First, the trees get a disease that screws up their famously dense and columnar habit. In the Northeast, those poplars are scraggly and patchy, with dense twiggy areas as well as bare ones. A mess.

And then there are the famously water-hungry roots. Like (some) willows, poplars are one of the few trees that actually do "invade pipes" and clog up septic systems, wells, irrigation systems. If you need to see happy poplars, go up to Quebec, where, I'm guessing, the patchy-scraggly disease isn't hardy. (Or maybe because so few other trees are hardy up there, they grow it out of desperation.) 

For gardens South of the (Canadian) Border, poplars should be cut down, never planted. Except for this one:

Gold foliage. Gold! And that stays gold all season. The backs of the leaves are pure white too, so in a breeze the tree shimmers. 

For some reason, this poplar doesn't get the patchy-scraggly thing either.   It might still have the water-hungry roots, but mine is a good sixty feet from any well or septic system, so I say to its roots, "Truffle away!" 

Plus—so atypical for a poplar, which are normally so fast-growing they are trumpeted in those "Gets Thirty Feet Tall In Three Years" ads we all used to see in the Sunday Supplement—the gold-leaved poplars are amazingly slow-growing. Mine is eight years old, by which time a Sunday Supplement popular would be sixty feet tall.

Like many trees and shrubs with interesting foliage, gold-leaved poplars welcome severe Spring pruning (that is, after they get big enough to have anything to prune). I'm not quite ready to pollarding mine. All I've done is to clipping off the branches from the trunk below, so the tree gets the idea that it is in fact a tree, with a "clear" trunk. Even so, the poplar is already like a still photo of a gold explosion.

Gold explosion: I like that in a garden.

PS: The patchy-scraggly poplar is native to the Mediterranean.  So maybe it doesn't like the rain and humidity of the Northeast. The gold-leaved poplar is native to Canada:  it's the fancy cousin of all those happy poplars up in Quebec.  So maybe it grows so slowly here in New England because it doesn't like our sweltering Summers and (comparatively, mind you) namby-pamby Winters.

Whatever: it's a blessing to have a poplar whose roots doesn't have designs on the entire neighborhood, and whose foliage is such a shimmer from May through October.