Spike

Spike(also referred as Thorn) is a type of projectile or a sharp piece of certain plants that is used for damaging zombies in both of the cases. Spikes can be shot by Cactus, Cattail, Homing Thistle, Foxtail, Liontail and Dogtail. Plants including Spikeweed, Spikerock, Endurian and Rose Swordsman use spikes as a part of their body to damage zombies. Spikes are also used as long range projectiles by Cactus and its variations in Garden Warfare games.

Plants vs. Zombies
In Plants vs. Zombies, spike projectiles deal the damage of a pea. They are also the only projectiles that can shoot down Balloon Zombies. In this game, only spike shooting plants are Cactus and Cattail. Cattails shoot two spikes at a time and their projectiles hit the closest zombie in any lane, being able to change directions and even traveling back while Cactus' spikes travel strait. Spikes cannot be set on fire by Torchwood.

In the game, spikes are also essential parts of the plants Spikeweed and Spikerock. Most of the zombies walk over these spikes, hence they constantly get damaged by the aformentioned plants, as long as they stand on them. Spikerocks' spikes deal twice as much damage as Spikeweeds'. Both of the plants can instantly kill Zombonis and Catapult Zombies, however they get hurt by them as well, Spikeweed vanishing in one vehicle destruction, and Spikerock vanishing in nine.

Plants vs. Zombies 2
Spikes return on Plants vs. Zombies 2, with a similar appearance. In this game, Homing Thistles shots homing spikes towards zombies similarly to Cattails but their spikes are slightly different looking green spikes, which deal twice as much damage but are thrown one at a time, wheen compared to Cattail. When fed with plant food, Homing Thistles shoot a number of blue needles at once, which deal heavy damage to the zombies they hit. Cactus' thorn spikes can now pierce through maximum three zombies. When fed Plant Food, Cactus' spikes become blue, and thus Cactus starts shooting narrow blue spike projectiles which appear to be charged with electricity. These blue spikes pierce through four zombies and deal twice as much damage.

Spikeweed, Spikerock and Endurian also use the spikes/thorns on them to damage zombies. Similar to Plants vs. Zombies, Spikeweed and Spikerock hurt zombies that walk over them while Endurian blocks zombies, simultaniously damaging them. Spikeweed's, Cactus' and Spikerock's spikes can instantly kill Pianist Zombies as well as instantly destroy the barrel the Barrel Roller Zombie rolls. However, the former two plants die in one, and the latter plant dies in three destructions. Cactus hides into the ground and uses its thorns as appendages rather than projectiles to damage zombies in a similar fashion to Spikeweed on Plants vs. Zombies 2 when zombies get close to it. Similar to how plant food fed Cacti's projectiles deal twice as much damage to zombies, they also deal twice as much damage when used as a ground attack.

Plants vs. Zombies 2 (Chinese version)
Aside from the aformentioned plants, Rose Swordsman, a monthly special plant, uses its thorn to damage nearby zombies by stabbing them, using it like a sword.

Plants vs. Zombies: All Stars
Cactus, Cattail, Spikeweed and Spikerock return on Plants vs. Zombies: All Stars, and with the upgrade system of the game, new plants that use spikes are added as upgrades to the said plants. Both Spikeweed and Cattail have evolution families in the game. Cactus attacks the enemies by shooting spikes at them correspondingly to its behavior in Plants vs. Zombies. In the game, it is also given an evolution family, as it is the mid-tier on it. Ball Cactus, the downgrade of Cactus attacks zombies by lobbing spiky cactus balls at them. Tree Cactus, being the upgrade of Cactus, attacks zombies by sending sharp spiky shockwaves at them.
 * Ball Cactus → Cactus → Tree Cactus
 * Cattail → Dogtail → Foxtail
 * Spikeweed → Spikerock → Diamond Ground Thorn

Cattail can be planted on the land in this game and it shoots a spike every turn. Dogtail, its upgrade, can shoot five long spikes at once, while Foxtail, the highest upgrade in the evolution family shoots three big spikes at once. Liontail, a scrapped plant, was once planned to be the highest upgrade of Cattail, but later, was replaced by Foxtail.

Spikeweed goes underground in this game; and similar to the other games in the series, hurts zombies that walk over it. Spikerock acts the same way, dealing more damage to the zombies. Diamond Ground Thorn, upgrade to Spikerock and thus the highest upgrade in the Spikeweed evolution family, attacks all the enemies in its lane by going underground and spinning in place.

Durian, a plant very similar to Endurian, is also set to appear in the game.

Trivia

 * Cattail's spikes travel slower than the Cactus' and Homing Thistle's.