Winter Green's Incorrect Secondary Damage

In Winter Green's description: "Deals secondary damage to enemies in its outer 3x3 blast radius..."

Winter Green's Secondary Damage: 265

I tested this on an Imp Level 1, which has 161 HP.

The imp survived the Winter Green's secondary damage, and then lasted 5 more peashooter hits (20 damage each) before dying.

In other words, Winter Green's secondary damage did between 61 and 80 damage. This does not match its listed Secondary Damage.

I have not checked Freezar Salad.