I don't have any that are very old myself but it is a very interesting topic. For trees I know Pinus longaeva to reach >8000 years. The really big ones seem to be somewhat determinate and rarely top 3000 years. Creosote bushes may top 25,000.
The oldest orchid in cultivation is probably at Kew - they first recieved orchids in 1818 and I think they have some that are at least 150 years old.