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Canadian Urbanism Uncovered

Tree Tuesday:Black locusts announce the summer solstice

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SOLSTICE TREE WALK: MONDAY, JUNE 22, 5:30 to 7:30 pm, RARE, SACRED AND MYTHOLOGICAL TREES OF McGILL’s UPPER CAMPUS. Meet on steps of Redpath Museum. $12/$10.

The date of the summer solstice is determined by the angle of Earth when it is closest  to the sun. This year, it falls on June 21, at 9 p.m., a date and time determined by physics, not by weather, unlike the blooming times of trees. You see, I associate the blossom time of the black locust, the tree pictured above on the right, with the solstice. For the past three years, I have give an annual summer solstice tree walk and the black locust has been in bloom.

If you look carefully at the centre point of the photo above you will see a pannicle of white flowers. This, below, is what they look like up close. Gorgeous. You can see that each flower has the typical formation of a flower in the pea family which makes sense as the black locust (Robinia pseudoacacia, Robinier faux-acacia) is part of the pea family, Fabaceae, as in the French for beans, les fêvres.


When I went out hunting for a photo of the tree in flower, I thought I’d have no trouble finding one. Only last Sunday, there were fresh blooms on the black locusts that grow high on the southeast ridge of the Mount Royal Cemetery, near the Molson mausolea and not far from Camilien Houde road.

But the situation downtown was different. The colony of black locusts most familiar to me runs along Prince Arthur Street on the north side, between Clark and Ste-Famille streets. A little north of the intersection on Sr-Urbain, you’ll see the likely grandmother-grandfather (the sexes co-exist on one tree) on St-Urbain, a little north of Pr. Arthur. Its late afternoon silhouette always reminds me of the African acacia trees, St-Urbain being a bit of a savannah on this stretch.

When I arrived this morning to photograph the black locusts, there was little left of fresh blossoms; most of the blooms were dried out, either on the branch or on the sidewalk. Only this young one, an offshoot from the

p1030974roots of the elder to its right, still had fresh blooms. It also had thorns, which it typical of young black locust trees. If you’re familiar with that steep area on in the Piedmont section of Mount Royal, directly below the lookout/parking lot on Camillien Houde, you may have seen the thorns on the young colony of black locusts that thrives in this area that’s largely used for dumping snow and other urban debris. As the tree ages


it loses the thorns, presumably because it is well enough established to withstand browsing by deer, cows and sheep.

In the photo below, you can also see the delicate, leaflets that form the tree’s compound leaf. It’s a leaf that’s easy to distinguish from other trees with compound leaves, due to the elliptical shape of the leaflets and to the blue-green colour. The silhouette shows the black locust leaf in contrast to that of a Norway maple.


On the walk I’m giving this Monday, we will pass through a little known  garden that is watched over by some of the city’s oldest black locusts. Located on the upper stretch of Mountain Street, the Roslyn Robertson Herb & Scent Garden itself is planted in raised flower beds shaped like black locust leaflets in a design by landscape architect Claude Cormier. How the trees got there is a mystery to me. I’d estimate that they’re at least 100 years old and were planted when the grounds to Hosmer House, built in  1901, were landscaped.

My suspicion is that the black locust was a fashionable ornamental tree for well-to-do Montrealers. In Murray Hill Park, in Westmount, for instance, there’s a group of at least 20 black locusts of the same age as these McGill trees. Were Charles Hosmer and William Murray friends and did they share seeds or young trees? I haven’t cracked that mystery yet but I’ll let you know when I do.

I also wonder how the inner city locusts seeded themselves where they did. Generally growing in the corners of parking lots, black locusts are happy with highly compacted, low oxygen soil, as long as they’ve got plenty of sunshine. Salt doesn’t seem to bother them either, which makes sense when you consider that many wild members of the pea family grow by the seaside.

Was the seed of the first downtowner transported in the gut of some bird or squirrel? The small black seeds of the black locust have a tough exterior and need to be weakened either through nicking, perhaps by the teeth of a squirrel, or by the acid of an animal’s gut, in order to germinate. Once a first tree is established, however, the black locust is propagates via its roots and can quickly colonize an open area.

You may be wondering what the relationship is between the solstice and the black locust. In fact, there is no immediate one. There is a long pre-Christian history of celebrating the summer solstice in northern Europe where days are shortest in the winter, making the longest day — or midsommarstång, in Swedish — one of the most important celebrations. While the Swedes erect their version of the May pole — a pole and cross beam decorated with greens and two enormous wreathes of flowers — I have never heard of a particular tree associated with the ritual.

In any case, the black locust, a native of the southern Appalachians, wouldn’t have grown in Sweden until the 17th century, although it was one of the first of the New World trees to be planted in Europe. In 1601, Jean Robin, botanist to France’s Henry IV, planted seeds given him by his English colleague, John Tradescant (1570-1638), who was the naturalist for the Virginia Company. That first tree is long gone but its offshoots, planted in square René-Viviani, also in 1601, and in the Jardin des plantes, in 1636, continue to live.

Europeans took quickly to the tree, planting it especially for the flower that served both the perfume and honey industries. The prized honey is labelled as acacia honey and I found some recently imported from Slovenia.

In Hungary, the black locust is the most widely planted tree, both for its flower and its wood. Tough and rot resistant, black locust, in North America, was used for fencing, furniture, mine timbers and shipbuilding. Today, in the southeast of the United Sates, the trees are planted to remediate strip mined areas. Like all members of the pea family, black locusts can fix nitrogren through their roots and thereby enrich poor soil, paving the way for other sun-loving trees that need better soil, such as the black walnut. Sadly, a locust-boring beetle has reduced the tree’s timber value.

In Hungary, where the beetle has not yet appeared, the wood is used from everything from flooring, to furniture to wine casks and has much the same qualities as white oak but grows much more quickly.

In our patch of North America, black locusts are, at best, considered ornamental, at worst, as weeds. I’m not sure why we don’t plant them commercially for honey, either in the country or the city. Once the flowering period is over, the tree is still valuable for the fodder is provides animals and for the nitrogen it adds to the soil, not to mention its beauty.  Imagine our own Solstice brand honey: Le miel d’acacia de Montréal. Now, that would be a reason to venerate this multipurpose tree.




  1. What is a “locust” tree??? Can you also give the french name when you talk about trees? That column could be very interesting, but the fact that most of the french don’t know what you are talking about makes me just gloss over it, feeling disappointed.

  2. (Robinia pseudoacacia, Robinier faux-acacia) C’est dans le texte, il faut faire l’effort de lire…

  3. the summer solstice is when the earth is farthest from the sun, not closest. the distance earth is from the sun between the winter solstice and summer solstice has very little to do with the temperature of the earth. montreal experiences its summer in june, when the earth is farthest from the sun, because the northern hemisphere is tilted towards the sun during this time

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