Self-Guided Tour: May 2025
Canada’s Carolinian Zone & Beyond
Contributor: Lyn Anderson, VanDusen Volunteer Guide
This month’s tour of VanDusen Botanical Garden focuses on plants native to Canada’s Carolinian Zone in Southern Ontario. This zone is surrounded by the Great Lakes, from Grand Bend on Lake Huron to Toronto on Lake Ontario. It is home to the largest number of native species of any region in Canada. These same species are found in North and South Carolina; our tour showcases a few of them.
Upon entering the plaza, facing Livingstone Lake, turn right and follow the arrows to the Eastern North America sign.
1 – Largeleaf cucumber tree (Magnolia macrophylla), native to the Southeastern United States. This species has the largest leaves of any deciduous tree in North America, reaching 80 cm (nearly 32 inches). Its snow-white blossoms are dinner plate size. Fruit is long and cucumber shaped. The Magnolia Family (Magnoliaceae) is ancient, dating back 95 million years ago (mya). Members of the Magnolia Family have widespread but fragmented ranges, because they have survived many geological events such as the ice age. The genus Magnolia was named for Pierre Magnol (1638 – 1715) director of Royal Botanic Garden in Montpellier and one of the first botanists to classify plant families.
The cucumber tree (Magnolia acuminata), found in VanDusen’s Canadian Heritage Garden, is Canada’s only native magnolia. It has smaller leaves and blossoms have a yellowish green tinge. Brooklyn Botanic Garden has bred several yellow hybrid magnolias using Magnolia acuminata as one of the parents. One such hybrid is 2 – Magnolia x brooklynensis ‘Elizabeth’.
3 – Pawpaw (Asimina triloba). It is the only temperate member of the mostly tropical and subtropical Custard- Apple Family (Annonaceae). The fruit has a soft texture, like banana, and can weigh just over 500 g (1 pound). It is brownish yellow and ripens quickly making it unsuitable for shipping to your local grocery store. The flowers are a beautiful rich purple colour. Our tree is young, however UBC Botanical Garden has a more mature tree that is in bloom during the month of May.
4 – Tulip tree (Liriodendron tulipifera). The Magnolia Family has two known genera: Magnolia and Liriodendron. The ancestors of Liriodendron evolved before bees and like magnolia species are pollinated by beetles. The emerging flowers are large yellow tulip shaped and are hard to see due to the height of the tree. Continue to down the dirt path until you reach the pavement. Stop and look across to the bench. Next to it is Magnolia ‘Yellow Bird’, another hybrid from Brooklyn Botanic Garden. Turn right and follow the curved paved path until you reach the wooden bridge.
5 – Joe-pye weed (Eutrochium maculatum). The name is attributed to Joseph Shauquethqueat, a well-respected Muhhekunneuw (Mohican) sachem (leader) known as Joe Pye during the 18th and early 19th century. Today it makes a dramatic addition to any garden and attracts moths, butterflies and honeybees.
6 – Kentucky coffeetree (Gymnocladus dioicus). Gymnocladus comes from the Greek words for ‘naked branch’. The large bipinnate leaves are late to sprout in the spring and fall early in the autumn, leaving the tree bare for a good part of the year. The pods may have evolved to be disbursed by megafauna that are now extinct; this may help explain the limited range of this tree today. The seeds in the long brown woody pods contain a toxic alkaloid, cytisine, which is poisonous to most animals and birds. Cytisine is degraded by roasting, which enabled early settlers to use the beans to make a coffee substitute, hence its common name.
7 – Mayapple or American mandrake (Podophyllum peltatum) bears a small white flower on a single elongated erect stem under its umbrella shaped leaves in April. The small lemon shaped ‘apple’ starts to appear in May and matures into a fleshy golden yellow fruit in the summer. They are easy to spot in the fall when the plant is dormant, and the leaves die back. It is edible and tastes like passion fruit. All parts of the plant except the fruit are poisonous, so caution is paramount.
8 – eastern white pine (Pinus strobus). Look up to take in the tree’s feathery appearance. Needles are long and slender, in bundles of five reaching up to 15cm (six inches) in length. It is the provincial tree of Ontario and the only pine species native to the Carolinian Zone of Canada. In Britain it is known as Weymouth pine named after George Weymouth, a British naval captain who took seeds back to England in the early 1600s. Back in America the British also called it the mast pine due to its very tall straight trunks. It was logged extensively; ships were purpose-built to carry huge loads of logs back to England to use as masts.
9 – ostrich fern (Matteuccia struthiopteris) is nativefrom Alaska, through Canada and Eastern USA. The fronds resemble ostrich feathers once they unfurl. The genus is named for Carlo Matteucci, a 19th century Italian physicist. This fern is a source of edible fiddleheads, considered a delicacy, which must be harvested as the tightly wound fronds first emerge in early April. They are said to taste like asparagus with a “hint of soil” and are a popular wild foraged vegetable in eastern North America.
10 – white sassafras (Sassafras albidum). The chemical safrole which gave root beer and sarsaparilla its distinctive flavour was deemed carcinogenic and banned in 1960 by the American FDA. Modern day root beer is now made with such plants as wintergreen. Being dioecious, male, and female flowers develop on separate trees. Small yellow flowers appear in spring along with polymorphic leaves that can be three-lobed, bilobed (mitten shaped) or unlobed (oval shaped). The population of this tree is depleted as it was heavily harvested by early settlers who thought root bark used for medicine was a cure-all. It was also the second most exported North American plant to Europe, after tobacco. Our tree is young – planted in 2016. There two other trees in the Canadian Heritage Garden.
11 – white wakerobin (Trillium grandiflorum) a beautiful spring ephemeral with its three-petalled white flowers that bloom in early spring and go dormant by midsummer. Another ephemeral in this area is 12 – red trillium or stinking Benjamin (Trillium erectum). If successfully pollinated, its dark red petals die back leaving a red berry-like capsule.
13 – bald cypress (Taxodium distichum) a unique member of the Cypress Family (Cupressaceae). It differs from the coast redwood and the giant sequoiain afew ways. It is native to Louisiana and Florida, rather than California, it is deciduous and has ‘knees’, which are woody projections that grow from its roots. These knees are evident at the base of the trees and in the water in front of you. Although no one has been able to determine the exact function of the knees, some people think they may help with root aeration, storage of nutrients, or provide stability in the soft mud and water in their natural habitat. You can get an idea of their strength where they have pushed through the asphalt pathway on the other side of the pond.
14 – dawn redwood (Metasequoia glyptostroboides), once known only from fossils and thought to be extinct until a grove of them was found in China during the second world war. Fossil evidence suggest that Metasequoia was common across the Northern Hemisphere in the late Cretaceous (100 million years ago). Like the bald cypress it is deciduous.
Leave the Eastern North American collection and head west down the path through a small grove of 15 – coast redwood (Sequoia sempervirens). Redwoods are monoecious meaning ‘one house’ in that seed cones and pollen cones are on one tree. The coast redwood also reproduces via root sprouts, which can grow on burls, around the base of parent trees or on fallen trees and branches. Coast redwoods are native to the north Californian coast and southwest corner of Oregon. They need fog and rainfall to thrive whereas giant sequoias (Sequoiadendron giganteum) are happy in their dry Sierra Nevada terrain.
Continue along until you reach the main paved pathway, turn right, then left. Ahead on your right are four 16 – hybrid white flowering dogwood (Cornus ‘Eddie’s White Wonder’) bred by British Columbia nurseryman and rosarian Henry Matheson Eddie (1882 – 1953) during the 1930s and 1940s. Here east meets west: They are a cross between the eastern flowering dogwood (Cornus florida) and our BC native Pacific dogwood (Cornus nuttallii). This cultivar has big, bright white flower bracts and disease resistance to dogwood anthracnose.
Return to the Plaza or continue down the path to enjoy the colourful wonders the month of May brings to VanDusen Botanical Garden. We hope you will visit often as each day brings something new to enjoy.
