American Elm

Order: Urticales
Family: Ulmaceae
Genus: Ulmus
Species: americana

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Photo credit: Katherine Johnson

Identifying Characteristics
  • The American elm is an extremely hardy tree that can withstand winter temperatures as low as −42 °C (−44 °F).
  • The leaves are alternate, 7–20 cm long, with double-serrate margins and an oblique base
  • The crown forms a high, spreading canopy with open air space beneath.
  • The tree is hermaphroditic, having perfect flowers, (i.e. with both male and female parts) and is therefore capable of self-pollination.
  • The flowers are small, purple-brown, and, being wind-pollinated, are apetalous; they emerge in early spring before the leaves

Special Adaptations
  • The American Elm occurs naturally in an assortment of habitats, most notably rich bottomlands, floodplains, stream banks, and swampy ground, although it also often thrives on hillsides, uplands, and other well-drained soils
  • American Elm is wholly insensitive to daylight length, and will continue to grow well into autumn until injured by frost.
  • Seed germination generally occurs soon after contact with the ground, although some seeds are able to lie dormant until the following spring.
  • The "crown" structure was attractive and useful for shade, so many trees were left standing as towns went up around them due to the shade they provided to the streets.

References
Wikipedia. (2012, July 10). Ulmus americana. Retrieved July 10, 2012, from http://en.wikipedia.org/wiki/Ulmus_americana


Katherine Johnson