Cactus

The Cactus is the primary (and only non-instant) anti-air zombies Plant. According to its Suburban Almanac entry, it is female.

The Cactus could be any member of the genus Cactaceae, but it most resembles a Saguaro Cactus, but with a red flower instead of a white one.

Usage
The Cactus is essentially a Peashooter that shoots spikes, although it can stretch into the air to pop Balloon Zombies' balloons.

Suburban Almanac Entry
Cactus

Cactuses shoot spikes that can hit both ground and air targets.

Damage: normal

Range: ground and air

She's prickly, sure, but Cactus's spikes belie a spongy heart filled with love and goodwill. She just wants to hug and be hugged. Most folks can't hang with that, but Cactus doesn't mind. She's been seeing an armadillo for a while and it really seems to be working out.

Cost: 125 (100 in Versus Mode)

Recharge: fast

Strategy
Build a column of them to keep your lawn safe from Balloon Zombies. They also make a good substitute for the Peashooter on any level you might encounter Balloon Zombies. Although the cost difference is negligible, there is a disadvantage that if even a single Balloon Zombie comes into the lane, all of the Cactus will rise and fire at it. If there are no Balloon Zombies, however, you may be better off with Peashooters. It is cheaper in pool levels to use 2 Cattails instead of six Cacti.

Trivia

 * The Cactus is one of the 3 non-explosive plants that can get rid of the Balloon Zombie. The two others are the Cattail and the Blover.Cactus123.jpg
 * Even though the Cactus and the Cattail have the same projectile, the Cactus' projectile is faster that the Cattail's, but shoots at a longer interval.
 * If stretching, the Cactus has the height of a Tall-nut.
 * The Cactus, the Cattail, and the Sea-shroom are the only projectile-shooting plants having a projectile which has a color not similar to the plant's color.
 * The Cactus cannot work on the slope (except for the 5th row) on Roof levels. This is strange because the Cactus can stretch to the height of a Tall-nut, but does not do that to shoot at approaching zombies on the roof.
 * Cactus is one of the twelve plants that appear in the seed selection screen after you get the Grave Buster on the online version, the others are: Ice-shroom, Lily Pad, Potato Mine, Threepeater, Tangle Kelp, Jalapeno, Spikeweed, Torchwood, Tall-nut, Doom-shroom and Blover.ProjectileCactus.png
 * On the loading screen, her pollen balls are red but during gameplay they are yellow.
 * In the mini-game Portal Combat, when a Cactus shoots a high spike, it will not float over a portal which is weird because the spikes seems to be high enough to pass over it.
 * If there are two Balloon Zombies the Cactus will shoot three spikes, possibly because the Cactus registers three Balloon Zombies.
 * The Cactus and Cattail are the only with spike-shooting plants.
 * She said she's prickly, but not only is she literally prickly because she's a cactus, her spike is similar to Cattail's own.
 * If there's two Cactus's in one lane both will shoot at the Balloon Zombie; one will hit it, one will not.
 * When the Cactus targets a balloon zombie far away, she shoots 2 projectiles.
 * Even with its prickly body, Cactus is as vunerable as a normal plant.
 * The Cactus's flower may or may not be referenced as headwear.
 * If not, it may just simply be seen as a growth on top of her head.
 * If so, the Cactus is one of four plants that have headwear. The others are the Cattail, the Gatling Pea, and the Imitater.
 * The Cactus has a much narrower snout than any other shooting plant.
 * Cactus's sun is 100 in Versus Mode, the sun is 100 used by Peashooter.
 * Cactus is equivalent of Imitater Peashooter in Versus Mode.