Cattail

The Cattail is the upgrade for the Lily Pad. It costs $10,000 to buy from Crazy Dave's shop and 225 sun to upgrade the Lily Pad in the pool. Its tail and name are based on the Typha latifolia the cattail or reed, a perennial herbaceous in the genus Typha. Its face however, is based on the domestic cat. It fires Spikes to any lane at a speed of 2x. It is unlocked after level 4-4.

Suburban Almanac Entry
Cattail 

Cattails can attack at any lane and shoot down balloon zombies too.

Firing Speed: 2x

Must be planted on lily pads

" Woof!" says Cattail. "Woof woof woof! Does this confuse you? Do you expect me to say 'meow' like a cat because the word 'cat' is in my name and I also look like a cat? That's not how things work around here. I refuse to be pigeonholed."

Cost: 225

Recharge: very slow

Usage
The Cattail has the damage and rate of fire of a Repeater. The Spikes it fires are homing, and can hit zombies anywhere. It attacks zombies closest to the plant, though it prioritizes Balloon Zombies. However, they can only attack a few Shield Zombies around their Shields. It is very useful for killing Digger Zombies if they're in the back row, as it will kill them before they can move.

Strategy
Because a single Cattail can cover all six lanes, it makes a good early defensive plant. It also helps deal with Digger Zombies and Imps as well as Balloon Zombies. Unfortunately, all your Cattails will usually fire at the same target (except under certain conditions), and when that target dies, spikes in the air are wasted. This limits the effectiveness of large numbers of Cattails. It is a good idea to use Cattails in limited numbers in Survival Mode. Also, do not rely on Cattails for pool defense, since they will be inevitably overwhelmed. When playing a Survival: Pool Hard level, you want to get Cattails, but back them up with Repeaters in the pool. 4 Cattails, 2 Repeaters and two Sunflowers/Twin Sunflowers is the ultimate defense.

Trivia

 * The Cattail is the only aquatic plant that is an upgrade.
 * It's also the only Upgrade Plant that upgrades from an unoffensive plant.
 * The Cattail does the damage of a pea and rate of fire like a Repeater, making it in aquatic version of a Repeater.
 * However, it's shots are homing, so it's much better.
 * A Cattail can be downgraded to a Lily Pad if you have a Pumpkin on it and try to dig up the Cattail, as that would cause the Pumpkin might fall into the water otherwise.
 * Bungee Zombies can also downgrade a Cattail with a Pumpkin.
 * The Cattail is the most expensive aquatic plant, costing 225 (25 extra for Lily Pad) Sun with a 250 sun total.
 * A Gatling Pea is 450 total (with Repeater), but Cattails are 250 total, has the same rate of fire as the Repeater and can take out Balloon Zombies too, making it save sun.
 * During the ending credits of Zombies on Your Lawn, it is shown next to Laura Shigihara's name.
 * According to this website, this is because Cattail is her cameo plant, because she wears a hat similar to Cattails' when it's cold.
 * When a zombie is defeated and the spikes from Cattails are still aiming for the same direction, it will not damage the Zombie behind the defeated one (unlike some other projectiles, which hit the zombies at the back).
 * This may be due to the fact that Spikes are "homed in" on the zombie the Cattail aims for.
 * The Cattail is a pun upon the Typha latifolia, commonly known as a cattail, as evidenced by the Cattail's cat's head and its tail a Cattail seed structure.
 * The Cattail's spike moves slower than the Cactus.
 * The Cattail, the Starfruit, the Gloom-shroom, the Cob Cannon, the Cherry Bomb, the Winter Melon/Melon-pult (splash damage), the Doom-shroom, and the Threepeater are the only plants that can hit zombies in other lanes.
 * Cattail seems to be standing on a folded Lily Pad, or maybe has 4 lily pads for "legs".
 * The Cattail and the Lily Pad are the only aquatic plants that can have a Pumpkin on it.
 * The Cattail is one of the two plants with a tail, the other one being the Cob Cannon.
 * The Cattail, the Cactus and the Sea-shroom are the only projectile-shooting plants that use a projectile that is colored significantly differently from the plant itself.
 * The Cattail's spikes, on the DS version of the game, will sometimes miss the zombies, and keep circling it, until it dies.
 * The Cattail has the longest range among the shooting plants.
 * The Cattail, the Imitater, and the Gatling Pea are the only plants with headwear.
 * If you look closely, the Cattail has one tooth sticking out, similar to the Starfruit, but a fang.
 * It is unknown whether the Cattail is female, or male. However it can be assumed that it's female for it is the cameo plant of Laura Shigihara and it also looks female from the pink hat. It could probably a boy because it is upgrade from Lily Pad, who is a boy, according to Lily Pad's almanac.
 * Cattail can fire in the most directions. The plant that fires in the second most directions is Gloom-shroom (8) and the third is Starfruit (5).
 * The Cob Cannon can also hit the zombies in all directions.
 * Cattail is one of four plants who can fire at a Digger Zombie, the others being Gloom-shroom, Split Pea, and Starfruit.
 * Cattail is also one of three plants who can get rid of Balloon Zombies. The other is Blover and Cactus.
 * Cattail is the only plant to resemble an animal.
 * Surprisingly, Cattail will not aim at a Snorkel Zombie. This is odd because it can fire anywhere on the screen and will aim at Balloon Zombies.
 * The Cattail, Marigold, and Starfruit are the only with one tooth.
 * When a Cattail is targeting a Pole Vaulting Zombie and the zombie vaults, the Spikes will act as it would if the zombie already died, but when the Pole Vaulting Zombie lands, the spike will turn around and attack the zombie again.
 * The Cattail, Lily Pad, Tangle Kelp and the Sea-shroom are the only aquatic plants that have a splashing sound.
 * In the Mini-game Heavy Weapon the Cattail's tail is pink.
 * Cattail bears a slight resemblance to the Pokémon Skitty.
 * It is strange how the Cattail can support a Pumpkin, as the Pumpkin looks like as if it is floating.
 * The Cattail and the Cactus are the only plants to shoot red spikes.
 * The Cattail doesn't act like a cat depsite it's look but more to a dog since it barks.
 * If Cattail is planted in the very front rows, its spike cannot hone into zombies.
 * The Cattail will not attack unless there are zombies in the 2nd lane or farther.
 * The Lily Pad is a male, but the Catail is a female,which is strange.
 * Lily Pad might have a crush on Catail.