“Luna, my love, if you should feel any burgeoning talent today—perhaps an unexpected urge to sing opera or to declaim in Mermish—do not repress it! You may have been gifted by the Gernumblies!”
-- Xenophilius Lovegood (DH8)
The magic supposedly done by “Gernumbli gardensi” or garden Gnomes, according to Xenophilius Lovegood (DH8).
- When Luna was bitten by a Gnome in the Burrow garden, her father told her the creature's saliva was "quite beneficial," and could possibly lead to some new talent, such as Opera singing or speaking Mermish (DH8). He is the only source of this information, however, and like many of his theories it has yet to be proven.
- Xeno also believed that Gnomes were "wise," but Ron said the only thing he ever heard Gnomes say were "excellent swear words" they learned from Fred and George (DH8).
- According to Fantastic Beasts and Where to Find Them, Gnomes have no special powers and are merely garden pests (FB).
"Gernumbli" is possibly a composite word meaning "happy on the ground" from "gern" = German for "gladly or happy" plus Old French humble, umble, earlier umele, from Latin humilis "lowly, humble," literally "on the ground," from humus "earth." So the full scientific name would mean "happy on the ground in the garden," which perfectly describes Gnomes.
"Gernumbli" sounds somewhat like "The Jumblies," the title of a whimsical poem by 19th-century British writer Edward Lear.