Blog written by AmeriCorps service member Esmeralda Figueras
Here in Nashville, this American Elm is one of five elm species native to the area. American Elms were once a popular choice for street trees because their long, graceful branches formed vaulted arches, cathedral-like, over whatever path they lined. In the 20th century, American Elms were decimated by disease, but new disease-resistant cultivars allow us to enjoy these stately trees once again.
Identifying the American Elm
Elm trees tend to have a narrow branching pattern; that is, their branches go up more than out, and they form a very narrow “V” shape where they meet the trunk. This vase shape is distinctive, and can be an easy way – even from a distance! – to identify an elm.
Elms also have finely-toothed, alternately arranged leaves. Native species of elm all have grayish, deeply furrowed bark (unlike the nonnative Lacebark Elm — another popularly planted elm tree in Nashville). If the leaves are 3-5 inches long and have lopsided, asymmetrical bases, it’s probably an American Elm.
Samaras and Songbirds
Elm trees don’t produce any nuts or bulky fruits, only papery thin samaras. But don’t be fooled – this tree brings all the birds to the yard! Goldfinches, Purple Finches, Rose-Breasted Grosbeaks, Turkeys, Wood Ducks, and a host of other birds all eat the samaras, as do mammals like chipmunks and possums. Other birds, such as warblers and woodpeckers, are attracted to the native insects that elms house. One mature American Elm can reportedly feed dozens if not hundreds of migrating birds.
Dutch Elm Disease — Lessons Learned
As mentioned, Elms were once ubiquitous street trees in cities across North America and Europe. They were a functional choice of tree as well as a beautiful one – not only do they tolerate a wide variety of planting sites, but in addition, their naturally high arching branches stay out of roadways with minimal pruning.
Everything changed after the introduction of the deadly Dutch Elm Disease (DED). First identified in the Netherlands in the 1910s, DED is a fungus accidentally introduced from Asia. It was easily transmitted from root to root among closely planted street trees. Its spread in the US was further exacerbated by two other invasive species: the smaller European elm bark beetle, and the banded elm bark beetle. Dutch Elm Disease killed an estimated 100 million trees in Europe and North America. The northeast and Great Lakes region were especially hard hit; by 1982, Toronto had lost 80% of its 35,000 elms. The loss of life in wild populations is difficult to quantify.
In the century since the introduction of these invasive species, botanists and mycologists have identified survivors and bred them to create disease-resistant cultivars of American Elms. They’ve also created hybrid species by crossing North American elm species with Asian ones (which have had millions of years to naturally develop disease resistance to DED and related fungal diseases). Arborists have also learned how to treat elms with early stages of DED.
The other thing we’ve learned since the DED pandemic first began is the importance of biodiversity. Tennessee wasn’t particularly hard hit by Dutch Elm Disease; a local arborist said he sees maybe 4 cases a year, and you can still see majestic old elms in the Vanderbilt Arboretum. Nevertheless, one never knows when another epidemic will start, which is why it’s best to always plant multiple species, rather than to put all your eggs in one basket. The Cumberland River Compact typically offers 10 tree species each planting season (5 in fall, and 5 in winter), and mixes up those 10 options every planting season, and about 250 tree species or cultivars have been planted in the Root Nashville campaign so far.
Because of DED, American Elms are federally listed as endangered. You can help repopulate them and support wildlife by planting disease resistant cultivars in your garden.
Planting
This hardy, fast growing shade tree is a beautiful addition to any landscape. American Elms can weather long, hot summers and harsh, cold winters; they tolerate drought and urban stressors like pollution with remarkable grace. They prefer low-lying moist settings, but they’ll grow in a wide range of soils. It’s best to plant them where they’ll get full sun and good air circulation.
In autumn, they have golden foliage. American Elms grow to be about 60-80 feet at maturity, with a crown 40-50 feet wide.
Want to keep learning about Elms? Check out this blog post from our friends at the Nashville Tree Conservation Corps.
Elms coming to a neighborhood near you
These valuable overstory trees are a popular landscaping choice and native to the area, so be on the lookout for them in your neck of the woods! Learn how to get an Elm of your own through our Neighborhood Planting Captain program, or reach out to hello@rootnashville.org to put your name on the waitlist for more free tree opportunities.
All newly planted trees, regardless of what species they are or who plants them, can be counted towards the citywide goal of planting 500,000 trees by 2050! Planting season begins in mid-October, and ends in April (excluding bare root trees and some container trees, which have an extended timeframe).
