A conversation with Alexander Olson (independent scholar, British Columbia, Canada) about the secret lives of olive trees and oak trees in Byzantium. Contrary to what you may think, these were not cultivated consistently in the Mediterranean ecosystem of the Middle Ages; their uses to the human population fluctuated over time, giving the trees a history of their own, albeit one shaped by that of the people around them (and vice versa). The conversation is based on Alex's fascinating book, Environment and Society in Byzantium, 650-1150: Between the Oak and the Olive (Palgrave Macmillan 2020).