Gnome

"Gnome saliva is enormously beneficial! Luna, my love, if you should feel any burgeoning talent today -- perhaps an urge to sing opera or to declaim in Mermish -- do not repress it! You have have been gifted by the Gernumblies!"

- Xenophilius Lovegood to his daughter during the Wedding of William Weasley and Fleur Delacour.

A gnome, or garden gnome is a magical creature commonly known to infest the gardens of wizarding households, the correct taxonomical name for which is purportedly Gernumbli gardensi, or sometimes referred to as Gernumblies. They are found throughout Europe and North America. A gnome in the Muggle world is an inanimate statue that look like a small Father Christmas.

Nature
Gnomes can reach a size of approximately one foot (making them smaller than the three foot erklings ), are usually brown in colour and have disproportionately large heads, making them look like potatoes with legs. Their feet are hard and bony, and they do not look anything like the of Muggles (which, according to Ronald Weasley, look like little Father Christmases with fishing rods).

Ecology
Gnomes live in burrows underground, where they dig up and eat the roots of plants, creating little heaps of earth around gardens a lot like moles (and as such causing considerable damage to them). Gnomes also seem to like worms and Bertie Bott's Every-Flavour Beans. The natural predator of the Gnome is the Jarvey.

Crookshanks was fond of chasing gnomes around the garden of The Burrow, and the gnomes seemed just as fond of being chased. According to Muriel, they are quick breeders.

Uses
According to Xenophilius Lovegood, having an infestation of these creatures in one's garden is a sort of blessing. When his daughter Luna was bitten by a gnome, he exclaimed that gnome saliva had many unusual and beneficial properties, such as the ability to suddenly increase one's creativity (in particular, he said it might make one have the urge to sing opera, or give speeches in Mermish). Luna then told Harry that her father had done a lot of research of Gernumbli magic, so at least in the Lovegood's view of things (which always has to be taken with a grain of salt) gnomes may possess unique magical abilities, distinct from wizarding magic.

Interaction with humans
Because of the havoc they wreak upon gardens and the fact that they are somewhat of a giveaway of wizarding homes, Gnomes are deemed pests by the wizarding community. "Gnome-control" typically consists of taking hold of the gnomes, swinging them around until they are dizzy, and then throwing them beyond the yard's perimeter fence or wall. Gnomes have the ability to speak, or at least make noises, saying 'Gerroff me!' which sounds like 'let go' when people are de-gnoming, they are also able to scream when thrown away and mumble angrily when they walk away, however they can laugh when a de-gnoming is not done properly.

Interestingly, the species has such a low level of intelligence that when a de-gnoming is being carried out they will hurry out of their burrows to see what's causing the commotion, which only renders them easier to catch. Alternatively, one can use a Jarvey to de-gnome a garden, but this method is considered much too violent and thus is seldom used.

The Weasleys had to regularly de-gnome the garden by throwing them over the hedge. However, the gnomes always sneaked back in since Arthur Weasley was soft on them and thought they were funny. This may suggest that they have a bit intelligence, or a clever sub-species of the gnomes exist.

Appearances

 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * Harry Potter and the Deathly Hallows: Part 1 (video game)
 * Fantastic Beasts and Where to Find Them
 * LEGO Harry Potter: Years 1-4
 * LEGO Harry Potter: Years 5-7
 * Harry Potter Trading Card Game
 * Pottermore (http://www.pottermore.com/en/book2/chapter3/moment3)

Notes and references
Gnome Skrzat