Around Oaxaca in the highlands of Mexico there is a form of maize that reaches six metres in height, with orange, finger-like roots that grow out of the stem and hang in the air, oozing mucus. It seems bizarre, but in the mucus live hundreds of kinds of bacteria that ‘fix’ atmospheric nitrogen and thereby help to fertilise the plant. The crop is known locally as ‘olotón’ and for centuries it was the main staple of the Mixe people, a tribe that Hernán Cortés in the 16th century failed to conquer because their territory was too inaccessible and rocky. Olotón was able to withstand drought, heat and cold to flourish, with the help of its on-board bacteria, in very poor soil.

But olotón has barely survived the ravages of modern, corporate-led commerce and high-tech agriculture. Just a few farmers keep it going for reasons that may seem simply aesthetic or romantic, yet in truth are visionary. Many thousands of varieties of crops and breeds of livestock are being lost