Fate Reforged has more dragons than you can shake a stick at. Not that you should shake sticks at dragons. That seems like a pretty good way to get roasted.
Ill-framed folksy sayings aside, there are a lot of dragons in Fate Reforged, including (for just the third time in Magic's history) a mono-green Dragon—the rarest of all Dragons.
The other two? The more recent one you probably already know, as he was featured in both Champions of Kamigawa and Modern Masters.
The very first mono-green Dragon, however, was this all-star from Mirage.
All three mono-green Dragons only saw print as part of a cycle of monocolored Dragons. The Mirage cycle was somewhat famous (or infamous, depending on your point of view) for quite a while. None of them saw much serious tournament play, but they earned a place in more than one young Planeswalker's heart for their uniqueness early in the game, even if Crimson Hellkite was the Mirage Dragon that kept kids up at night.
But Canopy Dragon's lack of flying, and the general lack of green Dragons across Magic's history, is meant to emphasize the fact that green is really, really not the color of flying. And Dragons, as we all know, tend to fly (Canopy Dragon's difficulty lifting off notwithstanding).
In fact, multicolored green Dragons tend to be at least partially red, making them Dragons first (the red portion), and large, tramply, and prodigiously reproductive second (the green part).
Outside those few exceptions, all of green's Dragons come from one of two places: cycles and Jund. For instance, green has members in the Legends Elder Dragon Legend cycle, the Invasion cycle, and the Planar Chaos cycle. Jund, home to a ton of different dragons, was teeming with green Dragons with one simple rule—every last one of them was red.
So when you crack packs of Fate Reforged, if you open one of the green Dragons—especially Destructor Dragon—take a moment to appreciate just how rare green Dragons really are.