The koa tree of Hawai'i, an acacia...

The koa tree of Hawai'i, an acacia ... is one of my favorite trees.  The forests on the upper slopes of the north side of Mauna Kea include many examples like the one at right, especially just west of the memorial marking the spot where botanist David Douglas died.  I find these riparian koa examples to be hauntingly beautiful.

I was very surprised to read this morning that a strikingly similar tree grows on a remote island (Réunion) in the southern Indian Ocean, east of Madagascar – 11,000 miles from Hawai'i.  Then I read something even more surprising: by means unknown, the trees on Réunion are descended from a single individual (presumably a seed) from Hawai'i.  The most likely mechanism that anyone's thought of is a seed somehow hitching a ride on a bird, but that's speculation.  You might think of a seed floating there, but koa seeds soaked in salt water won't germinate, so that's not likely to have been the mechanism.

The linked article calls it a “giant fluke”.  I'll call it another fine example of the power of time – even a very low-probability event becomes likely if enough time passes...