Fire Flower

When Mario or Luigi obtains a Fire Flower, they transform into Fire Mario or Fire Luigi. In this form, they can shoot fireballs that can defeat many enemies. The Flower first appeared in Super Mario Bros., where it could be found in a ? Block if the player had already obtained a Super Mushroom.

In Mario & Luigi: Partners in Time, Fire Flowers are referred to as Bros. Flowers and attack all enemies as well as possibly causing a burn. In addition, there are two related items: the Mix Flower, which when used creates one giant fireball that falls upon the foe, and the Ice Flower, which is used in the same manner as a Bros. Flower but reduces the enemies' stats rather than causing a burn.

In the Paper Mario series, when Mario and his allies use a Fire Flower on their foes, it does three damage to each of them. It's a common item and isn't very useful when Mario and the gang start fighting stronger enemies.

In Mario vs. Donkey Kong 2: March of the Minis, when a Mini-Mario touches a Fire Flower, he would become Fire Mini-Mario and begin rapidly shooting fireballs.

A similar item called a Power Flower appeared in Super Mario 64 DS. In Super Mario World and Super Mario Land 2, the Fire Flowers were shaped liked tulips.

The Super Smash Bros. series has Fire Flowers as well. Once picked up, the player could use it to expel fire, hurting anyone who came too close. It does have a limit to how much fire it can use, and will lose its abilities after constant use. However, this doesn't mean it is worthless. The player could throw the Fire Flower at someone to burn them.

Trivia

 * In a similar manner to how Mario and Luigi have both eaten and "absorbed" Mushrooms throughout their games, there is much controversy over whether Mario must eat a Fire Flower or simply touch it to became Fire Mario. Although most games make Fire Flowers simply disappear upon contact with Mario, Paper Mario: The Thousand-Year Door seemingly confirms that Mario does indeed eat Fire Flowers, as is indicated by a certain optional scene where Mario informs a Lakitu cameraman that he "shoots fire when he eats a flower".