Atomic Palm

Atomic Palm is an attacking plant with area-of-effect damage. She fires coconuts at zombies which deal 1 normal damage shot to all zombies on that tile. However, if she kills a zombie with one of her coconuts, it'll deal 10 normal damage shots to all zombies in a 3x3 area. Note that this only happens from impact damage from the coconut or its area of effect; zombies that die from the explosion will not cause a chain reaction.

Origins
Atomic Palm is based on the coconut palm, a type of palm tree that produces coconuts. Her name is a reference to the atomic bomb, an infamously powerful type of bomb known for its devastating explosions.

Overview
Atomic Palm's coconuts deal 1 normal damage shot to all zombies in a 1x1 area upon impact with a zombie. If any zombie dies from this damage, it'll cause a small explosion in a 3x3 area. Zombies caught in this explosion will not cause further explosions if they are to die from it. She fires a coconut every 1.5 seconds.

Suburban Almanac entry
Atomic Palm

Atomic Palms fire coconuts which deal splash damage, and that explode if they defeat a zombie.

Damage: normal

Explosion damage: heavy Special: coconuts cause explosions if they kill a zombie

Atomic Palm knows everything there is to know about radiation. We're talkin' energy transmissions, ionization, X-rays, gamma rays, cosmic rays, if you get her started, you just can't get her to stop. It might be why she struggles to find a date.

Cost: 275

Recharge: fast

Strategies
Atomic Palm should be used in such a way that she ultimately kills zombies herself as frequently as possible. Fortunately, Atomic Palm is an area-of-effect plant that damages all zombies on a tile, so this slightly raises her chances of killing zombies on her own, but other powerful area-of-effect plants such as Gloom-shroom and Winter Melon may end up mitigating this effect. While Atomic Palm on her own stands as a decent area-of-effect unit, getting the explosions is desirable, as this deals 10 damage to all zombies in a 3x3 area, something that can heavily impair large hoards of weaker zombies.

In order to use Atomic Palm most efficiently, she should be stacked with defensive plants, such as Pumpkin, Wall-nut, or Tall-nut, allowing zombies to group together at the same time and possibly allowing it to kill multiple zombies with the area-of-effect damage from her coconut, something that'd cause a significant explosion. Utilizing multiple Atomic Palms on their own can increase the chance that they'll kill zombies, but players should consider synergies with plants such as Snow Pea, which can group zombies together allowing for the greater chance of clusters that'd be damaged by her explosions. Bulky zombies, such as Zombonis and Buckethead Zombies can counter Atomic Palm well, especially if there are few weaker zombies between them, but some of them can be countered by Magnet-shroom, so packing it alongside Atomic Palm may be recommended.

Trivia

 * The coconuts orbiting its trunk give the impression of electrons orbiting an atom.