Ulmus americana

American elm ( Ulmus americana)

The American elm ( Ulmus americana) belongs to the family Ulmaceae and was in former times the territory of the Eastern States and in the northern and midwestern United States and widespread. Even today, many trees lining the streets. However, the stocks due to a fungus ( Ceratocytis ulmi ) were decimated in the second half of the 20th century.

The American elm tree reaches a height of about 40 meters. The adult tree - it can be around 300 years old - is different from the other elm species including through the growing pattern that looks like an inverted pyramid. The crown diameter to be about 30 meters. The tree grows very fast, the first seeds develop but only at the age of 30 to 40 years. The seeds, which are formed depending on the climatic region in April or May, germinate immediately on the first floor.

The American elm preferred swampy or wet areas, flooding up to 100 days a year do not mind. Replanting is carried out not only for aesthetic reasons. At the same time the tree yields valuable timber, which is characterized by toughness and durability. At the same time, the wood on a nice grain for furniture making. The Native Americans used some of the bark for making canoes, ropes and other artefacts.

The above mushroom Ceratocytis ulmi spread from about 1930 in the United States. Due to the fungus, the population has been decimated by half since 1976. The fungus clogs the water-conducting vessels of the tree, leading to wilting and eventually death of the affected branches and eventually the entire tree. Bark beetles spread the disease from tree to tree. Spraying of insecticides against the beetle is only a temporary measure. A permanently acting treatment is currently not known. Therefore, the stocks will continue to be decimated, especially as the American elm is particularly vulnerable.

Attempts to avoid this vulnerability by crosses with other elms, have not yet led to resounding success, because resistant species are also disadvantages. The Siberian elm, for example, lack of balanced growth and the wood is much more brittle and splinter easily.

The American elm is the official state tree of the U.S. states of Massachusetts and North Dakota.

Journal of the American elm