Tree Tuesday/Le mardi des arbres: The Ash That No One Knows

Before I pick up where I left off in last week’s column on the subject of true members versus imposter members of the olive family, I’d like to announce that this Saturday in the abandoned Canadian Pacific railway yard, located where Henri-Julien meets the tracks, you will have the opportunity to meet most of the trees I have presented over the past six weeks, including today’s. These are all trees that have made their own way to the abandoned lot. In addition, urban flower specialist Roger Latour will introduce you to the numerous wild flowers that thrive in this urban meadow. See the end of the article for details.

Now to the ash: You may be wondering at this choice of photo. I could have picked a photo showing a complete red ash tree but I wasn’t sure of clearly capturing the leaves, the main trait that distinguishes this very common tree from all others in Montreal. The sunlit ones you see here show well the seven leaflets that comprise a single leaf (rarely, there are five) and the fact that each leaf grows directly opposite the other. This puts the ash tree, and its botanical family, the olive family, in a category that it shares with only one other major tree family: the maples.

The leaves of all other tree families — at least in the northern hemisphere — are alternate, meaning that they do not grow symmetrically on the twig. In fact, all trees in the olive family, including our common lilac, have opposite leaves. (If you read last week’s column on the Russian olive/Olivier de Bohême you will recall the discussion on why that tree isn’t a tree olive and the ash and lilac are. Classification of plants is based on the parts of the flower.)

The other thing about the ash — the red ash (frêne rouge, Fraxinus pensylvanica) — is that until very recently, it was one of the most widely planted trees by the city of Montreal. Why? Because of its ability to withstand drought and compacted soil.

This particular tree happens to be in my backyard and has considerably more soil than the trees planted in the sidewalks of such inner city streets as Roy, Drolet, Henri-Julien as well as in many parks. Being roughly 20 years old, the light brown bark has developed a tight diamond pattern and has begun to sag — or, at least, appear to sag at different points. This is typical of the red ash. The young tree, however, has a smooth and pale grey bark.

The other peculiarity of the ash is that although it can grow to a good height, the branches never grow far from the trunk, as compared, for instance, to maple or oak trees whose spread of branches reach roughly two thirds of the trees’ height. The branches of the mature ash grows away from the trunk in a gentle S shape rising slightly from the trunk and sloping down only to rise again at the end, growing, overall at an angle of 45 degrees from the trunk.

On young trees, however, the branches may arch upwards forming a narrow U around the trunk. The ash is a discreet tree, one that keeps its cards close to its chest. It’s this quality of discretion that saved the tree from the damage suffered by its confreres during the ice storm 10 years ago. Ash wood is renowned for its strength and its flexibility, which is why it is one of the most widely used woods for items as varied as snowshoes and hockey sticks, curved chairbacks and church pews.Something else to notice in the tree pictured is the absence of samaras or seed pods. This discloses the sex of this particular tree: male.

Female trees, on the other hand, are full of fruit, clusters of winged, one-seeded single samaras, as opposed to the double samara — or disamara — of the maple. Frequently, you will see dried up and blackened remains of the seed flowers. On certain male trees, you may see something that resembles a small cauliflower but in fact it’s a gall caused by a mite that has found its way into the male flower.As you will have surmised, the ash is dioecious (die-ee-shus), meaning that the male (pollen) flowers and the female (seed) flowers are found on separate trees.

This is true also of the poplar-willow family. Most trees, however, either have the flowers of both sexes on the same tree or the male (stamen) and female (pistil) parts in one “perfect” flower, as in the rose family that includes most fruit trees of the northern hemisphere.

Soon the leaves of the red ash will turn yellow and when they drop they will do so almost all at once. The leaves of the white ash, on the other hand, a species that grows in richer soils such as in pockets on Mount Royal, alongside the sugar maples, will turn a distinctive bronze-purple. In the winter, the samaras and the clusters of dried up flowers hand on the tree like strings of black and tan pearls. The whole effect is quite festive.

Despite being such a common tree and, until recently, a valuable economic tree, the ash isn’t a tree that people identify easily. Perhaps its the oblong shape of its leaflets that makes it resemble so many of the trees that grow spontaneously in alleys and in the cracks in the sidewalk, such as the Manitoba maple (also a compound leaf but with usually five leaflets) and the American and Siberian elms, both of whom have simple sharply toothed leaves. But now you know how to distinguish the ash’s compound leaves from those of its streetmates.

This Saturday marks the first in a series of tree walks that I am giving throughout the fall. Meeting place: south end of the Canadian Pacific field on Henri-Julien, across from the Carmelite Monastery.Time: 12h = 14hCost: $10 Information: 514-284-7384, bronwynchester@gmail.comFor other upcoming tree walks, see: www.foretmontreal.com.