Western catalpa (Catalpa speciosa)

Nice to meet you!

I’m a deciduous tree (I lose my leaves in fall) native to North America. My name comes from the Muscogee (Creek) Nation word “kutuhlpa,” which means cigar, a reference to the shape of my fruit.

I’m fairly tall and imposing, growing as tall as 15 to 30 metres. I have a broad, rounded crown. My leaves are large and heart-shaped, giving me a charming appearance in the summer months. My foliage provides generous cover to passersby on hot summer days.

Why the greening team loves the western catalpa:

We chose this tree for its abundant flowers, which appear in spring or early summer. When in bloom, catalpas are covered with beautiful white trumpet-shaped blossoms, with purple markings and yellow spots. The flowers attract many pollinators, such as bees and butterflies, making them popular in gardens and parks.


This summer, I and the other trees in planters in the Quartier des Spectacles accomplished these feats:

  • Our transpiration helped cool the air by the equivalent of 1.30 cumulative degrees Celsius per day
  • Our leaves helped filter gaseous pollutants equivalent to a total of approximately 2.027 mg of ozone

I had a great summer in downtown Montreal! Here’s how I and the other trees in the Quartier des Spectacles spent our time:

  • We spent an average of nine hours a day contributing actively to cooling and cleaning the air
  • We rested for an average of nine hours a day
  • We spent about five hours a day in a protective mode: we closed our stomata to avoid losing any of our stored water

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.