Elm is one of the most common trees, found around the world in different varieties and is perfect for providing shade in the garden and along neighborhood streets. There are more than 30 species, but most share the same characteristics: serrated green leaves that turn yellow in autumn, very wrinkled gray-brown bark, and a roughly vase-like shape of the tree that makes it distinguishable from other plants. Unfortunately, graphiosis threatens many old specimens; however, the presence of this disease can be used to identify elms.
Steps
Method 1 of 3: Recognizing Elms by Basic Characteristics
Step 1. Look at the leaves
Those of the elm are arranged alternately along the two sides of the stems and are ovoid with the pointed end; the margins are serrated and the veins very evident, while at the base they are slightly asymmetrical. Many varieties have leaves with a smooth upper surface and a velvety lower one.
- For example, the leaves of the American elm are typically 10-15cm long.
- Those of the ciliated elm, present in the humid woods of northern Italy, have leaves that are no more than 10 cm long with unbranched ribs.
- The field elm has elliptical leaves about 5 cm long and 3 cm wide, they are green on the upper face, while the lower one is gray-green.
Step 2. Inspect the cortex
That of the elm is very rough and with several veins that intersect each other. The color varies from a light gray to a dark greyish brown and the surface is deeply wrinkled.
- The Siberian elm is an exception because it often has a green or orange colored exfoliated bark.
- That of the ciliated elm, unlike other species, remains smooth even when the tree reaches maturity.
- That of Ulmus crassifolia has a lighter gray-purple hue than that of other varieties.
Step 3. Check the total size of the shaft
A mature elm reaches 35 m in height and with a trunk diameter of 175 cm. The width of the foliage can reach 9-18 m depending on the variety and the cultivar. For example, many species present in America can become even larger, reach a height of up to 39 m and branches that extend for up to 37 m.
The elm takes on a "fountain" or "vase" shape
Step 4. Pay attention to the trunk
The one of these trees is generally branched, in fact there could be two or more branches that develop from the central trunk; if you see a tree with only one central vertical trunk, it is not an elm.
Step 5. Evaluate where the plant is located
Use this information to figure out if you are facing an elm. Different varieties grow in different places; for example, the American one is more widespread in the eastern states of the USA, from the rocky mountains to the east. The ciliated elm is present in the northern and central Italian regions, while the canescent elm is widespread in the southern ones.
- The Siberian elm (Ulmus pumila) is common in Central Asia, Mongolia, China, Siberia, India and Korea.
- The field elm is widespread throughout Mediterranean Europe and also in Mediterranean Asia. For some decades the graphiosis has been decimating the old specimens and the greatest concentration of these is found in Portugal, France, Spain and England; however, scientific research has made it possible to develop a variety of elms which show resistance to this disease.
- If you know that the area you are in is full of elms and the description matches this tree, you can be sure that it is indeed an elm; do your research in an area where this plant is likely to be encountered.
- Elms adapt to different climates and environments, even poor and slightly salty soils, extreme cold, atmospheric pollution and drought; however, they prefer areas exposed to full sun or partially shaded and moist but well-draining soils.
Method 2 of 3: Observe the Tree Carefully
Step 1. Recognize the creatures attracted to the plant
There are many animals, insects and birds that share the ecosystem with elms. For example, the American one attracts birds and mammals (mice, squirrels, possums) that feed on the insects that live on the tree; deer and rabbits gnaw the bark and small branches of young specimens. If you notice animals and insects around the tree, it could be an elm.
- You can see the caterpillars eating its leaves.
- It is not uncommon to encounter woodpeckers, squirrels and tits coexisting with this tree.
- The red elm attracts birds that feed on its fruits and pests.
Step 2. Look for visible roots
The base of the trunk is reinforced by a shallow, visible and widely branched root system. The bark is generally similar in color and texture to that of the rest of the plant. Although the root system is not always present in young specimens, look for it on the surface of the soil around the trunk.
Step 3. Look for diseased trees
Elms are commonly afflicted with graphiosis; if you come across a plant that shows symptoms of such mycosis, you can confidently establish that it is an elm. Here's what to look out for:
- Dead leaves that have not fallen from the tree;
- Yellowing or other discolouration in the fall or spring
- Compresence of withered leaves and buds.
Method 3 of 3: Recognizing Seasonal Changes in Elms
Step 1. Look at the flowers
Depending on the species, you may or may not notice the presence of flowers in spring; for example, the ciliated elm produces small purple flowers in early spring. The mountain one blooms in a similar way, even if the inflorescence has a color that tends more to reddish.
- The Caucasian elm, on the other hand, has small green flowers that appear in spring.
- Field elm develops small red flowers that appear in clusters in early spring.
- The inflorescences can remain hidden by the leaves, if these are already present; you must therefore pay close attention to identify them and decide whether or not you are observing an elm.
Step 2. Inspect the seeds
They form and fall from trees in spring, immediately after flowering, and have a peculiar appearance: they are round, flat and covered with a paper-like shell.
- Most trees produce individual seeds that are the size of a pea.
- The seeds are enclosed in a thin, oval green shell that is shaped like insect wings and is called a samara.
- When they reach maturity, the seeds change color from green to yellowish-brown or taking on a hay-like hue.
Step 3. Examine the elms in the fall
Observe them when the leaves are changing color; in many species these become bright yellow and in some cases even purplish. For example, those of ciliated and mountain elms take on a deep yellow color during autumn. The leaves often hide the flowers that are present even in late summer, so be very careful while evaluating whether or not the plant is an elm.
Step 4. Observe it in winter
It is a deciduous tree, which means that it sheds its leaves once a year starting in autumn. During the winter it is bare and in the spring the new foliage begins to form; if you notice this feature, it could be an elm.
Advice
- Do some research online to look at pictures of the different elm varieties, so that you have some visual references when observing outdoors. Perhaps you can also find an application to download on your mobile that you can use as a database to consult.
- Elms are susceptible to many diseases, including graphiosis (a fungal infection spread by insects). You can recognize a diseased tree by withered shoots or leaves and large patches of dead or yellowing leaves, which form even when the tree is young and the season does not justify the change in color.
