Immortal Trees Show Signs of Aging

With immortality comes immobility.

Because some quaking aspen trees can reproduce by copying themselves, some people have wondered whether they might live forever, at least theoretically. But even if that’s possible, they’re still not immune from the ravages of time.

As aspen clones grow older, a slow buildup of genetic mutations impairs their pollen production. After a few tens of thousands of years, they won’t produce any pollen at all.

When that happens, trees will still be able to sprout clones from their root tips, but they won’t be able to make seeds. They’ll be stuck in place, vulnerable to disease or disaster.

...

Individual trees have a lifespan of about 200 years, but clones — scientists consider the collective as as single entity — can sprawl for acres, all descended from one original tree, and apparently able to reproduce indefinitely.

The Pando aspen clone in Utah is thought to be 80,000 years old; some think it could be ten times older. It’s hard to guess age, as counting tree rings isn’t much help, and a long-term study would have had to start when humans were still mustering to leave Africa.

I remember, from sometime very long ago, a short sci-fi story about a sentient  long lived tree on a planet somewhere that needed a sentient host to reproduce itself.  It was stuck on a planet with no sentient life until a human explorer landed.  The deal was, if the astronaut accepted the host, he would live a long, disease free life, but ultimately have to settle down to become another tree...

I wish I could find that story again.