I guess an encounter with those would be... a brush with death.
...except, y'know, not, because it's a CR 17 monster that can't fly or attack at range. Hell, an archer on a horse could probably kill it with enough time and arrows. Oh, and it's also got 31 plant RHD, so any of you who are still reading can stop now and skip to the end.
Anyways: colossal size, high strength and constitution, average or nonexistent other stats. One slam attack, some natural armor, a 30 ft. aura of poisonous spores, and a 20% chance for piercing melee or ranged attacks to miss, because piercing is the worst damage type despite being presented as on par with slashing and bludgeoning.
I'd like to draw special attention to Scoop, which is basically Improved Grab for Trample, and which is supposed to be one of the bush's main offense modes. Surprisingly, combining two bad abilities doesn't make it good.
So yeah, awful monster, awful abilities, not even some dumb SLAs or a pitiful 'shoot thorn' attack. Don't use this if you're a DM, definitely don't use this if you're a player. -0 LA.