From the Super Mario Wiki
Bananas are common tropical fruit from the Super Mario, Yoshi, and Donkey Kong series. They are based off of the nonfictional fruit of the same name, specifically, the cavendish banana. They grow in many tropical islands of the planet, such as on Yoshi's Island and Isle Delfino. Bananas are widely used as food due to their restorative properties and Banana Peels are also used as an offensive weapon in sports competitions such as the Mario Kart series.
The Banana is the most common item featured in the Donkey Kong series of games. This fruit appears in every single Donkey Kong Country and Donkey Kong Land title. They work similarly to the Coin from the Mario series. In these games, collecting one hundred bananas will give a Kong an Extra Life. It is possible for the Kong Family to collect every single banana that appears in the games. Additionally, bananas often point in the direction of secret areas, hidden items, and the end of a level. A Banana Bunch is worth ten regular bananas, and Donkey Kong can sometimes find one by ground pounding in particular spots.
In Donkey Kong 64, there are five colors of bananas - each color can only be collected by a specific Kong; yellow for Donkey Kong, red for Diddy Kong, purple for Tiny Kong, blue for Lanky Kong and green for Chunky Kong. Bananas are needed to feed Scoff in order to allow Troff to open the door to the level's boss. There are exactly five hundred bananas (one hundred for each of the five colors) in each of the game's seven levels, for a total of three thousand, five hundred bananas in the entire game. In this game, Banana Bunches are worth five bananas. Banana Balloons appear exclusively in this game, and are worth ten bananas. However, the Kongs must pop these balloons with their weapons in order to obtain their bananas.
Normal bananas and banana bunches also appear in Donkey Kong Jungle Beat, this time called Beats. In this game, Donkey Kong's banana total acts as his overall health (in the New Play Control! version, they only act as his health for boss battles); losing all of his beats results in a Game Over. Normal bananas are worth one Beat, and bunches are worth three, but stringing together multiple combos and clap grabbing multiple bananas increases the amount of Beats they are worth. Additionally, giant banana bunches also appear at the ends of the levels in the Banana Kingdom and the level Banana Banquet. Biting these, as well as the other giant fruits, causes juice to gush out and the level to end. Lastly, there is a minigame after said levels involving Donkey Kong eating as many bananas as he can in the allotted period of time, to increase his Beat total for that level.
In DK: King of Swing, up to 300 bananas can be collected. Donkey Kong can then use the bananas to heal his health or become invincible.
Bananas appear in Donkey Kong Country Returns, Donkey Kong Country Returns 3D, and Donkey Kong Country: Tropical Freeze, reprising their role from the earlier Country games. In this game, Banana Bunches are worth five regular bananas instead of ten. There is also a bigger type of bunch that is fairly rare and worth twenty bananas. Additionally, there are winged bananas that float around in certain areas, which are worth five bananas. In Donkey Kong Country: Tropical Freeze, winged bananas sometimes give Puzzle Pieces when bananas behind it are collected. In the Golden Temple, there are enormous, floating bananas (amongst other fruit) that are large enough for Donkey and Diddy Kong to stand on.
The Banana (also known as the Banana Peel) is one of the most common items in the Mario Kart series and has appeared in every game of the series. A Banana Peel causes a kart to spin-out if the vehicle touches the slippery item, slowing them down by a little. Banana Peels can either be placed behind a kart, or be thrown forward down the track. It can also be held behind the kart as a defensive countermeasure against homing red shells and, to a lesser extent, green shells. Bananas can also come in threes, known as Triple Bananas. When used, three bananas automatically attach themselves to the back of the kart. However, in Mario Kart 8, the Bananas orbit the kart, similarly to Triple Green or Red Shells. Like many other items in the Mario series, the Banana has eyes. The Banana also appears as the emblem of the Banana Cup.
In Mario Kart 64, along with single bananas, bananas appear in fives instead of threes, and are known as Banana Bunches. Banana Bunches function the same as Bananas, except that when a racer runs into the center of the Banana Bunch line when another player is carrying it, a sound effect will play and the player will get considerably slowed down. The icon for Banana Bunches displays only four bananas as opposed to five. In addition, only one of the bananas features eyes.
Bananas return in Mario Kart: Double Dash!!. There is also a larger variant exclusive in the game called the Giant Banana. When a driver hits a Giant Banana, the fruit will split into three normal Bananas spread on the track. This gigantic special item can only be used by Donkey Kong and Diddy Kong (as well as King Boo and Petey Piranha, who can use any special item). The Giant Banana is capable of blocking nearly every single item and it can even deflect a Bowser Shell (but the Bowser Shell destroys it). A Giant Banana also has a longer duration of the player spinning out than a normal banana. The Giant Banana later appears as a piece of furniture in Animal Crossing: City Folk.
Club Nintendo comics
In the Club Nintendo comic "Super Mario Klemp-Won-Do: Muskeln sind nicht alles!", Mario used some Bananas to make his opponent Blanka slip and fall.
Being the Kongs' favorite food, Bananas serve as the main victuals in the comic "Donkey Kong in: Banana Day 24" when Donkey and his friends travel to Outer Space in order to stop aliens from pulling Earth away from the sun. As it turns out, the culprits just erroneously took the planet for a huge coconut, a fruit their species adores. Diddy suggests to give Bananas to the extraterrestrials as a compensation to get Earth back. This plan works, and the aliens are enthusiastic about the Bananas' taste.
Their use as weapons in the Mario Kart series was referenced in the comic "Die Jagd nach dem Nintendo 64: Krawall im All," when Mario and Luigi dropped some Banana Peels in front of Wario and Bowser, as they were competing to find a Nintendo 64-like spaceship.
Banana bunches also appear in Yoshi Touch & Go. If a Yoshi eats one, it will get three more eggs.
Bananas also appear in WarioWare: Smooth Moves, in the Mona's microgame Shakedown, where in the first level, the player should shake a Banana to free it from fleas. They also appear in Boot Camp, where, also in the first level, the player should beat the Big Nose by throwing banana bunches at its nostrils.
In WarioWare: D.I.Y., the microgame Food Colors features red and yellow foods that must be placed on the matching trays. The Banana Bunch must be obviously placed onto the yellow tray. Eventually, bananas reappear in the game's WiiWare counterpart WarioWare: D.I.Y. Showcase, in which a microgame called DK Country has Diddy Kong getting shot out of a Bonus Barrel and collect six bananas, whilst avoiding a Zinger.
Mario Party series
The Banana is a popular item that shows up in many minigames in the Mario Party series. They are mainly featured in Donkey Kong minigames, where bananas are worth one, two, or three coins depending on a random multiplayer. The banana also appears in many Mic Minigames. In Mario Party 5 and the other Mario Party games after, there is a kind of banana called Banana Bunches. Banana Bunches are worth five bananas. They are mainly found in Donkey Kong minigames.
In Mario Party 9, Bananas replace Mini Stars in the unlockable board DK's Jungle Ruins. On this board, the players' goal is to collect the most Bananas. They can be won on this board in all the same ways that Mini Stars can be won on other boards. Z-Bananas also appear on this board as a counterpart to Mini Ztars.
In Luigi's Mansion, Garbage Can Ghosts will throw Banana Peels on the floor. Luigi can slip on these peels, damaging the plumber with 5 HP taken away (10 HP in the Hidden Mansion). They can also be found lying on the ground in the Dining Room, where Mr. Luggs resides.
Bananas are one of many food items in Super Smash Bros. Melee and Super Smash Bros. Brawl. In Melee and Brawl they restore 5% damage; in Super Smash Bros. for Nintendo 3DS, however, bananas restore only 3% damage, and only appear in Tortimer Island stage. The Banana Peel also appears as an item in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS, and will later appear in Super Smash Bros. for Wii U. Once thrown, anyone who walks over it will trip and fall onto their back. It is also used in Diddy Kong's down special move.
Super Mario Sunshine
Bananas grow throughout the Isle Delfino and are sold in Delfino Plaza's market sector by a street vendor. A local woman took enough interest in them to request Mario's help in gathering them. In Ricco Harbor, a supply of Bananas and other fruit are stored in a gigantic tank used in the episode "Yoshi's Fruit Adventure". Hotel Delfino in Sirena Beach sell the fruit at fruit bars as well. The Yoshis on the island turn into Pink Yoshis after eating them.
Mario Power Tennis
In Mario Power Tennis, in the mode where players can hit the balls through Item Boxes, the Banana tends to appear, known as "Slippery Danger" within the game. The player has to hit the ball with the racquet in order to use the item. When used, the banana will be attached with the ball until it stays still on the ground in the case the ball bounces. Also,the Garbage Can Ghost in the Luigi's Mansion stage throws bananas that have the same function as the regular bananas as a stage gimmick.
Mario Strikers series
In Mario Strikers games, the Banana acts as an item that players can collect. Once used, the player will drop three or five banana peels behind them, which will proceed to knock over any player who runs into them. This includes both the opponent, and the user. If used near an edge, only a few banana's will stay on the field, as the other banana's will fall off the stadium. A similar item is the Giant Banana.
During Diddy Kong's ground entrance, he pulls out a Banana, and whacks it on his hand, which is used to say that he is going to crush his opponent.
Super Mario Strikers
Giant Bananas also appear in Super Mario Strikers and they are used by Donkey Kong as a special power-up.
Mario Strikers Charged
In Mario Strikers Charged, there is a version of the banana called the Giant Banana. The Giant Banana is one of the many items used by the players. When used, the player drops a giant Banana behind them, which hits anyone who runs into it. The Giant Banana has a larger range, and can hit more than one player. The Giant Banana is perfect to use when one is being chased. However, unlike the smaller bananas, the Giant Banana item only deploys one banana, not multiple bananas.
Mario Sports Mix
Banana Peels reappear in Mario Sports Mix. They can either stop opponents for a short time, or power up the ball or puck. When used as an item shot, the ball will make a curved path, a reference to the face that bananas themselves are curved, and can cause opposing players to slip if they touch it. In Western Junction, a train with cars full of Banana Peels may drive through the court, and Shy Guys on board the train will throw Banana Peels on the court so any player may slip over them.
Trophy information from Super Smash Bros. Brawl
Bananas exclusively grow on trees in banana bunches of three or ten. Clusters of three grow on trees that grow multiple types of fruit, such as the Super Happy Tree or the fruit tree of Pianta Village. However, trees that exclusively grow bananas are capable of growing many more. These trees can only be found on Donkey Kong Island and the surrounding isles. The largest known crop of bananas is the Banana Plantation on Donkey Kong Island.
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