When it comes to identifying a species of magnolia tree I doubt many of us would automatically reach for our trusty copy of Native Trees of Ontario as our first point of reference.
The usual members of the magnolia clan that are regularly plopped into front lawns around the neighbourhood for their giant saucers of springtime blooms are about as non-native looking as you can get. They are definitely Gone With the Wind material, something we would normally associate with images of balmy southern nights, crinoline-clad Atlanta debutante parties and, in my case, fantasies of gliding past the canopied blooms of Magnolia Lane with Arnie, Jack and Tiger in the back seat on our way to an early morning tee-off at Augusta National.
However, there is one species of magnolia called the cucumber tree (Magnolia acuminata) that is more subdued and laid back than those flamboyant southern belles, and it also happens to hold the distinction of being the only magnolia that is a native tree of Ontario.
For thousands of years, cucumber trees have withstood bone-chilling southwestern Ontario winters and actively contributed to the ecosystem of what was once our lush expanse of Carolinian forests. But their numbers rapidly diminished in the period following European settlement and now the tree is so rare and mysterious in Canada it is listed as a species at risk under the Endangered Species Act of Ontario, with only 12 naturally occurring stands growing wild in protected forest habitats in isolated areas of the Niagara region and Norfolk county.
The first blow dealt to the original cucumber tree populations in Ontario occurred when early pioneers enthusiastically began mowing down vast tracts of forested land for farming and livestock purposes. The trees’ preference for growing in rich, crop-ready soil made them an obvious target, and they were dropped with abandon to make way for expanding agricultural acreage.
As an added incentive, the wood from the felled trees, which is almost identical to yellow poplar (Tulip tree), was a valuable commodity and was regularly hauled off to the sawmill to be used as barn boards, boxes, crates and inexpensive furniture.
As expected, the widespread logging, deforestation, and loss of habitat had longer lasting and more serious implications to the survival of our native magnolia. Cucumber trees depend on cross-pollination from a nearby tree of the same species to produce seed, which makes reproduction among isolated examples difficult and unreliable. If one farmer wipes out his population and another leaves one to provide shade for his cattle, the remaining tree may be unable to receive pollen, and it will eventually die of old age without producing offspring.
Like many other primitive species of flowering plants, magnolia pollination is mainly performed by beetles. Cucumber trees have a unique way of making sure the job is done. Once the beetles chew into the cavity of unopened blossoms they are held prisoner by the slippery inside surfaces of the petals, eventually becoming covered in pollen as they bounce and fall around looking for the exit. When the flowers finally open the beetles are released and travel to a more receptive cucumber tree to deposit their pollen, completing the fertilization process.
But if there are no trees within the beetles’ range isolated plants may become self-pollinated from their own blossoms, which will often produce fruit, but the seeds that follow will not be viable.
Today there are efforts to repopulate our almost-lost native magnolia using mechanical reforestation, cultivated planting and a strict program of habitat protection in selected areas of Southern Ontario. Landowners are eligible for property tax grants in return for a promise to protect the portion of private land where stands of the trees exist, and loggers and developers can be hit with fines of up to $250,000 for destroying cucumber trees growing in the wild.
As an ornamental magnolia it can’t compete with its gaudy southern relatives, but it is an attractive tree with large oval leaves typical of the species and a pyramidal growth habit that can result in a mammoth height of 30 metres in ideal growing conditions. In spring its large greenish-yellow flowers are almost hidden among the foliage but are quickly replaced by a more noticeable display of scaly fruit that has an uncanny resemblance to small gherkin pickles – hence the name cucumber tree. And if you are lucky enough to see one in late August and early September they do put on a show – of sorts – as the small ‘cucumbers’ turn pink and then a brilliant red.
As uncommon and rare as they are for a native tree, you can occasionally see them in parks planted as cultivated specimens. One that I have seen many times is a small eight-metre 60 year-old, complete with its small red ‘gherkins’, hiding behind the west carpetbed display at Edwards Gardens in North York.
Steven Chadwick is a professional gardener and horticulturist, and long-time Beach resident