Water only passes through recently dead xylem?

[doc3232]

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So xylem dies when it "matures."
But very old xylem becomes heartwood and only functions in structural support, but the most recent xylem is still alive and has no function?
Only the old xylem (but not too old) transports water?

Am I right?

 

[utdent20]

according to schuams' xylem after death carry water function best.