Elm leaves are doubly serrate meaning that the edge of the leaf has big teeth and the big teeth have smaller teeth. Photo credit: Ptelea, cc-by-sa 4.0

Elms are deciduous trees and many species can be found in different parts of the world. In Kentucky, we have four species of native elms – the American elm (Ulmus americana), slippery elm (U. rubra), winged elm (U. alata), and rock elm (U. thomasii). Other elms have been introduced as ornamentals and the Siberian elm (U. pumila) has escaped cultivation to become invasive.

The American elm used to be the most common elm species in Kentucky. It would grow into a large tree and was often planted along city roadways. However, American elms were decimated by an introduced fungus that resulted in a disease known as Dutch elm disease. All of our native elm species are susceptible to Dutch elm disease, but the degree of susceptibility varies by species. American elms are the most susceptible and winged elms are the least susceptible. Today, winged elm and slippery elm are the most common native elms in Kentucky.

Except for the American elm, most of our native elms are small to medium sized trees. The leaves at first look like many other generic, oval-shaped leaves. However, one good clue that you might be looking at an elm is that the leaves are doubly serrate. That simply means that the edge of the leaf has big jagged teeth like you see on the edge of a serrated knife. Then each of those big jagged teeth has smaller jagged teeth of its own. Elm leaves also tend to be rough on top. The degree of roughness varies between species with slippery elm leaves feeling almost like sandpaper on the top surface.

Elms are wind pollinated. The flowers are non-descript and bloom in the late winter or early spring before the trees begin to leaf out. Because they are wind pollinated and produce abundant amounts of pollen that floats around on the wind, elms are often a source of early spring allergies. The pollinated flowers form fruits known as samaras. Basically a samara is just a seed surrounded by a paper-like structure. The familiar maple seed helicopters are samaras; elm fruit are similar but more round.

Despite the impacts of Dutch elm disease, elms are still important components of our natural forest ecosystems. They provide food and shelter for many different species of animals. Honey bees and possibly some native bees may gather pollen from elm flowers. The ripe fruit are eaten by many species of birds, as well as, squirrels and chipmunks. Elm leaves are an important food source for the caterpillars of several species of butterflies and moths. Walking sticks and many other insects will also eat the leaves. Songbirds will nest in the tree’s branches.

This article was part of Shannon’s original Kentucky Pollinators and Backyard Wildlife blog which evolved into the blog for Backyard Ecology.

Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.

Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.