Entwives were the Ents’ mates, and you don’t see them in the Lord of the Rings because they were lost! they were more interested in controlling growth of plants, and began to wander to different territories and never came back.
Pippin: Why are there so few of you, when you live so long? Are there Ent children?
Treebeard: Brrharroom. There have been no Entings for a terrible long count of years.
Merry: Why is that?
Treebeard: We lost the Entwives.
Pippin: Oh, I’m sorry. How did they die?
Treebeard: Die? No. We “lost” them. And now, we cannot “find” them. I don’t suppose you’ve seen Entwives in the Shire?
Merry: Can’t say that I have. You, Pip?
Pippin: What do they look like?
Treebeard: Hrrooom… I… don’t… remember… now
Pippin: Why are there so few of you, when you live so long? Are there Ent children?
Treebeard: Brrharroom. There have been no Entings for a terrible long count of years.
Merry: Why is that?
Treebeard: We lost the Entwives.
Pippin: Oh, I’m sorry. How did they die?
Treebeard: Die? No. We “lost” them. And now, we cannot “find” them. I don’t suppose you’ve seen Entwives in the Shire?
Merry: Can’t say that I have. You, Pip?
Pippin: What do they look like?
Treebeard: Hrrooom… I… don’t… remember… now