Dragon Nip (Franchise)

Dragon Nip is a plant first introduced in the first Film, How to Train Your Dragon.

Description
Dragon Nip is a green grass plant, which grows to approximately half the height of a full-grown Viking (which is the height of Hiccup). It is described as having a garlicky smell. In the game, School of Dragons, it grows in short grass-like bunches in the player's garden. In the Franchise, it is portrayed both as growing wild and cultivated. It appears to prefer sunlight.

It also looks similar to "Cat Grass", which is another plant fed to cats and is often the young shoots of Oat plants.

Function
Dragon Nip alters Dragon behavior, paralleling Cat Nip in real life. It effects different dragons differently, ranging from no reaction, to relaxation, to playfulness, to aggression (very much like the variable influence in cats). Depending on the Dragon species' reaction, Dragon Nip has been employed in Dragon training.

When Night Furies and Gronckles has dragon nip rubbed on the tip of their nose and around their face, their pupils dilate, they stop flying or attacking and they begin to rub the dragon nip over their bodies, rolling in it if possible, and playing around in it or with it. One of the most effective known ways of taming a Gronckle is to rub a bit of dragon nip on its nose, then scratch and tickle it until it bonds with the tamer. Whispering Deaths, however, appear to not be affected by Dragon Nip at all.

How to Train Your Dragon (film)
Dragon Nip first appears during the time Toothless and Hiccup spend together. During a flight practice, the two are blown away and land into a spot full of grass, that has a calming effect on Toothless. Hiccup takes some of the grass, and uses it several times during Dragon Training on the Gronckle, which is also how he won the Training.

Book of Dragons
Dragon Nip is briefly mentioned in the part about Gronckles, where Hiccup claims that a Gronckle won't stay mad at you if you feed it a little Dragon Nip.

Dragons: Riders of Berk
In episode 14, "What Flies Beneath", Hiccup attempted to use dragon nip to tame an attacking Whispering Death, but sniffing it only made the dragon sneeze. Astrid is implied to have eaten dragon nip once, and it is also implied to have had some effect on her.

School of Dragons
Players are given a farm to raise livestock and also crops, to harvest and complete Farm Jobs (quests). One crop is Dragon Nip, and is the cheapest crop a player can buy. It takes 2 minutes to grow in the game.

Objects to decorate the player Hideout also includes a broom whose bristles are made of Dragon Nip.

Trivia

 * Many fans believe that Dragon Nip is in fact Garlic Grass, backed up in the episode "What Flies Beneath" where it is said that these grass-like plants smell like garlic. "Garlic Grass" could refer to any number of species in the Allium family, such as Allium tuberosum or Allium Canadense.