NAME: Ulmus americana C. Linnaeus

PLANT FAMILY: Ulmaceae

COMMON NAME: American elm

APERTURATION: Stephanoporate

ORNAMENTATION: rugulate

POLLINATION SYNDROME: Anemophilous

SIZE: 30 - 40 µm in equatorial view

SHAPE: Spheroidal in polar view

FLOWERING DATE: February - April in Texas

NOTES: Like pecan pollen, elm pollen is easy to recognize and is learned quickly by students. Elm pollen is a major cause of allergies. Although anemophilous (wind pollinated) it is visited by honeybees and other insects. Elms flower early in the spring when few other plants are in bloom. On a sunny early spring day, one can hear honeybees foraging on elm flowers.

American elm has been extensively planted as a shade tree in the United States. Unfortunately, they are threatened by Dutch elm disease. Older trees are usually tall with limbs gradually spreading outward to form a wide-spreading crown which is desired in a shade tree.