Ulmus davidiana

The David elm, scientifically named *Ulmus davidiana*, is a small deciduous tree. This means it sheds its leaves every year. It is a significant species because of its resilience and unique growth habits. This tree is widely distributed across several Asian regions. You can find it in China, Mongolia, Korea, Siberia, and Japan. It often grows in wetlands near streams. These trees typically thrive at high elevations between 2000 and 2300 meters.

Physically, the David elm has several distinct characteristics. It can reach a maximum height of 15 meters. The trunk is relatively slender, usually measuring less than 0.3 meters in diameter. This slender trunk supports a dense canopy that casts heavy shade. The bark remains smooth for a long time during the tree's life. Eventually, the bark becomes longitudinally fissured, which means it develops long cracks. The leaves are obovate, meaning they are shaped like an egg with the wider end at the tip. These leaves are less than 10 centimeters long and 5 centimeters wide. The upper surface of each leaf feels rough to the touch.

The reproductive cycle of the David elm follows a specific seasonal pattern. In March, the tree produces flowers on shoots that are in their second year. These flowers are apetalous, which means they lack petals. They are also perfect flowers and are wind-pollinated. After pollination, the tree develops fruit known as samarae. These samarae are less than 19 millimeters long and 14 millimeters wide. This process ensures the tree can spread its seeds through the environment.

Botanists recognize two main varieties of this tree. The first is *Ulmus davidiana* var. *davidiana*, which occurs only in China. The second is *Ulmus davidiana* var. *japonica*, known as the Japanese Elm. This second variety has a much wider range. There is some scientific debate regarding this classification. Some authorities do not consider *japonica* to be a variety. For example, the *Illustrated Flora of the Primorsky Territory* maintains *Ulmus japonica* as its own separate species. In 1916, the Arnold Arboretum also described them as two different species.

The history of the David elm is tied to the naturalist Armand David. He was a French missionary who collected specimens in the 19th century. Because of his work, the tree is often called the Father David elm. The species was first described in 1873 from the hills north of Beijing, China. Later, in 1916, Charles Sprague Sargent published an enumeration of woody plants collected in western China. This helped document the tree for the Arnold Arboretum of Harvard University. These historical collections helped scientists understand the tree's true identity.

Research has shown that the David elm possesses remarkable biological strengths. At the Morton Arboretum in Illinois, the tree showed good resistance to Dutch elm disease (DED). It is also reputed to resist the elm leaf beetle, elm yellows, and leafminers in the United States. Testing at Ohio State University provided more specific data. Researchers found the tree can perform well on disturbed sites and in calciferous, or alkaline, soils. It also shows a better tolerance for wet soil than previously thought. During a hard freeze in April 2007, at least 50% of emerging leaves survived. This freeze lasted for five days, and temperatures dropped to −6°C (21°F).

Because of these traits, the David elm is a subject of interest for cultivation. A nursery called Hillier & Sons briefly marketed the tree between 1971 and 1977. During that time, they sold only four trees. While there are no known cultivars, the tree shows promise for landscape use. Some saplings have been pruned to improve their structural stability. This helps create a more stable branching pattern as the tree grows. Today, the tree is held in many botanical collections around the world, from the Chicago Botanic Garden to the Royal Botanic Garden Edinburgh.