Rare coffee substitute tree species is dwindling in Ontario because of prehistoric poop

A rare tree species that was once widespread throughout North America — thanks to help from prehistoric animals — is now experiencing dwindling populations in Ontario. 

The Kentucky Coffeetree (Gymnocladus dioicus) was highlighted in a post by the City's Urban Forestry Facebook account this week, which shed light on some of the challenges associated with the large-scale dispersion of the tree's seeds. 

The species is currently at risk in Ontario and only exists in a few wild populations in the southern tip of the province. Early settlers in Kentucky would use the plant's roasted seeds to make a coffee substitute, the origin of its name. 

The plants can tolerate a range of conditions and have no serious insect or disease problems, so they're often planted along streets, parks, and yards in Toronto. 

Photo: Nikolay Kurzenko/Shutterstock. 

In its natural habitat, the tree is most commonly found in moist areas by the edges of marshes, floodplains, and forests. 

However, the species is dioecious, meaning male and female flowers grow on separate trees. To reproduce sexually with viable seeds, there need to be both male and female trees present, but there are very few natural populations in Ontario containing both types of trees. 

In prehistoric times, Kentucky coffeetree pods and seeds were adapted to being eaten by extinct mastodons, (think, slightly smaller woolly mammoth). 

Unfortunately, since modern mammals do not eat and disperse the trees' seeds, they are not as widespread as they used to be. 

Although the species can reproduce vegetatively, it usually results in poor genetic diversity among the population, so hitching a ride through waterways and human planting remain the best methods of dispersal. 

If you're interested in preserving the species, you can have one planted by the City for free on the road allowance in front of your property. While the female trees develop large pods in the fall, the City only plants the non-pod-producing male "Espresso" cultivar in residential areas.