennial and not a woody plant, it is an important plant in the Wakefield Arboretum collection due to its crucial ecological value. It also adds great summer and fall color to the landscape. Goldenrod belongs to the Asteraceae family—a very large plant family that includes dandelions and daisies, tansy and thistles, artichokes and sunflowers. Most of these plants are herbaceous perennials but also includes shrubs, vines, and even trees. Goldenrod, or Solidago is a large family with up to 120 species and many cultivars. One reason that most people refer to goldenrods as a group is because they are very hard to identify by species. The genus name, Solidago, is Latin for Solidus and means "to make whole." This references the plant's healing properties, which include reducing inflammation, relief of muscle spasms, fighting infections, and lowering blood pressure. Native Americans used this plant for medicinal purposes.

 Goldenrod Gall Fly gall Photo by Mark Etheridge

Goldenrod is often confused with ragweed and wrongly accused of bearing the wind-borne ragweed pollen that causes many allergies and hay fever. Unlike ragweed pollen which is spread by the wind (thus making you sneeze), goldenrod pollen is dense and heavy, therefore it relies on insects to move pollen from one flower to the next.

The plant produces copious amounts of nectar as an attractant, allowing many different pollinators the opportunity to feed and spread the pollen.

Goldenrods provide more than just nectar and pollen for some species. Certain species of flies and moths depend on the goldenrods to provide a safe hiding spot for their young. These insects lay their eggs inside the stem of the goldenrod and the goldenrod responds by creating a gall or growth. According to an article in Backyard Ecology: Exploring Nature in Your Backyard, when the insect egg hatches, the larvae begin eating the goldenrod from the inside, but it doesn’t seem to affect the health of the goldenrod except to stimulate the production of the gall. The moth larvae only spend part of one season in the gall, hatch and moves on. However, the fly larvae spend almost a year in the gall, providing a source of food for several species of parasitoid wasps that specialize on goldenrod gall fly larvae. According to Shannon Trimboli “These parasitoid wasps only lay their eggs in goldenrod galls. The female will insert her ovipositor into the gall and lay a single egg. When the egg hatches the wasp larvae eats the goldenrod gall fly larvae. Even if a parasitoid wasp doesn’t find the gall, the fly larvae isn’t necessarily safe due to the fact that several bird species are known to hunt for and tear open the galls then eat the developing larvae during the winter.”³ This is another reason to leave goldenrod standing during the winter months.

In the woodland areas of the Mary May Binney Wakefield Arboretum extensive remediation was done to remove invasive species. After the removal of invasive species including buckthorn, bittersweet, black swallowwort, barberry and honeysuckle, goldenrods began to colonize these areas. Once established, these goldenrod meadows are maintained to encourage further healthy native plant communities to thrive while offering a great variety of sources of food for native birds and insects.

Fuzzy deutzia, Deutzia scabra

Like a bedazzled dress or a veil of white and green each June, the Mary May Binney Wakefield Arboretum’s fuzzy deutzia is a real showstopper. Often more people comment on the beauty of this plant than any of the blooming kousa dogwoods. Although there are native deutzias the Wakefield Arboretum plant is the species native to Japan and China. The shrub grows 6-8 feet high and almost as wide and in June becomes nearly completely covered in 5 petaled star- shaped white flowers that last for two weeks. Deutzia scabra is named for the scabby or exfoliating bark on mature shrubs. Often termed “an old fashioned plant” due to the fact that they were passed on from one generation to the next the duetzia can be used as a border or privacy screen. The flowers are in panicles or corymbs typically white with a tinge of pink and seeds grow as 3 to 6 closely spaced panicles along the branches. The plants are disease and deer browse resistant. Deutzia was named after Johan Deutz, a patron of the plant explorer Carl Peter Thunberg who collected it in Japan in late 1700’s.

Sugar Maple, Acer saccharum

Standing like a sentry in the center of the circle lane entrance to the Isaac Davenport mansion is one of the oldest and most recognizable trees in the arboretum, the venerable sugar maple (Acer saccharum). The grand sugar maple at the entrance to the Davenport Mansion is believed to have been planted around the time of the Civil War; if correct, that would make the tree about 160 years old and one of the oldest trees in the collection. The sugar maple is a species of flowering plants in the soapberry and 

lychee family Sapindaceae. Worldwide there are approximately 132 known species of maples. The sugar maple is native to the hardwood forests of eastern Canada and eastern United States. The strength of this wood is reflected in the genus name, Acer (Latin for sharp), referring to ancient Rome's use of maple to make handles for spears; 'saccharum' is the Latin word for sugar and refers to the high sugar content in this species' sap. One of the most iconic trees to New England, the Sugar Maple is best known for its majestic stature, its beautiful fall foliage, and, of course, its sap - which is boiled down in evaporators to produce maple syrup. 

If healthy, and with the right growing conditions, sugar maples can live a long, long time - up to 300 to 400 years. The oldest known sugar maple is thought to have lived for over 731 years in Ontario, Canada; called “The Great Wishing Tree,” this particular sugar maple hosted many gathering and meetings under its branches over many years.⁴ Sugar maples are resilient to drought and grow in a variety of soils. They are highly adaptable and can grow in zones 3 to 8, which encompass much of the United States. As we experienced the excessive heat and drought during the summer of 2022, the sugar maple that welcomes visitors to the Isaac Davenport mansion showed very little stress and die-back, not to mention its autumn colors are as bright and vivid this year as any other year.

Being one of the largest trees in the collection, it is also a favorite of many children who gaze in awe up at its tallest branches and marvel at its height. With some well deserved TLC, we hope that our beautiful sugar maple will welcome visitors for another century or more.

The sugar maple is often confused with Norway maple, which is not native to the United States but is commonly planted in cities and suburbs. They are also not closely related within the genus. The sugar maple is most easily identified by breaking off a leaf and observing it’s sap at the base of its stem. The sap of the sugar maple where the stem of the leaf meets the branch, its petiole or stalk, is clear while the sap of the Norway maple is white. In the spring, the sugar maple displays brown, sharp-tipped buds while the Norway maple has blunt, green or reddish-purple buds. The bark of the two trees is also distinctive: the sugar’s bark, especially on older trees, is shaggy and deeply rutted while the bark of the Norway is less so. The leaf lobes of the sugar maple have a more triangular shape, in contrast to the squarish lobes of the Norway maple. If you have a known sugar or Norway maple leaf for comparison, you’ll also see that the leaves of a Norway maple are broader compared to their height than those of sugar maple. Lastly, Norway maple leaves have more lobes, typically five to seven, compared with the sugar maple’s three to five, and the indented portion between the lobes of sugar maple will be more rounded.

Photo courtesy of Oregon State University

Lacebark Pine, Pinus bungeana

Planted in the corners of the arboretum’s Piazza Lawn behind the Isaac Davenport Mansion are two lacebark pines (Pinus bungeana). One is large and mature, planted by Polly Wakefield decades ago and originating from the Arnold Arboretum in Boston. The other is a young tree, planted in 2016 to replace a lacebark that has been damaged by storms.

Native to northern and central China, the lacebark pine is considered to be among the most beautiful ornamental conifers. This plant was identified by plant explorer Frank Nicholas Meyer when he conducted a plant collecting campaign in China, Northern Korea, Siberia and central Asia for the USDA in 1905. He was sent to collect plant material that might be economically useful if grown in the United States. He spent 13 years returning several times to the US, and collected 2000 species of plants. David Fairchild, a plantsmen of great renown, made an arrangement with the Arnold Arboretum director to collect plants for the Arboretum at the same time. The Arboretum’s archives have an image of Frank Meyer standing next to a massive Pinus bungeana at the Princess tombs near Bejing.  According to Frank Meyer’s papers, he collected samples of Pinus bungeana on his first excursion in 1905 and sent them to the Arnold Arboretum and the USDA headquarters.⁵

Paperbark maple, Acer griseum

From the trees in Wakefield Arboretum collection, it is clear that Polly was fond of trees with peeling - or exfoliating - bark. Of the various maples that Polly planted, none has a bark more identifiable than the paperbark maple (Acer griseum): its red, paper-thin peeling bark fits the tree’s name. Of the four or five mature paperbarks in the collection, the most prominent is located behind the Issac Davenport mansion, centered between the two lacebark pines planted in the corners of the piazza lawn.

Paperbark maple is native to central China. It was introduced into cultivation in 1901 by E.H. “China” Wilson when he made his first collecting trip for Veitch Nursery in England. In 1907, Wilson was hired by the Arnold Arboretum in Boston and when he arrived from England, he brought two paperbark maple trees with him. These two trees and the seedlings they produced became the primary source of most paperbark maples in the United States creating a very narrow genetic base. This made the trees more susceptible to pest and disease outbreaks and less likely to survive a varied climate.⁶

According to an article written by Paul Meyer, a member of this expedition team discovered a grove of wild paperbark maples on Wudang Mountain in Hubei China in 1994. Wudang is the site of a famous Taoist temple with forests that have been relatively well protected. The expedition team found the paperbark maples at an elevation of three thousand feet in a grove that also included Stewartias, Cornus kousa, and Cornus controversa. The Expedition team dubbed this area “horticulture heaven" due to the rich diversity.⁷ Polly Wakefield, an avid collector of all of these species, would have loved to observe this collection of plants in the wild!

One contributing factor to that lack of genetic diversity in paperbark maples may be due to the fact that paperbark maple frequently produce empty samaras with no viable seeds. In fact often less than 5% of the samaras have viable seed making the plant much less likely to produce seedlings. This is an interesting note in relation to the Wakefield collection.

It is not uncommon to find beautiful and healthy seedlings throughout the landscape. Staff members often dig these young plants and sell them or replant them in different parts of the arboretum.

Paperbark maples are now endangered in its native China. That designation makes it even more essential to grow and safeguard wild collected specimens in places like the Mary May Binney Wakefield Arboretum and other plant collections throughout the world.The paperbark maple is one of the trees in the collection we encourage visitors to touch and rub - the thin bark easily peels away in one’s hands. The next time you visit, look for the mature paperbarks and take a moment to marvel at their beauty and uniqueness.

Shag Bark Hickory, Carya ovata

Shagbark hickory is a beautiful native tree that provides year-round interest in the garden and food for many native species. The Mary May Binney Wakefield arboretum has several old specimens throughout the landscape. The oldest and largest plant is on the lower border of the property obscured by a grouping of large arborvitae. It is unclear whether this tree was planted by Polly Wakefield or was a “volunteer"- growing from a hickory nut dropped by a bird, squirrel or other animal.  Like many plants discussed in this quarterly shagbarks have unusual stunning bark that forms foot-long crescents often peeling from both ends. Flowers emerge in mid-spring. Male, pollen-producing flowers are gathered in green hanging clusters called catkins. Female flowers, which give rise to fruit, form in spikes. Hickories are members of the walnut family, and the fruit of the shagbark hickory is highly prized by both humans and wildlife. The fruit is a nut with a hard outer husk that splits open when ripe. Like the native oak, shagbark hickories are an important part of the local ecosystem. Black bears, foxes, mice, chipmunks, squirrels, rabbits, and a number of birds enjoy the nuts every fall. More than 133 fungi are associated with shagbark hickories, but there are few which damage the tree seriously. Shagbark hickories also host approximately 180 species of insects and mites, but bark chemistry and architecture minimize their incursions. Bats and brown creepers roost and nest beneath the shagbark’s flaking bark.⁸

Like our native oaks, shagbark hickories go through a process known as “masting." Every few years the trees produce much larger quantities of nuts and acorns than at other times. There are many theories as to why this may occur. According to Andrew Hacket-Pain in an article written for Current Biology, the first explanation is the pollination efficiency hypothesis. "Most plants are self-incompatible (unable to be fertilized by its own pollen) and concentrating flowering into occasional mast years increases the efficiency of pollen transfer between individuals. The second explanation is based on the observation that years of low seed production starve seed consumers, whose reduced populations are overwhelmed by subsequent large seed crops. This strategy reduces the overall proportion of seeds lost and is known as the predator satiation hypothesis".⁹

Part of the Arboretum certification process includes sharing plant records with similar organizations, both nationally and internationally. Wakefield plant records have been shared with organizations including BGCI (Botanical Gardens Conservation International). In 2021, the arboretum was asked to provide information to the BGCI network about the shagbarks here on the property. This information was being collected from gardens and arboreta all over the country to inform conservation actions related to native species that produce nuts and fruit.

4. https://ottawarewind.com/2019/07/28/the-great-wishing-tree-in-search-of-the-worlds-oldest-maple-tree/)

5. Frank Meyer https://www.biodiversitylibrary.org/page/52562868#page/86/mode/2up

6. https://arboretum.harvard.edu/plant-bios/paperbark-m

7. Meyer, P. W. 2010. Paperbark maple: Acer griseum. Arnoldia, 68(2): 48–50.

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