Bernal Diaz, author of the only eye-witness account of Cortez' conquest of Mexico writes:
"I sowed some orange pips near another of these temples ... The trees came up very well, for when the papas saw that these were different plants from any that they knew, they protected them and watered them and kept them free from weeds. All the oranges in the province are descendants of these trees."Interestingly enough Diaz scratched out this passage from his manuscript thinking it was of no consequence.
From Cynthia D. Bertelsen's book "Mushroom, A Global History" I quote from page 44:
"Ethnographic studies indicate that many of the ancient cooking practices can still be found in isolated Italian villages... where the older woman within the community fry field mushrooms with sweet green peppers"A sweet pepper is of course in the capsicum family, a plant from the new world.
Below is a table copied from William Balee's fabulous book on Ka'apor ethnobiology "Footprints of the Forest". The Ka'apor practice swidden agriculture in the Eastern Amazon, the kind of people often portrayed as isolated and living according to ancient ways. Here is a list of the old world plants and trees in their gardens, 22 in all.
The Columbian exchange is final and has touched even the most obscure corners of this planet.