The RED MAPLE
Peter Duinker, Halifax Tree Project
2020-08-31
The red maple (Acer rubrum L.) is the fourth maple species to be featured in this series on the street trees of Halifax, after Norway maple, sugar maple, and silver maple. Yet to come, our last of twenty species, is the Freeman maple.
Red maple has the largest north-to-south range of any eastern-North-American broadleaved deciduous tree species. It occurs naturally in southern Florida all the way to Newfoundland, from the Atlantic to beyond the Mississippi River. It co-occurs with other tree species in 87 of the 88 vegetation types we have in Nova Scotia, often found in all the forest plots measured to characterize the veg types of the Forest Ecosystem Classification of Nova Scotia. I would hazard a guess that red maple is the most common broadleaf tree species in our province. It grows on an amazingly broad diversity of sites.
Red maple is called red maple because so many of its parts are red. Most people know that its leaves turn red (and sometimes orange) in the autumn. Also, though, its buds, flowers, and fruits (the samaras) have red colouring.
I find it difficult to identify what features make red maple special for the street environment. Perhaps its lack of redeeming features plus its ubiquity in the woods of Nova Scotia are why it has not risen to anywhere near the top of past planting lists for Halifax streets (it is, after all, the 15th most abundant tree in our streets, according to our research data on mature street trees). I’m glad to see it featured more strongly in current planting lists for it adds wonderful indigenous diversity to the streetscape ecosystems of the city.
Red maple is kind of a middle-of-the-pack species for me. It is a mid-tolerant species, meaning it can tolerate some competition for light and nutrients when it is young and under a canopy of mature trees. It can reproduce readily from both seed and stump sprouts - when you see a red maple tree with multiple trunks coming from the same base at ground level, that was doubtless a stump-sprout regeneration event (check these out in Point Pleasant Park).
Red maple is neither the strongest tree in the street nor the weakest. Indeed, in cultivars where red maple is crossed with silver maple to create Freeman maple (more on that in about five weeks), the red maple imparts a stronger wood to the cultivar than does the silver. Red maple grows fairly fast and is reasonably resilient in the harsh street environment. It is neither the longest-lived tree among street-tree species nor the shortest. It is neither the largest nor the smallest at maturity. Red maple is relatively free of life-threatening pests and diseases.
Red maple wood does not seem to be distinguished for specialty products in wood-based industries. I’m not averse to it in my firewood piles, but it is not as dense as, say, sugar maple, red oak, and yellow birch, so it gives less heat per unit volume than these other species.
Red maple is relatively easy to identify. The leaf is the main giveaway - it has 3 to 5 main lobes with shallow indents and the margin is sharply toothed or serrated (see image above). Its bark is very much like that of sugar maple - smooth and grey when young, irregularly furrowed and plated when mature. The leaves are not particularly large, especially when compared with those of the sycamore maple.
Before finishing this article, let’s review the Acer (maple) genus in Canada and Halifax. There are more than a hundred maple species worldwide, and Canada is a native home to ten of them. Four are native to Nova Scotia - sugar, red, mountain (A. spicatum), and striped (A. pensylvanicum) maple. Mountain and striped maples are small at maturity and I’ve never seen them planted as a street tree (but you can find them in the woods in and around the city). In Halifax, we have several other species of maple in the streets: Norway, silver, sycamore (A. pseudoplatanus - not too common), field (A. campestre - I’ve only seen one), paperbark (A. griseum - also rare), and Freeman (A. x freemanii). Japanese maple (A. palmatum) is common around the city in front and back yards but it is not planted streetside.
My arsenal of red-maple photos is virtually non-existent, so what are presented here are pictures I found online. And because I am in self-isolation following travel outside the Atlantic region, I am unable to wander the streets and take some photos of red maple for this article. My apologies for that.