Corylus americana:

American Hazelnut (Corylus americana)

In the past year (2008) I have been asked many many times....

Q: Does this plant need to have a male and a female plant to cross pollinate in order to produce fruit?

A: No,this plant is monoecious. It has both sexes are on the same plant.

This plant is slow to develop at first. I recommend starting with a #5 container size (24"-30" ht.). It takes 4 to 5 years for this plant grow large enough to develop fruit (hazelnuts). This confuses many people who are eager to have fruit. This plant really needs to be in mostly sun during the day. If American Hazelnut is in too much shade it will produce little or no fruit. This confuses many people who are eager to have fruit. In the meantime, enjoy its structure, fall color and habitat cover until the fruit arrive.

More information is available at USDA.
http://www.plants.usda.gov/plantguide/pdf/pg_coam3.pdf