Trees integrated into the structure of the houses? Or just houses with large gardens? (Btw, its entirely possible to have a city with reasonably large parks in them. You just wouldn't call them forests.)
perhaps the reason they called it a subtype was not so much so they could bring it back, but so they could subtype other instant/sorcery spells.
Eg. [Guild spell] [cost]
Instant - guild spell
[effect]
Surely a plant could be obvious in its genericicy, such as dross zombie, (can't think of any other recent examples, but they're there)
Like, cards that seem made for a coreset, because of their simplicity.
And its not the complicatedness that keywords it.
Eg. [Guild spell] [cost]
Instant - guild spell
[effect]
Have you guys never heard of triffids?
Like, cards that seem made for a coreset, because of their simplicity.