Black locust (Robinia pseudoacacia “purple robe”)

Nice to meet you!

My leaves consist of several elongated, oval leaflets. In early fall, they take on a golden yellow hue before falling. I’m a very hardy tree, so I can survive in various soil and temperature conditions. I have strong, deep roots, allowing me to withstand powerful winds and extreme weather.

Not only am I beautiful and strong, I’m useful to bees and other pollinators. My flowers are rich in nectar and an important food source for various insects.

Why the greening teams loves the black locust:

We chose it for its vibrant flowers, which come in colourful clusters, ranging from pink to purple. They can be seen all over downtown Montreal each May. Throughout the summer, when their canopy is at its densest, these trees provide much-needed shade.


Here, we measure the tree's condition to determine whether it's sleeping, doing well or in protection mode. We also measure the contribution of potted trees to air cooling and the elimination of airborne pollutants.

Help us identify our potted trees! Click here to suggest a name.


Air cooling:  

Did you know that trees transpire through their leaves? If you attach sap-flow sensors to the tree trunks, you can calculate the cooling effect of the trees. You just need to compare the surrounding temperature to the impact of the tree’s transpiration and shade. Isn’t that impressive?  

The elimination of pollutant gases: 

Trees are our best allies in the fight to eliminate pollutant gases! Thanks to sensors attached to the tree trunks, we can measure the amount of ozone that is absorbed by the leaves via their stomata (the cells that allow a plant to breathe, transpire and photosynthesize).

Why are we collecting this information?

The Quartier des Spectacles Partnership and its greening team have placed 93 trees in planters around the Quartier des Spectacles. The goal is to make downtown Montreal greener and more resilient in the face of climate change.   To optimize its greening initiatives, the Partnership is collaborating with a specialized team and various academic partners. Two research projects are currently underway, in collaboration with UQAM. One of the studies focuses on how trees cope in the high-stress conditions of a city centre, while the other explores the impact of trees on the well-being of the population.  

Click here to learn more about the research projects on the potted trees at the Quartier des Spectacles.