What plant in the original Plants vs. Zombies allows other plants to be placed on water? Lily Pad does.
In the original game, Lily Pad is an aquatic support plant rather than an attacker. It must first be planted on a pool tile, after which most ordinary land plants can be placed on top of it. This makes it possible to use defenses such as Peashooter, Sunflower, Wall-nut, and many other non-aquatic plants in the pool lanes.
Lily Pad becomes especially important in Pool and Fog levels, where two central rows are covered by water. The plant costs 25 sun and is unlocked after completing level 2-10, just before the game’s pool-focused stages become a major part of the campaign.
Players sometimes confuse Lily Pad with Tangle Kelp or Sea-shroom because all three are associated with water. Their roles differ: Tangle Kelp attacks by dragging a zombie underwater, while Sea-shroom is an aquatic mushroom attacker. Water Lily is also a plausible-sounding name, but the original game’s official plant is Lily Pad.