There are clones from the same meristem out in the Midwest prarie grasses left over from the last ice age about 10,000 years old or so.

About 5 species of tree in CA get 2000-4900 years old.

The main thing that kills such plants, rot, fungi, pest, fire, toppling(redwood and sequoia's main enemy), ligthing(Bristlecone pine's main enemy), but not pre determined age..........

Regards,
Tom Barr