and Deciduous Forest Trees
of Southern Ontario

White Elm
Ulmus Americana

Location in Ontario: White Elm trees grow throughout the Deciduous Forest Region, and further north.

Magnificent White Elm, Essex County

Genus Ulmus: The leaves of Elm are asymmetrical. The overall form of Elm trees is an umbrella shape, White Elm with the most pronounced. Elms are monoecious with perfect flowers in dense clusters. They appear in very early spring. Seeds are nutlets contained within a thin wing (samara). Nutlets are deeply notched and fall off in May. In Ontario, this genus includes Rock, Slippery and White Elm.

Dutch Elm Disease was accidentally brought to Canada in 1944, via wooden crates. White Elm are the most affected by the disease. Once a tree is infected, nothing can be done. Preventative pesticides can be used but are costly. Development of a disease resistant hybrid has been unsuccessful. White Elm trees once lined many streets in Southern Ontario. Today, only a few stately Elms can still be spotted, indicating some immunity to the disease. Elm trees produce abundant seeds every year, and the seeds easily germinate. This has helped Elm to survive Dutch Elm Disease.
Dutch Elm Disease History  

Habitat: Today, due to Dutch Elm Disease, White Elm is mostly an understorey tree that grows on wet but well drained soil or sand.

Landscape Use: If an Elm tree is planted, care must be taken to avoid Dutch Elm Disease. White Elm is a fast-growing but large tree with an umbrella shape that provides deep shade.

A group of White Elm in winter, Norfolk County

Leaves: White Elm leaves are simple, with double teeth. The leaves are asymmetrical. Leaves decompose rapidly and have a relatively high content of potassium and also of calcium.

FALL COLOUR WATCH: yellow to brown 

White Elm starting to turn colour, Norfolk County

Flowers: White Elm is monoecious with perfect flowers. Elm flowers are tiny and light coloured, and found in dense clusters. They appear in very early spring.

Fruit: White Elm seeds are deeply notched nutlets contained within a thin wing (samara). Fruit ripens quickly after pollination. White Elm produces fruit after 15 to 40 years of growth with bumper crops of seeds every 1 to 3 years.

Bark: The bark is mottled gray and scaly. The branches are arched and "weeping" downward, giving an overall umbrella-shaped form.

Size: White Elm is one of Ontario's largest trees, reaching 35 metres and living to 200 years of age.

Wood: Elm wood is hard and heavy. White Elm has a beautiful double grain. Due to its hardness, Elm was favoured for wheels, hockey sticks and boat frames.
Specific gravity: 0.64
Janka Hardness:
830 lb
Wood Comparison Chart

Genetics:  White Elm is tetraploid with 56 chromosomes, while all other species of Ulmus are diploid, with 28 chromosomes. Because of this, hybridization of White Elm with other Ulmus species is mostly unsuccessful. This has resulted in little success with finding a hybrid which is resistant to Dutch Elm Disease.   

Side by side young White Elms, Norfolk County