A native Ontario tree is poised to make a huge comeback on Western grounds.
A new set of pawpaw (Asimina triloba) trees have been planted on UC Hill near the Physics and Astronomy Building recently, in the hopes of increasing the campus’s biodiversity and promoting a healthier natural ecosystem.
“The addition of the new trees will support the others that are already on campus,” said Mike Lunau, landscape services manager at Western. “They are important to increase the biodiversity on campus, producing edible fruits.”
The five pawpaws planted this past summer, each measuring about a metre in height, add to the unnumbered pawpaw trees already growing on campus, mostly in the Middlesex College area.
With flavour as rich as its history, pawpaws were once cultivated by Indigenous Peoples and largely grew in the Carolinian forest zone in Southwestern Ontario. Their significance is more than just aesthetics; its history is tied to the land where Western now sits.
“Pawpaw is unique to where we are in southern Ontario. This is a region known as the Carolinian life zone. We have more species biodiversity where we are than anywhere else in Canada and the pawpaw was unique to our region,” explained Brendon Samuels, a PhD student at Western involved in avian research with a keen personal interest in the pawpaw plant.
Centuries ago, pawpaw was an important staple for Indigenous Peoples in southern Ontario, who planted them in abundance near their communities. As more agricultural lands were developed, the number of pawpaws growing in the region dwindled. Currently, the rare species is ranked N3 (vulnerable) in Canada by Nature Serve Explorer, a not-for-profit group of scientists collecting data on species to guide decision-making on conservation efforts.
Although its decline in the region has been a great concern, the pawpaw is seeing a resurgence, as ecologists and historians advocate to revive the native species by encouraging communities to plant them.
This gives nature advocates like Samuels – who planted pawpaw seeds in pots last year and has since given away many of the seedlings – hope that the once sprawling species will retake its rightful spot in the region’s natural ecosystem.
“I think it’s really beneficial to have native plants like this be featured so prominently at the centre of our campus because it serves a really important public education purpose,” he said.
Ecosystem of life
Part of the appeal of the pawpaw is its sweet-tasting fruit, which takes several years to produce. The tree is also unique in that it is not self-fertile, meaning it requires pollen from another pawpaw flower to produce fruit. Many fruit trees can produce fruits by self-pollination, using pollen from one flower to pollinate another flower of the same tree. It’s why pawpaws are typically planted in pairs or multiples.
Pawpaws are also not pollinated by bees but by beetles and flies, which makes cultivating them in abundance even more significant for biodiversity.
“A lot of people don’t realize just how bad things have become for insects,” said Samuels. “The crops we grow to eat depend on insects in the wild to pollinate those crops. But there’s also tons of animals that are at risk that depend on insects as part of their lifecycle.”
Planting native species, such as pawpaws, near communities where people live will help restore insect habitats that are vital to biodiversity, he added.
As stewards of the campus landscape, Western’s landscape services plants about 200 Carolinian or native trees on campus each year. The pawpaws were among 203 trees planted this year, including bitternut, black gum and others.
Enriching plant biodiversity across campus is part of Western’s commitment to sustainability outlined in its new strategic plan. Western is also home to thousands of tree species and has been officially designated as an arboretum.