Huorns
A Huorn in the New Line film
HuornTrees - or treelike beings - that could walk and speak. Huorns were powerful, wild, and dangerous. The origin of Huorns is somewhat mysterious. Merry Brandybuck speculated that Huorns were Ents that had become more like trees. Treebeard also spoke of trees that had become Entish, so it is possible that some of these became Huorns as well.
Huorns looked like trees, though they were strange in appearance, with twisted roots and long, grasping branches. They generally stood at rest, keeping watch over the ordinary trees. But when roused by a threat to the forest, Huorns could move swiftly and kill efficiently. It was difficult to see them move, for they seemed to be wrapped in shadow and they would appear as if out of nowhere. Huorns were able to speak with the Ents, and other people could hear the Huorns' voices murmuring through their branches.
Fangorn Forest was the home of many Huorns. Some of the Huorns stood on the eaves of the woods or scattered among the ordinary trees. There were also hundreds of Huorns in dark patches deep in the forest. Huorns could be dangerous to intruders, particularly to Orcs who wantonly cut down and destroyed trees.
During the War of the Ring, a great number of Huorns accompanied the Last March of the Ents to Isengard on March 2, 3019 of the Third Age. At midnight, Saruman's army left Isengard and headed to Helm's Deep, and many of the Huorns followed them. Others remained with the Ents and formed a ring around Isengard. Some of the Huorns helped the Ents gather the waters of the River Isen in order to flood Isengard. When Gandalf arrived on the night of March 3 seeking help, Treebeard sent hundreds more of the Huorns to Helm's Deep.
At Helm's Deep, the Huorns filled the Deeping-coomb, and it seemed as if a forest had grown there overnight. At dawn on March 4, King Theoden led a charge from the Hornburg, and Gandalf and Erkenbrand brought reinforcements down the western side of the valley. Saruman's army found their line of retreat cut off by the Huorns. The Orcs fled into the forest and the Huorns killed every last one of them.
The next night, the Huorns buried the Orcs that had been slain by the Rohirrim during the Battle of Helm's Deep in a great mound called the Death Down. The Orcs that had disappeared into the Huorn-wood after the battle may also have been buried there, though no one ever investigated the grave closely. The Huorns passed the camp of the Rohirrim on the Isen like a cloud of darkness and they returned to Isengard and then to Fangorn Forest. "Thus they were revenged upon the Orcs." (TTT, p. 158)
Names & Etymology:
The name Huorn apparently has something to do with the Huorns' ability to speak. According to Pippin, "They still have voices, and can speak with the Ents -- that is why they are called Huorns, Treebeard says." (TTT, p. 170)
The word orn means "tree" but the meaning of the element hu is not clear. It may be related to hûn meaning "heart" or hûr meaning "readiness for action, vigor, fiery spirit." "Active tree" would be a suitable definition, though it does not specifically address the Huorns' speech capability.
Another possible derivation of hu is from the root KHUG meaning "bark" (the noise a dog makes, not the skin of a tree) or "bay" (like a hound). This element is found in the name of Huan the Hound. According to The Lord of the Rings: A Reader's Companion this definition "appears to be supported by unpublished etymological notes by Tolkien," but this is not further explained.
The three earlier names Tolkien used - Galbedirs, Lamorni, and Ornomi - all meant "talking trees." Galbedir is derived from the stem galad meaning "tree" and bedir a form of pedir possibly meaning "speaker" from the stem pet - "say." Lamorni contains lam meaning "sound" and orni meaning "trees." Ornómi - translated as "trees with voices" (HoME VIII, p. 55) - contains orne meaning "tree" and ómi from óma meaning "voice." An alternate version was spelled Ornómar.
Sources:
The Two Towers: "Treebeard," p. 71, 90; "Helm's Deep," p. 146-47; "The Road to Isengard," p. 148-55, 158; "Flotsam and Jetsam," p. 170-76
The Return of the King: "The Passing of the Grey Company," p. 50
The History of Middle-earth, vol. V, The Lost Road and Other Writings: "The Etymologies," entries for GALAD, KHO-N, KHOR, KHUGAN, KWET (PET), LAM, OM, ORO
The History of Middle-earth, vol. VIII, The War of the Ring: "Flotsam and Jetsam," p. 47, 50, 55-56, 59 note 11, 59-60 note 15; Index entries for Galbedirs, Lamorni, and Ornomi (defined as "Talking Trees")
The Lord of the Rings: A Reader's Companion by Wayne G. Hammond and Christina Scull: "Flotsam and Jetsam," p. 425
Lambengolmor message archive (on Galbedirs, Lamorni, and Ornomi)