Jacaranda, in particular, seem to have impossibly huge aggro ranges and impossibly huge ranges on their annoying "root slap" ability (which the veterans spam on short cooldown without warning, precluding evasion/mitigation, at ranges greater than 1500, beyond the range of a trait-enhanced ranger longbow). Sand portal to the the top of the mesa for one of the griffon roosts in Desert Highlands, you end up among normal and veteran Jacaranda, along with a tempting rich orichalcum vein camped by a veteran. You can't just fire stability, ignore the damage and try to gather the orichalcum. Every Jacaranda on the mesa pulls to you, your stability ends, you get thrown around continuously by "root slap", and burned down in seconds by multiple overlapping AOE. If you decide to work towards the orichalcum gradually, clearing the normal Jacaranda from the edges inwards, finally tackling the camping veteran, in short order every remaining Jacaranda on the mesa will join in. They don't do so immediately, suggesting they are not linked. They seem to aggro at range, one after another (off of each other, perhaps? a kind of linking?), until suddenly you are dealing with half a dozen or more. And they respawn quickly enough that the supply even in a very local area is for all practical purposes infinite. Have to kite continuously, try to interrupt... and like as not be ground down. A task for 2+ players, it seems. A suicide mission for many solo builds. A lot of forged and branded seem to work the same way. Tangle with one, safely to begin with, and you end up attracting many, again with ranged AOE, and the dead respawn quickly. And I have lost track of how many times I have been one-shotted off of my mount by ranged branded attacking in unison, often at ridiculous ranges. Have not had too much trouble with Harpies... just haven't had much need to travel in those areas.