Named/Are Named

[Unregistered]

"In a desert exists plants, are named barbs, which require no water at all."

1. What is the grammar reason requiring the pronoun "which" - "which are named"?
"In a desert exists plants, which are named barbs, that require no water at all."

2. "In a desert exists plants, named barbs, which require no water at all." - is "named" past simple and why is that possible and not "are named"?

[svartnik]

"In a desert exists plants, are named barbs, which require no water at all."

1. What is the grammar reason requiring the pronoun "which" - "which are named"?
"In a desert exists plants, which are named barbs, that require no water at all."

2. "In a desert exists plants, named barbs, which require no water at all." - is "named" past simple and why is that possible and not "are named"?

In a desert exist plants called barbs, which need no water at all.

This grammatical structure, AVS, is not very common outside the realm of literature and archaic English, if I am not mistaken.