An interesting example of the perils of using common names for plants. Wikipedia lists no less than 29 different trees (representing 26 different genera), the wood from which bears the common name "ironwood". 23 of these actually have the word "ironwood" in the trees' names.
Rattlesnake Gal's American hophornbeam (
Ostrya virginiana) is in a totally different genus from the American hornbeam (
Carpinus caroliniana) found in southern New Hampshire. Both are commonly referred to as "ironwood". Ishoot308's "ipe" comprises the entire genus Tabebuia, which is native to Central and South America.