Species of the Month, October 2022: Paw Paw (Asimina triloba)
By: Brianne Curry
The pawpaw is a small tree or tall shrub (growing to about 10 m tall) which is native to Carolinian forests in southern Ontario, and produces edible fruit. The large fruit are about the size of a mango, but the flavour is more like a banana-mango-custard.
This little-known but ‘gaining-in-popularity’ tree has a fascinating history…and might just play a big role in restoration.
- Size: Smaller tree, only growing to about 10 m tall
- Appearance: Leaves are large and smooth, growing up to 30 cm long, and turning rich golden yellow in autumn
- Fruit: Oblong, yellowish-green and maturing to darker brown, with soft creamy sweet custard-tasting yellow flesh, and black seeds.
- Habitat: Prefers moist to wet, rich loamy soils, and full to part shade
The name ‘Paw Paw’ was first given to the tree in the 1500s. Centuries ago, the pawpaw fruit was cultivated by indigenous peoples in southern Ontario as an important food source. The bark of the tree was also used as a fiber source. However, as agricultural lands were established in the region, the population of pawpaws declined. Now, the pawpaw is listed as a vulnerable species in Ontario according to Nature Serve Explorer.
The pawpaw is enjoying a bit of a resurgence, as indigenous peoples, ecologists and native plant enthusiasts are advocating for planting pawpaw in both natural and cultivated areas. Several conservation groups are directly involved in procuring and distributing pawpaw trees across southern Ontario, and native plant nurseries are increasingly growing this unique species for sale.
The pawpaw tree requires a partner or pair in order to be pollinated and produce fruit. Unlike domestic fruit trees like apples, the somewhat unpleasant smelling pawpaw flowers are actually pollinated by beetles and flies, not bees. This is part of what can make them difficult to cultivate, and difficult to drastically increase their population. For home gardeners, pollination is sometimes easier done by using a paintbrush, though theories are still being developed about the best way to encourage pollination, which sometimes includes recommendations for things like hanging meat near the flower!
The unique beetles that pollinate pawpaws, as well as the insects that rely on the pawpaw as a host plant (such as the Zebra Swallowtail Butterfly) also in turn provide food sources for other species like birds, so integrating the pawpaw in restoration efforts in natural areas and in landscaping projects can play an important role in restoring insect and wildlife populations in the Carolinian zone, and contributing to enhanced biodiversity.