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Volunteers at Work

Our grounds volunteers have been back for another summer and have been busy keeping the grounds beautiful and supporting our conservation efforts! Check out what they've been working on.
photo of people working in a garden bed surrounded by low hedgesThe garden volunteers working in the newly planted English Gardens. Photo by Cael Wishart.
colour photo of women weeding invasive species in a forest.Our collection volunteers removing invasive species from the Magnolias section of the World of Trees. Photo by Sadie Campbell.

Trays of Iris brevicaulis and Carpinus caroliniana transplanted by our nursery volunteers. Photo by Sarah Farquharson.

Thank you to all of our volunteers for your time and hard work so far this summer!

Research Feature: Red Mulberry Update

Sadie Campbell, Horticultural Intern

Some of my favourite work that I get to be involved in at The Arboretum is our species at risk conservation efforts. Last month, my co-worker Sarah and I spent two days hiking around the forests and fields of Pelee Island to collect cuttings from the remaining Red Mulberry trees (Morus rubra) on the island, led by former Arboretum Curator, John Ambrose who has been finding, documenting, and monitoring these trees. John is also former Chair of the Red Mulberry Recovery Team and has been working on restoring this endangered tree species for decades.

Photo of a woman in jeans and a t-shirt holding a pole with pruners on it next to a tree in a forest.Pelee Island is the Southernmost inhabited place in Canada, and its latitude combined with the warming effects of Lake Erie make the island milder than the mainland. This, along with the variety of habitats found on the island, including wetlands, forests, and alvars, make it a haven for numerous species at risk in Ontario, including the Red Mulberry. It also was home to some of the most prolific poison ivy I have ever seen. Red Mulberries prefer a moist, deciduous forest habitat, so we spent much of our two days on the island hiking through forests looking for the trees (and occasionally wading through poison ivy). The trees we were looking for were unmarked to protect them, so we had to rely on GPS co-ordinates to get close enough to the trees' location where we then had to look for their massive, sandpapery leaves. Once we found the trees, we took cuttings of the new growth that we brought back to Guelph to try and propagate.
Photo: Collecting cuttings. Photo by Sarah

While going to an island for a work trip seems like a pretty good vacation, this trip was no holiday. It was part of The Arboretum's ongoing effort to preserve the genetics of this endangered tree species. With the help of consultants like John Ambrose, and our friends at the Royal Botanical Gardens, Conservation Halton, and Point Pelee National Park, we have been working to expand our Red Mulberry Gene Bank at The Arboretum. In Canada Red Mulberries are endangered. Found only in Southwestern Ontario primarily in moist, rich deciduous forests of the Carolinian zone, this species has been impacted by habitat loss, disease, and drought. 

With only around 200 trees left in the wild in Ontario, only about half of which are mature trees, the fragmentation of their population makes it difficult for this species to reproduce effectively. Aside from disease and drought which can weaken or kill these trees, one of their greatest threats is the invasive and prolific White Mulberry (Morus alba). These trees were originally brought to North America in an attempt to create a silk industry in the West, and then later as an ornamental fruit tree. They have since been spread by birds and now are found in both urban and naturalized areas across Southern Ontario. More hardy to a variety of conditions, these trees also produce more fruit and pollen than Red Mulberries. This is an issue because both species are wind pollinated and hybridize readily. The smaller populations of mature Red Mulberries tend to be inundated with White Mulberry pollen, making it difficult for them to produce pure offspring. Since the hybrids can display both red and white traits to varying degrees, it always requires genetic testing to be certain about the purity of a Red Mulberry. Testing has found that these hybrid trees often tend to be genetically more like White Mulberries than Red Mulberries, meaning that we are at risk of losing the unique genetics of these Ontario trees.

While Sarah and I were collecting cuttings on Pelee Island, our partners at the Royal Botanical Gardens, Point Pelee National Park, and Halton Conservation were collecting cuttings from their own trees. colour photo of a misty room with trays of plants laid out on metal tables.Our goal is to bring together these separate populations, which were too far apart in the wild to reproduce, and preserve their genetics in our Red Mulberry Gene Bank. Once they mature, their seed can be used for conservation efforts. After the cuttings were collected, we brought them to the Phytotron Lab at the U of G campus where we prepared them to go into a climate-controlled growth chamber. Unlike our greenhouse, in the chamber we can control factors such as humidity, temperature, and light to give our cuttings the best possible chance to root. After hiking through waist-deep poison ivy to collect these cuttings, it's especially gratifying that some of our cuttings are beginning to take root! Once the roots have developed, we will transplant the cuttings into soil. They will remain in the chamber until October, where we can give them an extended growing season to give them a longer opportunity to develop buds for next spring.                           Photo: Our chamber in the Phytotron Lab. Photo                                                                                            by Sadie Campbell.

colour photo of a hand holding a cutting stuck into a peat pot. there is one little root growing through the potcolour photo of a hand holding the same cutting. this time there are several white roots growing through the peat.Photo: The same Red Mulberry cutting, one week apart. Check out that root growth! Photos by Sadie Campbell.

In other exciting mulberry conservation news, seeds collected this year from some of the trees already in our Gene Bank have started to sprout! We also just sowed some seeds collected by John Ambrose on Pelee Island. Once these seedlings have matured, we can test them to find out if they are pure Red Mulberry. If you're curious about how The Arboretum works to restore rare woody plants in Ontario, you can read more about our Gene Banks here!
colour photo of a tray with little green seedlings growing in itThe Red Mulberry seedlings grown from seed collected from our Gene Bank this summer. Photo by Sadie Campbell.

Upcoming Workshops


colour photo of a hand holding a bright green maple leafVirtual Tree Identification 
Do you love trees but can’t tell an Ash from a Walnut, a Birch from a Beech, or a Spruce from a Fir? Are you looking to connect more with the natural world around you? Join Shelley Hunt, U of Guelph course instructor and former Arboretum Director, for a virtual, interactive tree identification workshop. Over the course of 4 Zoom sessions, with hands-on challenges to complete in between, you will learn the basics of tree ID, with a focus on native Ontario species (and their look-alike non-native counterparts). Registration is still open for this course! You will receive a link to the recordings of the sessions that have already passed when you register. Thursdays Jul 7-28

colour photo of a bright green oak leafTree Identification (Virtual and In-person session)
Join Shelley Hunt for an in-person session on The Arboretum grounds to explore tree Identification. This workshop includes the virtual sessions listed and described above. The virtual session is included in the in-person session, so if you are registering for the in-person session you should not register for the virtual session. Registration is still open for this course! You will receive a link to the recordings of the sessions that have already passed when you register. Thursdays Jul 7-28, Aug 4

close up colour photo of the seed casings of a witch hazelVirtual Shrub Identification
Ontario has dozens of native shrub species, from dogwoods to viburnums, blackberries to spicebush, and everything in between. Where to start in learning to identify them? In this workshop, spread over 4 zoom sessions, we will cover basic shrub morphology and learn the key ID features of a wide variety of these diverse woody plants. The 4th session will include a virtual tour of shrubs in the Arboretum's collections. We are also offering an in-person session on Friday, September 30.  The virtual session is included in the in-person session, so if you are registering for the in-person session you should not register for the virtual session. Wednesdays Sep 7-28

close up colour photo of the red fruit of celtis tenuifoliaShrub Identification (In-person and Virtual)
Join Shelley Hunt for an in-person session on The Arboretum grounds to explore Shrub Identification in-person. This workshop includes the virtual sessions described above on. The virtual session is included in the in-person session, so if you are registering for the in-person session you should not register for the virtual session. You will automatically receive the link for the virtual sessions with your registration and the link to the recordings after each session. Wednesdays Sep 7-28, Sep 30

colour photo of a person in blue jeans, a white shirt and hat with long brown hair sitting in the forest in the sunShinrin-Yoku Walk With Ben Porchuk
Inspired by Shinrin-Yoku, a Japanese term that translates into “Forest Bathing” in English, discover a gentle way of moving mindfully through nature. Led by Canada's Forest Therapy Guide and Trainer, participants experience a walk intended to open the senses, deepen a connection with the natural world, and enhance wellbeing. Ben Porchuk is the co-founder of the Global Institute of Forest Therapy. He has led over 50 forest therapy walks in several countries around the world. Sep 14

colour photo taken over the shoulder of a woman who is painting the landscape in front of her with watercolour paintsIn-Person Plein Air Painting
Spend the afternoon plein air painting with watercolour artist Candice Leyland. Candice will show you her approach to painting landscapes outdoors and inspire you to create your own unique paintings of the Arboretum grounds. Students will have plenty of opportunity to receive feedback on their work and a Group Critique at the end of class will give students an opportunity to share their work and learn from each other as well. What a great way to spend a Sunday afternoon! Oct 2

colour photo of someone's hands painting watercolour fall leavesVirtual Paint Fall Leaves in Watercolour
This class covers basic watercolour techniques such as colour mixing, glazing and the wet in wet technique. We will learn how to mix a variety of fall colours and paint beautiful fall leaves. Perfect for absolute beginners. Oct 17

All of our virtual programs are offered live on Zoom, and recordings are made available for registrants to access for a limited time. Visit our website to learn more about these and our other programs. Register early to save your spot!

Wednesday Walks!

colour photo of snowdrops
Wednesday Noon Hour Walks

Nature is known to be unpredictable and unexpected, so what awaits us today? Michelle, The Arboretum's Naturalist Intern, will be leading free 1 hour long walks every Wednesday. Walks start at The Arboretum kiosk at 12:15pm. For more information contact Michelle at or ext. 53615.
Please note that the hike may be cancelled if there is inclement weather. Cancellations are posted on our social media pages.

We kindly ask that walk participants follow the current University Covid protocols. Current protocols can be found here.

Wednesday Evening Walks

Topics for the August Wednesday Evening Walks have been announced! These are the last evening walks of the season, so join Summer Naturalist Christa each Wednesday at the J.C. Nature Center from 7:00 to 8:30 PM for your last chance explore a different aspects of the world around us in these guided tours! 

Aug 3 – Enjoying Nature... For Science!
The Arboretum is the home base for many different research projects! Join us to learn about the cool science The Arboretum has been a part of and how you can contribute by using community science apps and platforms!

Aug 10 – Mother Nature Knows Best
Mother knows best, and that’s no different in nature! From Velcro and umbrellas to computer software, solar panels, and public transportation planning, we as humans have been students of Mother Nature for centuries. Come learn about how everyday aspects of our lives are inspired by nature!

Aug 17 – Nature Drawing
Taking the time to stop and study one aspect of the world around us can help us to not only feel more connected to nature, but also we tend to notice things that we never would have before! If you’re looking to express your creative side, join us for an exploration into nature drawing and journaling.

Aug 24 – Things with Wings
Ever wish you could fly? Sadly, we were not born with the ability to fly, but that doesn’t stop us from marvelling at all the fascinating ways animals use flight. From birds and bats, to insects and flying squirrels, join us as we explore the world of flight!

Aug 31 – Fantastic Fungi
When we think of fungi, we often think of mushrooms, like those we see at the supermarket or ones that poke through the ground in our lawns. But the world of fungi is so much more diverse, and much of their lives are hidden from our view! Join us to learn about fungi and their roles in the ecosystem as decomposers, nutrient recyclers, and symbionts.

Suggested donation of $2 per person and free for kids under 5. If you have any questions, feel free to reach out to Christa at We can’t wait to see you there!  

The Arboretum's Soil

Michelle Beltran, Naturalist Intern

Let’s get one thing straight, it’s soil not dirt. Soil is rich in minerals and nutrients. It takes many, many years of rock erosion and organic matter decaying for soil to form. Most importantly, soil is alive. Dirt on the other hand, is only composed of sand, silt, and clay. Dirt isn’t full of life, and it alone cannot support much life.

colour photo of a core dug into the soilSoil can vary depending on what it’s made up of. The Arboretum sits on limestone bedrock several meters below the ground’s surface. The limestone bedrock has caused our soil to be more basic. The scale that measures acidity is the pH scale, which ranges from 0-14. 7 is considered neutral. Many plants prefer soil that is slightly acidic, with a pH measurement of 6. The soil in The Arboretum is on the higher end of 7. The exact composition of our soil also varies throughout our grounds. In some locations our soil is rich in clay, which allows the soil to retain moisture. In other locations, like in the gravel pit, the soil is sandier and more porous.

Our grounds are home to native Ontario trees, along with trees from around the world. There is a plethora of challenges tocolour photo of a young red mulberry tree growing trees that don’t necessarily want to live in Southern Ontario, soil composition being one of them. Having a more basic soil can make it difficult for some plants to absorb iron from the soil, this causes leaves to turn a yellow color. Some trees, like this red mulberry, prefer moist, rich, loamy soils, but can also be found growing on sandy beaches or cliff edges. Our horticulture team can amend the soil around the trees that struggle to grow in our native soil by adding dirt that’s rich in sand or by adding specific nutrients to the soil.

So, what’s the dirt on soil? Turns out it’s much more complicated than most people (including myself) would think. Some plants thrive in The Arboretum’s soil, while others require lots of care from our horticultural staff. Next time you hear someone refer to soil as “just dirt” remind them of how much more soil is.

Top: soil core dug in The Arboretum grounds. Photo by Michelle Beltran. Bottom: a young Red Mulberry (Morus rubra) growing in The Arboretum grounds. Photo by Michelle Beltran.

What To See

To learn more about what is happening or what to look out for at The Arboretum please follow us on social media. We are on Instagram, Facebook and Twitter. Search for us at @uogarboretum.
[Click on the photos below to see the posts and more on Instagram.]

colour photo of a moth with a black and beige pattern on its wings resting on someone's hand. there is a hint of a bright pink-red and black pattern on its body under its wingsSuppose you don’t want to get eaten. One way to do this is to be able to eat toxic compounds (without dying yourself) and store them in your body so that you are toxic to your predators. Great strategy, right? But, your predators need to know that you are toxic because otherwise once they feel sick from your toxins, you are already being digested which is undesirable. The Virgin Tiger Moth caterpillar stores toxins in its body that are still there after it transforms into a flying adult moth. The adult moth, incredibly, covers four of the five senses to make sure its predators know it is not to be eaten.

1. It has a striking pattern and very bright pink underwings that it can flash when needed. This visual cue works well to deter bright-eyed birds.
2. A flying tiger moth can not only hear bats approaching, it can emit its own sounds that either startle the bats, tell the bats that the moth is toxic or scramble the bats sonar so the moth can escape. Sound cue…check.
3. Tiger moths smell gross. This olfactory cue likely works well on sniffy small mammals such as shrews and mice.
4. Virgin Tiger Moths can produce a bubbly foam (note the bubble near the head of this one) that tastes horrible and can also deter predators. Cue number four!
Quadruple Threat! Hmmm, the caterpillars have long hairs that may be irritating when touched…Quintuple Threat!

colour photo of red tailed hawk perched on birdfeeder with one foot raised. The bird is facing the camera and holding one of its tail feathers in its beak.Our resident bird feeder Red-tailed Hawk is going through his first ever molt! Each year birds molt, or shed, their feathers, allowing them to get rid of damaged or worn feathers. As this young fellow molts his tail feathers, we can see him transition from his juvenile brown tail to his adult red tail!

colour photo four grey young house wrens crowded together in their nest hole in a treeHow many House Wren nestlings can you count? There are actually four in this shot but there could be more stuffed in there! Most of the wren nests we see are in our bird boxes so it was nice to find this one in a natural cavity in one of our planted Balsam Poplars. Black-capped Chickadees have used this spot, too. Natural cavities and old woodpecker nesting holes are in high demand and can be a factor that limits population size in species that often don’t make their own cavities such as wrens, chickadees, swallows and bluebirds. You can help these species by putting up a bird box in your backyard or leaving a tree stump standing so woodpeckers, and then later these birds, can use it.

Outdoor Wedding Ceremonies at The Arb

two photos side by side. the first is a picture of pink peony flowers with conifer trees in the background. The second is an aerial photo of a garden bed with peonies and conifer trees.
Looking for somewhere to host your outdoor wedding ceremony? The Conifer Outdoor Ceremony Site is a beautiful, secluded one-acre green space nestled within our Conifer Collection. It is a separate location from the OAC Arboretum Centre rental for ceremonies only, with free parking, use of the site from dawn until dusk, and a garden featuring tree peonies that flower in late spring and Japanese anemones that bloom in late summer and early fall. 

For availability, rental rates and reservation, contact Dawn Ann Webster at 519-824-4120 ext. 54110 or

From the Archive: Dawn Redwood (Metasequoia glyptostroboides)

Henry Kock

You can have a lot of fun rolling this elaborate name off your tongue. Meta (similar to) sequoia; glyptostrob (a rare genus of tree in China with alternate leaves); oides (in the likeness of). It is a leaf‑losing conifer related to bald cypress, in the family Taxodiaceae but differing from all other members in having an opposite leaf arrangement and a cone that looks like sequoia.
Dawn Redwood carries a most remarkable botanical story. It was thought to have become extinct 5 million years ago due to the pressures of the ice ages. It was known by fossils recorded from throughout the northern hemisphere, including the Canadian Arctic, where it was believed to have originated about 80 million years ago ‑ the arctic land mass has since shifted northward.
It became a “living fossil” in 1945. Hsueh Chi‑ju, had just graduated from the Forestry Department in the National Central University at Chungking, China. As a specialist in conifers, he was intrigued by a leaf and cone specimen of an unknown tree that was sent in from Madaoqi (knife grinding) village in Wanxian county. The notes from the regional forester described a colossal tree in a remote village that is actively protected with a shrine because it is believed to be a divine tree. The leaves seemed familiar to Hsueh Chi‑ju but were arranged opposite on the branch, unlike other members of the family Taxodiaceae in which it seemed to fit. The specimen didn’t give any indication as to how the cone was placed on the stem and he realized that he must go to the reported tree, to get a better specimen of what the local villagers call “water fir”.
graphite illustration of a cone from a dawn redwoodblack and white photo showing the opposite leaf arrangement of dawn redwood Left: the cone of a Dawn Redwood. Illustration by Kye Schuett. Right: leaves of a Dawn Redwood. Note the opposite leaf arrangment. Photo by Henry Kock.

Hsueh departed for south central China in February to get the dormant flower bud bearing branches that are characteristic of the family. The trip to Madaoqi was arduous ‑ two days by steamer up the Yangtze River and then a 120 km walk to his destination. There was no road and the trip was made on trails less than one foot wide, threading through the mountains. These conditions made robbery and murder a distinct possibility but he arrived safely after only three days walking. Tired, hungry and thirsty, he wasted no time in looking for the great tree before it was too dark. Finally, he stood under the leafless giant only to realize that the branches were too high to be reached and the tree was far too large to climb. He resorted to throwing stones and sticks up into the branches and finally a few flowers came down. He was overcome with joy that there were both male and female flowers present. The next morning he began the journey back to civilization with his treasure.
At the university, little time passed before the forester realized that the unusual tree in Madaoqi was a species that was thought to be extinct. Later visits confirmed that it was one of only a handful of the trees still alive. Dawn Redwood is now protected from extinction in China by the Forest Service and seeds were sent to several Arboreta and Botanic Gardens in 1948. Seeds from these rapid growing trees are now being exchanged by horticulturists throughout the Northern Hemisphere. A species from the dawn of time is safeguarded by village ritual and with the help of botanists is redistributed across its historical range ‑ kind of a home coming.
You can see one of the earlier planted Dawn Redwood trees (perhaps 40‑45 years old) at St George’s Anglican Church on Woolwich St. Guelph, at the front corner closest to the Speed River pedestrian bridge. You can also find a pair of thirty year‑old specimens in the World of Trees collection in The Arboretum by following the self guided brochure for the collection. They stand along the east side of the creek, just north of the Ivey Trail bridge.
colour photo of two trees growing next to a streamThe two Dawn Redwoods next to Flying Fish Bridge in the World of Trees in 2022. Photo by Sadie Campbell.

This article was originally written by Interpretive Horticulturist Henry Kock 19 years ago for our Fall 2003 Green Web Newsletter (any readers remember the Green Web?). You can read more about Henry and his legacy both at The Arb and in the community here. The Green Web newsletter in which this article was originally published (and other back issues of our newsletter in its various iterations) can be found on the Newsletter page of our website. You can still see the Dawn Redwoods described at the end of the article in our World of Trees Collection next to the Flying Fish Bridge, now almost 50 years old. 

In the Ecosystem

Join the Guelph Institute for Environmental Research (GIER) on Wednesday, August 10th, 12:00pm-1:00pm EST for a new installment in their Environment Bound series. Amy Brady and Tajja Isen will discuss of their new anthology, The World As We Knew It: dispatches from a changing climate, and answer questions about the daily and personal effects of climate change, and how storytelling can be an essential part of combating climate change. Hear about this intimate portrait of a climate-changed world, a collection of voices describing lives and memories of familiar activities and places that have been transformed in small and large ways.

The Environment Bound series transcends the boundaries between creativity and critical thinking, inviting creative writers (writing in any genre) to speak on their work at the nexus of research and writing in any aspect of the environment.

colour photo of a group of men standing in front of a garden bed with a flower-covered tractor in the middle of it.
Check out the newest flower garden created by our friends at the Guelph campus grounds staff! After an old tractor was left on campus as a prank by some students from Western University, the grounds crew used the tractor to create a floral display. You can find this new bed in the Conservatory Gardens by the Rutherford Conservatory near the University Centre. Read more about this project here!

Donation and Dedications

red cardinal flowers planted alongside a boardwalkThis spring, we were busy with forest restoration plantings in The Arboretum that were made possible through the Wall-Custance Memorial Forest program. The Memorial Forest is a partnership began in 1989 with the Wall-Custance Funeral Home and Chapel in Guelph. For each donation to the Wall-Custance Memorial Forest Program, a tree or shrub is planted in the Memorial Forest using 16 species of native trees and 10 species of native shrubs as part of reforestation efforts across The Arboretum. These forested areas serve as windbreaks, screening, wildlife corridors and habitat for many species. Ten percent of each donation to the Memorial Forest program is added to The Arboretum Endowment Fund to support development and maintenance.  Since 1989, over 18,000 trees and shrubs have been planted in memory of loved ones. For more information please visit the Wall-Custance website or call the Wall-Custance Funeral Home & Chapel at (519) 822-0051, or The Arboretum at (519) 824-4120 ext. 52113.
Gifts to the Arboretum are tax deductible. Join our community of supporters today with a gift through our online donation portal. 

We can accept donations of shares and in-kind contributions of appreciated securities. Donors receive full tax credit for the fair-market value.

Contact our director, Justine Richardson, to discuss how you can help.


colour photo of a stack of dark grey t shirts with a circular green logo on them. The logo is a tree with different kinds of leaves on it surrounded by a circular pattern of leaves from different species of tree.
Arboretum t-shirts are a staff favourite. Made in Canada, these shirts are a super soft organic cotton/bamboo blend (but don’t feed it to your panda), and feature the leaves of 16 different tree species and The Arboretum's logo. The common and Latin names of the tree species are listed on the back of the shirt. Use it as both a t-shirt and a very portable (and stylish) guide to tree leaf identification!

Visit our Merchandise shop to order today or to check out our other cool products and educational materials.

Ways you can connect with The Arboretum

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camera icon for photo creditThe header of this month's newsletter is of staghorn sumac in bloom. Photo by Sadie Campbell.