Populus nigra and populus species in general.
Why You Should Not Plant a Lombardy Poplar!:
Lombardy poplar is a short-lived tree and only survives for twenty or so years. The tree is primarily planted for it's columnar form in windbreaks.
No redeeming features found. Many horticulturists consider the tree taboo with too many associated problems to ever consider planting.
"More Bad Trees"