Wattle Trees is a special mission in Bloons Monkey City. The player must pass 25 rounds with only Boomerang Throwers at their disposal, with a free one given at the start and every three rounds (unless on mobile version 1.1 - 1.2.1 due to a glitch). Upon completion, the player is rewarded with $1,000 and the Enchanted Boomerang special item, which increases the Boomerang's popping power by 1 in all games. If the player already has this item they will receive 50 instead. Altogether, four Wattle Trees tiles will appear, two in Grassy Pass and two in Bloon Dunes. In Bloons Monkey City Mobile, which does not include Bloon Dunes, there will only be two Wattle Trees tiles.
Even though it's Boomerangs only in Wattle Trees, in the mobile version, you can place a Monkey Farmer (pictured) if you have one. However, since you can't play Banana Farms in the mission, it is useless.
It is possible to earn Monkey Teams reward through playing this mission if one of the active Monkey Teams events contains a Boomerang Thrower.
In the closed beta version of Bloons Monkey City, Camo Bloons and MOAB-Class Bloons may appear during this mission, depending how far it is from city origin. Since the Boomerang Thrower's Glaive Lord upgrade is the only way to allow the tower to pop Camo Bloons, this was changed in the official release.