Tree a Week: Elm

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Characteristics and Fun Facts

  • Elms are deciduous and semi-deciduous trees comprising the flowering plant genus Ulmus in the plant family Ulmaceae and grows in variety of climatic conditions.
  • There are about 30 to 40 species of Elm
  • The elm tree originated in what is today’s central Asia spreading over most of the Northern Hemisphere.
  • Most commonly known elms are English Elm (Ulmus minor), Wych elm (Ulmus glabra), North American Elms and Chinese Elm (Ulmus Parfivolia).
  • So long as the elm does not succumb to Dutch Elm Disease (DED), a healthy elm can live to up to 400 years old. Unfortunately, for most Elms the average life span is 40-50 years.
  • Height differs based on the cultivar, though the average height is 30m with a nearly same spread. At maturity, the girth of a healthy tree measures about 1m in diameter.
  • Historically, elms have been regularly associated with death, perhaps due to their readiness to drop massive branches without warning, or due to the use of their wood for coffins.
Ulmus glabra range.svg
Distribution map
Chinese Elm is popular as a bonsai.

Dutch Elm Disease

The name “Dutch elm disease” refers to its identification in 1921 by Dutch phytopathologists Bea Schwarz and Christine Buisman. 

Due to the devastating effects of the disease in the 20th century, the English Elm is rarely found as large tree, but is more common as a shrub along hedgerows, or sometimes in woodlands.

How to detect it: Signs of Dutch elm disease come on rapidly, over about a month’s time, typically in the spring when leaves are just maturing. One or more branches will be covered in yellow, wilted leaves that soon die and fall from the tree. As time goes on, the disease spreads to other branches, eventually consuming the whole tree.

Signature DED pattern on the trunk

Read more at Gardening Know How: Dutch Elm Protection – Is There Treatment For Dutch Elm Disease  https://www.gardeningknowhow.com/ornamental/trees/elm/dutch-elm-disease.htm

With the introduction of disease-resistant species and cultivars, rapidly growing elm trees are beginning to make a comeback in recent years.

Process of disease cycle

Fungal Relationships

Morels growing near a dying elm tree in southeastern Ohio.

Elm has been associated with several fungal species, most notably the highly sought after morel mushrooms. They grow under dead elms but also under ash and apple trees.

Uses

  • Elm wood is valued for its interlocking grain, and consequent resistance to splitting, with significant uses in wagon wheel hubs, chair seats and coffins.
  • The bodies of Japanese Taiko drums are often cut from the wood of old elm trees.
  • The often long, straight, trunks were favoured as a source of timber for keels in ship construction.
The elm’s wood bends well and distorts easily making it prized by bowyers; of the ancient bows found in Europe, a large portion are elm. During the Middle Ages elm was also used to make  longbows  if yew was unavailable.
Elm wood is resistant to decay when permanently wet, and hollowed trunks were widely used as water pipes during the medieval period in Europe. And was also used as piers in the construction of the original London Bridge.

Food source: Elm bark, cut into strips and boiled, sustained much of the rural population of Norway during the great famine of 1812. The seeds are particularly nutritious, containing 45% crude protein, and less than 7% fibre by dry mass.[46]

Identification

Bark: A young Elm tree’s bark is somewhat smooth, while older trees have a rougher texture, grayish brown with irregular ridges and furrows. In some species, the furrows and ridges are very narrow.

Leaves: Elm leaf has a symmetrical base and doubly serrate margin (double-toothed) in the tips. The leaf shape is oval that tapers gradually towards the tip. The upper part of elm leaves have a rough surface, and don’t have pubescence hair. The lower part/underside of these leaves have growth of tiny and soft hair. Leaves turn golden-yellow in colour during autumn.

Flowers:

Elms have flowers that are apetalous (absence of petals) and anemophilous (pollinated by wind). Each flower is also hermaphrodite (both male and female reproductive organs are present).
Some elms bear fruit, while others are fruitless species. The fruit is a pale green achene, characterized by the presence of a round seed in the center and flattened wing on the side.

For Further Reading

If you want to know more about trees, particularly in the context of creating a forest garden, this book by Martin Crawford is worth checking out. It’s pretty affordable for a thick comprehensive book full of quality photographs and a lifetime’s worth of research and expertise from a man who has been at the forefront of forest gardening for the last 20 years.

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