Rectangles are actually pretty interesting. They're pretty easy to dodge going forward or backwards so they can force the enemy to decide to engage or disengage, and they have a lot of interesting interactions with jungle paths where a cast from a perpendicular position at a long path becomes undodgeable and a cast from a parallel position produces a pure wall.
My issue is that it was inspired by a flowerbox and produced a very inorganic shape and concept. It involves plants but Zyra seems all about wild, overgrown, exotic plants, not a tray of marigolds. It kinda feels like giving Warwick a tennis ball or frisbee themed skill because dogs and wolves are kinda related. But I think that's a pretty minor issue as the rectangle makes for some more unique gameplay.