Thistle

The Thistle is pretty much a weed version of the Wall-nut, with the added perk of doing 1 damage per second to zombies eating it. That means in 10 seconds, it can kill a normal zombie.

These are very useful against zombies like Digger Zombies and Snorkel Zombies.

If a ladder is placed on it, it will be destroyed after 25 seconds, because that is how much health a ladder has. The only trouble against these are zombies that don't eat it.

Almanac Entry
This plant deals damage to zombies eating it.

Thistle is friends with Wall-nut, although they sometimes fall out. "I am better at defending than you!" shouts Wall-nut. "No, I am!" screams Thistle. "You prickle everyone." replies Wall-nut "So im more socially popular". Thistle sulks in a corner, but that doesn't stop him from letting zombies chew him.