Home & Garden Columns

Storied American Elms Vanish from Field and City

By Ron Sullivan, Special to the Planet
Tuesday September 19, 2006

By Ron Sullivan 

Special to the Planet 


A reader wrote to ask me to discuss the sad state of the elm species. Since threatened trees are much in the news locally, and have deserved even more attention than they’ve had, I’m glad (for fairly scratchy values of “glad”) to mention this, one of the native American marvels whose destruction has been so thorough and so forgotten that we’re generally oblivious to our own impoverishment.  

The first species to die off in such devastating fashion was the American chestnut. That was a keystone species of the eastern forests, and when chestnut blight did it in so completely, the whole flora and fauna changed. Oaks took over the niche, but acorns and chestnuts aren’t quite the same, and dependent populations shifted or vanished in the interim between die-off and replacement.  

The blight that struck American elms, starting around the 1930s, had had as much effect on the ecology of cities as on forests.  

Elms, particularly Ulnus americana, had long been the mark and pride of civilization. Their great size in maturity and their regal vase-like form made them logical as landmarks and meeting places long before streets and buildings cluttered up the early transit hubs—river fords, trail crossings, routes between settlements—and newcomers followed the examples of the first residents in revering the tree. It was a short step between founding a town around a distinctive tree and planting the town’s streets and squares with its descendents and brethren.  

One of my favorite tree plantings ever was a great double row of elms on Market Street, one of the main thoroughfares of Harrisburg, Pa. It was a sylvan feeling, indeed, that the great trees conferred on the street—three broad traffic lanes plus parking, roughly as broad as Berkeley’s University Avenue—as they arched almost all the way across the pavement, up the hill past my high school. They were especially breathtaking in autumn, when they turned brilliant gold. 

It’s been decades since I saw the elms last—most of my family moved to Florida, so we meet there—and I haven’t had the heart to ask if they’re still alive. Certainly they were senior trees when I left, 33 years ago.  

Dutch elm disease is a fungus, variously called Ceratocystis ulmi or Ophiostoma novo-ulmi or Ophiostoma ulmi, that clogs the tree’s vascular system; the leaves wilt and die because the water from the roots can’t get to them, and the whole tree follows. The fungus evidently got here from Europe, where it was ravaging elms, in a shipment of veneer lumber. It’s spread by two beetle species, the native bark beetle Hylurgopinus rufipes and the European elm bark beetle, Scolytus multistriatus, and directly from tree to tree when roots meet and “graft” to each other, as many kinds of tree roots commonly do.  

One thing that accelerated the epidemic in cities was precisely the strategem that planners and landscapers had used to get that stately allee effect: effectively, they’d planted a monoculture. Individual elms and regional varieties might have more resistance to the fungus, but all these close cousins—even seed-grown trees in the nurseries were likely to be from seeds of one or a few selected handsome or historic trees—didn’t stand a chance.  

American elms were even less resistant to the new fungus than European elms had been; no surprise, in a completely unexposed population. Humans have experienced similar disasters.  

Arboreta and laboratories have been working for decades to breed fungus-proof American-type elms, using parents from different populations or hybridizing American elms with Siberian elms and other related species. 

We have quite a few Chinese elms, Ulmus parvifolia, also used in this effort, as street trees in Berkeley. I like those; they’re graceful and have interesting bark patterns (“lacebark elm” is an alternate name) and are easier to prune than you might suppose if you look just at some of our more grotesquely handled specimens.  

But they’re not the same sort of tree as American elm. (Not to be all parochial about it: Other North American elms like the wahoo and the slippery elm, while also nifty in their own right, aren’t in the same league either.)  

Replacement plantings have carried their own problems; many, like fruitless mulberry, are ridiculously allergenic. None has quite the place in history as American elm, and we’re poorer for having lost so much of the species.  


Photograph by Ron Sullivan.  

This Chinese elm is a bit mopheaded; careful thinning would improve its looks. The species resists Dutch elm disease, but doesn’t fill the grand-old-tree niche of American elm.