That's one of those little things that I really will miss about reddit. Same deal with /r/trees and /r/marijuanaenthusiasts. Guess which one was for the arborists.
Those guys were always super cool about it on both sides though, lol. People would post questions about actual trees on /r/trees and a horde of friendly stoners would point them towards the other sub. You'd think you were just being fucked with until you actually went there, and lo, dendrology.