Entwife

Entwives were female Ents. They were put upon the earth by Yavanna to protect her trees along with their husbands the Ents. According to Treebeard, Fimbrethil was the most beautiful of the Entwives. However, in the Third Age, the Entwives abandoned the Ents in order to start a garden east of Fangorn in the Brown Lands. When Treebeard went searching for them, he could not find them.

Many hundreds of years later, Sam Gamgee the Hobbit claimed his cousin Halfast Gamgee saw a "walking tree" in the North Moors of the Shire. It is likely that this was an Entwife. If not, it was a Huorn of some kind. It is very possible that Entwives went extinct due to one or a number of the wicked creatures inhabiting Middle Earth prior to the War of the Ring.