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From the Gene Banks: Seed Collection

Sarah Farquharson, Greenhouse Technician
Seeds, seeds, seeds, this fall has been packed! As summer has drawn to a close, and the fall colours set in, with them has come a wonderful abundance of fall fruits, nuts, and other seeds. This year has been especially fruitful in some of our gene banks such as the flowering dogwood (Cornus florida), the cucumber magnolia (Magnolia acuminata), and the tulip tree (Liriodendron tulipifera). These are just a few of the main crops that arboretum staff are collecting as the season progresses. As you walk through the arboretum this fall, you may notice the redbud (Cercis canadensis) loaded with fluttering seedpods, or need to watch your head as the scurrying squirrels knock buckeyes (Aesculus glabra) down onto the trails below. Looking for seeds among the shrubs and trees can be another activity as you enjoy your favourite walks on these crisp autumn days.

Left: Cucumber Magnolia (Magnolia acuminata) seeds starting to peek out from their pink seed pods. Right: Flowering dogwood (Cornus florida) seeds amongst the fall foliage. Photos by Sarah Farquharson.

Upcoming Workshops

colour photo of a bird with a speech bubble that reads bring your garden and nature questionsAsk The Arb
New! Noon-hour session covering Q&A topics from horticulture to birding! Whether you're worried about a plant in your garden or curious about an odd bird behaviour, join Interpretive Biologist Chris Earley and Horticulture Manager and Curator Sean Fox for a monthly discussion. Oct 26

colour photo of stones in cocentric circles on the beachEco-Art Therapy with Memona Hossain
During this 8-week course, participants will explore introductory concepts of Eco-Art Therapy and participate in hands-on learning experiences that are embedded in our nature-connective relationships. No previous learning or experiences required! Sessions are recorded, so sign up now to catch up on any that you may have missed! Sept 14 - Nov 2

Colour photo of birds with labelsVirtual Bird Identification with Chris Earley
Birding has become an even more popular hobby now that more people are home and enjoying nature. Why not take it to the next level? This workshop series includes eight noon-hour lectures on eight different bird groups: hawks, ducks, sparrows, sandpipes, gulls, spring warblers, fall warblers, and spring migrants. ID techniques, field marks, shapes, behaviour clues, and more will be covered! Starts Oct 22

photo of a night sky framed by silhouettes of treesVirtual Constellation "Walk" with Trevor Chandler
Join us for monthly sessions as we get to know the night sky a little better. Participants will be introduced to prominent stars and constellations, where to look for them and how the motions of planet Earth cause them to appear to shift from hour to hour and month to month. You will receive a downloadable star map to help you make your way through the stars! Oct 28

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!

From the Collection: American Witch-hazel

Sadie Campbell, Horticultural Intern

Yellow flowers of the American Witch-hazel.
How do the trees at The Arboretum prepare for Halloween? For the American witch-hazel (Hamamelis virginiana), late October means putting on a brilliant yellow floral display. This large native shrub is one of the last plants to flower at The Arboretum, and its clusters of fragrant, spidery golden flowers are well worth the wait. The flowers are usually yellow but can be tinged with red or orange and have four long, thin, crumpled petals that unfold from small round buds. They begin to emerge in early to mid-fall, persisting into late fall as the leaves drop, sometimes lasting in to winter! Fertilized flowers form into green capsules containing 1-2 seeds that take a full year to mature, hardening and turning brown the following fall when the flowers begin to bloom again. As the capsules dry, they explode, firing their hard black seeds up to 10 metres away! Witch-hazels also have bright green summer foliage that turns a deep golden in the autumn. Its spreading, crooked, multi-stemmed irregular form and smooth gray bark make this shrub striking in all seasons. If you’re looking to add some fall and winter interest to your property, American witch-hazel may be the perfect addition to your garden!

Colour photo of a hand holding shiny black seeds over a bowl of brown seed husksThough it may not have anything to do with witches, the witch-hazel does have a significant relationship to folklore and superstition. This is referenced in the unusual English name of this plant. While “hazel” comes from the slight resemblance of the fruits and foliage to that of the shrub hazel (Corylus)¸ “witch” refers to a historic use of the wood. The branches and twigs of witch-hazels are actually one of the preferred materials used to make dowsing rods! Dowsing (also called divining, or water witching) is the practice of using a Y-shaped stick to detect underground water or other buried objects and materials, such as metals, gemstones, and oil. The dowser holds the two ends of the forked branch palm-up, with the third (the stem of the Y) pointing straight ahead. They then walk around an area where they suspect to be buried water, objects, or materials. As they pass over the object they seek, the tip of the dowsing rod dips towards the ground, seemingly on its own! The “witch” in witch-hazel is thought to come from the Anglo-Saxon word “wych”, which means bend, probably referring to the way that the tip of a dowsing rod bends towards the ground.

Dowsing is definitely interesting, but unfortunately there is no scientific evidence backing its efficacy. The motion of the dowsing rod as it dips towards the ground is attributed to the ideomotor effect, a psychological phenomenon where a person moves unconsciously in response to a thought, idea, or belief. Basically, the brain believes in something or anticipates a specific result, and the body responds by moving subconsciously to make the desired result happen. This is actually the same principle behind Ouija boards! Regardless, American witch-hazel is still worth seeing for its spectacular fall display. Be sure to check out the American witch-hazel on your next walk through The Arboretum. There are some in the World of Trees and the Roots and Shoots Garden in the Centre Forest, but the best place to see their flowers is by the campus entrance parking lot near the Hospice Lilacs!

Top: The yellow flowers of American witch-hazel (Hamamelis virginiana). Bottom: Shiny black seeds and dry seed capsules collected from American witch-hazels by Arboretum staff. Photos by Sadie Campbell.

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 orange coral fungus Corals aren’t only for oceans, sometimes you stumble across them in the forests too…coral mushrooms that is! Check out this cute little Golden Coral Fungus mushroom. This species is saprobic (obtains its nutrients from decaying organic matter) and we’re happy to see it working away at cycling the nutrients in our forests as part of the decomposer community!

a colour photo of two work study students installing a sign The International Institute for Critical Studies in Improvisation (IICSI) has installed a series of signposts throughout The Arboretum. You can access recordings of improvised musical performances filmed in The Arboretum by scanning the QR codes found on the signposts. These self-paced stations can be enjoyed at your leisure over the coming months!

colour photo of a flooded maple forest with fallen leaves floating on the water Have you visited our ephemeral pond in Wild Goose Woods recently? A boardwalk spans over an area of the woods that is typically flooded in the late winter and spring. Usually, these temporary wet woods are dry in the summer, fall, and late winter, but the rainy weather recently has led to the area being flooded again this fall!


October Arb History: The Arboretum Centre

black and white photo of a field planted with conifer saplings with a building in the background
Tokyo Japan, Riyadh, Saudi Arabia, and Guelph, Ontario – what do all these cities have in common? Like Tokyo and Riyadh, The Arboretum in Guelph is home to a building designed by award winning Canadian architect Raymond Moriyama – The O.A.C. Centennial Arboretum Centre! If you haven’t been to the Canadian Embassy in Japan or the National Museum of Saudi Arabia, you may have visited some of Moriyama’s other famous buildings in Toronto, including the Ontario Science Centre, the Bata Shoe Museum, and the Toronto Reference Library. Moriyama’s ability to connect the built environment to the natural landscape is evident in his design of The Arboretum Centre. Embedded in the surrounding hillside the building blends into its environment, allowing visitors’ attention to be drawn to nature - perfectly in keeping with ethos of The Arboretum. Its large windows, courtyards, and patios create a seamless transition between indoor and outdoor space, while also providing lots of natural light. As Raymond Moriyama celebrated his 92nd birthday this month, we wanted to recognize his lasting impact on The Arboretum. Next time you walk around The Arboretum, take a moment to explore the architecture of this unique building! The building is currently open for organized events only, but its pond, gardens, patios, and outdoors spaces are still welcoming visitors. If you would like to learn more about Raymond Moriyama, check out this documentary produced by TVO about his life and work!
black and white photograph of architect Raymond Moriyama
Top: The O.A.C. Centennial Arboretum Centre in 1974 as seen across our West Lawn and nestled into what we now call “Centre Forest”, which now includes the Roots and Shoots garden. Bottom: Architect Raymond Moriyama. Photo by John McNeil for the Globe and Mail.

Arboretum Rentals

Colour photo of a couple getting married under the orange fall foliage of a maple on the west lawn beside the gazebo.

The weather is getting colder, but you can still hold your event at The Arboretum! We can now host outdoor and indoor ceremonies following the guidelines of the University and the province's public health rules. We have newly renovated barrier free access to The Arboretum Centre and Step 3 safety measures including limited capacities.

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

Photo of The Arboretum Centre Auditorium set up for a wedding by Aimee Nicole Photography, 2019.

From the Forest: Black Knot Disease

Casey Howard, Summer Student

colour photo of black knot fungus on chokecherry

Black knot is a disease caused by a fungus called Apiosporina morbosa apart of the phylum Ascomycota and affects plant species in the Prunus genus, which includes flowering and fruit trees. Affected species include both wild and cultivated plum, numerous cherry species including (but not limited to) black cherry, chokecherry, and sand cherry, and rarely apricot, peach and nectarine. Black knot is endemic to North America but is more prevalent in the northeast. In the Arboretum, you can find black knot along a side trail connecting the Maple Collection with the Wall-Custance Memorial Forest trail and sometimes in the Wild Goose Woods.
colour photo of black knot fungus on chokecherryThe main diagnostic symptom of black knot is abnormal swellings on the tree’s branches, with the disease named for the black swellings often described. Infection usually isn't apparent until the knots appear on the tree branches almost a year after initial infection. The first symptoms of the disease look like small brown swellings which will eventually turn olive green and have a velvety texture. As the knots mature and darken, they become hard black tumor-like growths called galls that can range between 2 to 25 cm long. Infected branches are often curved to one-side due to the uneven extra cellular growth of the gall. Galls will continue to expand in size with age and they often end up encircling the entire twig and killing the infected limb. Fruit, leaves, and flowers on the tree are not infected with the fungus, as it only infects woody tissue, but because branch growth is limited with the growth of the galls, leaves, shoots, fruit, and flowers often wilt and die on diseased branches. In the spring during a period of warm and rainy weather, spores (called ascospores) are ejected from spore-producing structures called asci that are present on the surface of the galls on infected branches. The spores are then dispersed by the rain and wind to trees of the Prunus genus. Once the spores have landed and when moisture and temperature conditions are optimal, the spores will germinate, penetrate the branch tissue, and infection will progress as the fungus stimulates the tissue to produce the tumor-like growths. This cycle of enlargement and spore dispersal can continue for many years. As well, the infection can stress the entire tree which can cause it to weaken and exhibit symptoms of tree decline and potentially die as a result.
Pruning of infected limbs 15-20 cm below the knot, and/or cutting the infected branch off at the collar (where the branch meets the tree trunk) and then burning the infected tissue is the most effective management method for this disease. Shears and saws should be sterilized after pruning to limit disease spread to other trees of the Prunus genus. Sterilization must be done because the fungal mycelium spreads internally within the infected branch and the tools may have potentially encountered it. Pruning should be done during the dormant season when the pathogen overwinters during the winter or in early spring before fungal spores are released.

Photos of black knot disease on Chokecherry (Prunus virginiana) by Casey Howard.

In the Ecosystem

colour photo of an iron gate with a sign that says 'the poison garden'Are you looking for something scary to do this Halloween season? If you happen to be in Northern England this October, The Alnwick Garden has a small but deadly Poison Garden—filled exclusively with around 100 toxic, intoxicating, and narcotic plants. Visit if you dare! If you aren't in the area, check out this video for a little tour of the garden.

Guelph Film Festival poster.The Guelph Film Festival is kicking off its 2021 Festival on November 5th! The event takes place over 30 days, and includes 12 feature length documentaries that will be released every Friday and available for viewing for a week. There will also be over 25 short documentaries that can be viewed at any point over during the festival. The festival is a hybrid event, with some in-person screenings. If you aren't in Guelph, all films will be available for pass holders to watch across Canada! Get your pass now to experience stories from a variety of perspectives on topics like social justice, community, and the environment!

Arb Expo Virtual Walks!

Did you miss the chance to attend our Arboretum Expo staff tours? They are now available to watch for free online! Check out these videos featuring tours with past and present Arboretum staff to learn more about the plants, animals, collections, and history of The Arboretum!
screenshot of two men standing in front of a tree
Join past and present Arboretum curators, John Ambrose and Sean Fox, for a walk through the World of Trees, our gene banks, and see hidden gems along the way. Hear about the growth of these areas, adaptations over 50 years, and some of our future conservation and collection plans!
Screenshot of a video with two men standing in a field
Past and present Arboretum Interpretive Naturalists Alan Watson (also our longest-serving Arboretum Director) and Chris Earley (Interpretive Biologist) gave a tour through The Arboretum's natural spaces. They discussed how are our present-day plants, animals, and habitats different from those in the past!

Donation and Dedication Opportunities

colour photo of a forest at dawn in the fog with the words Support the Arb Give Today We are excited to share that we have a new dedicated portal for Arboretum Supporters to make direct donations!

This year we are focusing our efforts on sustainability, interpretive and wayfinding signage, and the next stages of our tree conservation work. With your help we can make our efforts go further, join our community of supporters today.


Wall-Custance Memorial Forest

Colour photo of a trail lined with memorial plaques and trees. During the pandemic, we changed the tree dedication ceremony by collaborating to create a video to continue the important tradition of remembrance. Our 2021 video shares messages from Wall-Custance Funeral Home and Chapel and The Arboretum, as well as the stories of the meaning of the Memorial Forest and ecological restorations along the Boardwalk Trail. Join us on a virtual walk through the Wall-Custance Memorial Forest grove and trail, and visit the Bur Oak planted as the 2021 dedication tree. Click here or on the image on the right to watch the video.


colour photo of a black-capped chickadee eating black oil sunflower seeds out of someone's hand. Do you have a young birder in your family? Are you looking for more ways to attract birds to your backyard? Look no further! Our Nature Break Birdfeeder Kit provides the opportunity for the young birder in your family to create their own pinecone bird feeder that will help the neighbourhood birds and create more opportunities for up-close bird observation!

Visit our Merchandise shop to check out this kit along with some other great items. Order online and have your items shipped directly to you!

Ways you can connect with The Arboretum

Make sure to keep in touch with us on social media -  follow us on FacebookTwitter, and Instagram.
Make a Donation Download & Print an Arboretum Map Think About Volunteering
email us!
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camera icon for photo creditThe header of this month's newsletter is fallen leaves from a Freeman's maple (Acer x freemanii) floating in the ephemeral pond by the Wild Goose Woods boardwalk. Photo by Sadie Campbell.