Glow-shroom

The Glow-shroom is the first plant of Victorian London, obtained in Level x-1. Glow-shrooms fire luminescent spores at zombies in the same way as a Peashooter. Illuminated zombies can be seen through fog. Illumination also allows the targeting of 'invisible' zombies, such as the Rogue Zombie, Zombie Spy and Thief Zombie. However, illumination requires that these zombies be initially targetable.

Suburban Almanac Entry
Glow-shroom loves to party. In fact, he is the greatest party fungus of the mushroom kingdom. Every night, his bright green glow illuminates the Thames as he hosts the biggest parties this side of Britain. Lights, streamers, disco-balls, you name it, all there! It draws plants and mushrooms from all walks of life. No zombies allowed of course. Glow-shroom wouldn’t want any zombie toffs to put a spanner in the works.

Plant Food
Splatters every zombie on the screen with luminescent spores.

Strategies
Glow-shroom is the only plant available in the early levels of Victorian London that allows zombies to be seen through fog. Although it is not strictly necessary to plant these, it is highly advised. It is recommended to place one Glow-shroom in each lane.

Since the Glow-shroom cannot reveal zombies behind the first, it is ideal to be vigilant and kill off frontline zombies as soon as possible. However, the Sweet Potato could be used to target lagging zombies in a few lanes.

In later rounds, the Glow-shroom can still be useful as it does not have to be planted near the front lines. This can otherwise cause problems. It can help when fog isn't currently illuminated to observe the frontline of approaching zombies. It can assist in targeting thieves too.

Trivia

 * Based on mycena chlorophos, a species of bioluminescent fungus that emits a bright green glow.
 * Glow-shroom is the first mushroom in the PvZ series to allow players to see zombies through fog.
 * It is also the first plant in the series to make individual zombies visible instead of simply removing fog.