Tuesday, March 10, 2020

Boxelder: A Tree By Any Other Name

Boxelder leaves and seeds courtesy USDAIf you know someone who goes by a slew of different names, it could be that they want to hide a bad reputation, avoid arrest, or both. In the world of trees, that individual would be the boxelder, a native member of Aceraceae, the maple family.

Boxelder is known by a dozen or more aliases, including Manitoba maple, ash-leaf maple, California maple, maple ash, sugar ash, and river maple. Because it is breakage-prone, grows fast, spreads easily, and can become a nuisance “weed” tree, its name is often preceded by a few choice words not suitable to print.

Boxelders are happiest on stream banks and flood plains, and a single-trunk specimen can grow as tall as eighty feet, with a diameter approaching three feet. The species has a shorter lifespan than its maple cousins, seldom living more than ninety years. Its weak wood and bad habit of growing as a multi-stem clump means it breaks easily and often. It apparently makes up for this character flaw by having the fastest growth rate of any maple.

Though much maligned, boxelder does have some interesting features. It is the only native maple with compound leaves, similar to those of ash. Also, it’s the sole dioecious maple, meaning there are separate male and female trees, a fact which can be used to one’s advantage, as you’ll see later. This is another similarity to ash trees, which usually observe a division of the sexes. All other maples, as is the case in the majority of tree species, are monoecious, having both male and female flowers on every tree. An interesting sidebar is that ash trees are in fact polygamo-dioecious, with males able to convert to female trees if the male: female ratio is high.

Wood-turners who make bowls and other items on a lathe are quite fond of boxelders. Its wood, which is softer and generally lighter in color as compared to other maples, often has streaks of red pigment throughout. This coloration, which is thought to be a chemical shield against decay, makes for striking and unique turned-wood creations. The irony is that boxelders are terrible at walling-off decay, something its Acer cousins do very well, though more modestly in dull hues.

Another bright side to boxelders is that their sap is laden with sugar, and they can be tapped just like sugar, red, and silver maples. One caveat (which I try to avoid because I don’t like fish eggs) is that unlike the aforementioned maples, boxelders do not yield syrup with a typical maple flavor. Having tried it one spring, I’d say it’s plenty sweet, but should be mixed with “real” maple syrup.

Historically, boxelder’s range was roughly from the Rockies east almost to the Atlantic coast, and from the Gulf of Mexico north into southern Alberta, Saskatchewan, and Manitoba. Scattered pockets were found in California, Nevada, and New Mexico.

Today its range has expanded considerably, thanks (or no thanks) to human activities. Like the rest of the maple clan, it bears copious winged “helicopter” seeds that readily blow around and take root in any disturbed soil. I read that during the housing boom after World War II, builders thought boxelders would make the fastest shade for their hasty developments. Though the trees probably were dubbed a more prosaic name like river maples, loads of them were planted in post-war tracts, thus hastening their spread.

boxelder bugI hesitate to bring up a certain downside of Manitoba maples: boxelder bugs, which adore maples, preferably boxelders. The half-inch-long black bugs with a red crosshatched pattern drink sap from maple tissues, mainly the developing seeds. If you have not seen these oval, beetle-esque lovelies, you’re fortunate. They seem to come out of nowhere in early fall to sun themselves on a south- or west-facing wall. Sometimes they end up inside, too. Luckily they’re harmless and do not breed or otherwise do unwanted things indoors. They just wander around lost until you step on them and stain the carpet.

Dealing with boxelder bugs involves a lot of caulk and a good day’s work to seal around windows, doors, and vents. It may be tedious, but I can attest that it works. A more dire approach is cut down any female boxelders you may have in the yard. Male trees are not as attractive to the bugs, most of which will fly off to nearby seed-bearing maples on someone else’s property. I’d say it’s best not to mention this strategy to your neighbors.

Photos, from above: Boxelder leaves and seeds courtesy USDA; and boxelder bug courtesy wikimedia user Bruce Marlin.

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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at PaulHetzlerNature.org or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

8 Responses

  1. I regret that you failed to mention how valuable the Box Elder is to wildlife, mainly because it holds on to its seed clusters throughout the winter, providing late-winter food to birds and squirrels when little else is available.

  2. Mike Hughes says:

    I would like to have seen better pictures with the article. After reading this piece I still would not no one if I saw it !

  3. Laurel Carroll says:

    I am an amateur mycologist (for like 25 years). I have recently noted a large (approx.4 inches across), fleshy, short-stiped, white gilled mushroom with white spores ‘fruiting’ off my elderly box elder for several years now (in the fall). Never saw this fungus before. I have encountered it in only one other place (also just recently): in the parking lot of the Middlebury, Vt., co-op, also growing on a box elder and in the fall. Trash-can group ‘Entolomatacea’? Cats broke my microscope, so can go no further with identification. Any ideas? (I live in the Ticonderoga, NY, area.) Thanks! LC

  4. Stephen Daniels says:

    As a fellow arborist, I’ve always had a certain disdain for boxelders because the trunk almost always grows at a distinct angle, making them real buggers to climb to prune or remove.

    But, I know three people who actually have a curious affinity for these rogue maples, for different reasons.

    Doug Tallamy, author of “Bringing Home Nature”, cites 285 Lepidoptera species that boxelders support, thus contributing to ecological diversity by providing food for birds and other wildlife.

    My “Plants and Design” professor at UMass Amherst, who on several occasions raved about an Acer negundo ‘Pink Flamingo’ cultiver he found at the Arnold Arboretum. A “beautiful grotesquery”, I believe was his description.

    And my ex’s father, a 1950s ESF Syracuse grad who refused to accept my description of the tree as a ” loathsome weed tree”, and who proceeded to gleefully plant dozens of the beastly trees on his property by his camp on a riverbank. May scads of boxelder bugs each year come visit him in his camp to remind him of his folly!

  5. Laurel Carroll says:

    Great trees for cats, hammocks and evening grosbeaks (they love the seeds).

  6. Anonymous says:

    The “helicopters” used to freak me out when I was a little kid. There was a box elder tree at my house in Mineville, and a couple at my grandma’s house in Westport that I wouldn’t step within 20 feet of. I’d always avert my eyes so I wouldn’t have to look at the seeds. “Regular” maples didn’t scare me, though. They had little tiny non-threatening helicopters.

  7. Carrie says:

    I’d like to try your advice about taking down our female boxelders but you didn’t mention how to differentiate them from the males. Great article…we have 5 pretty lovely, large boxelders in our yard. Ours are nicely shaped and attract so many different birds, we’re pretty happy with them. However, I’m not sure we’d ever intentionally plant these trees.