The Pietraporciana Nature Reserve occupies the top, the northern slope and part of the southern side of the hill of the same hill (847 metres), on the ridge that separates the Val d’Orcia and the Valdichiana between Chianciano Terme and Sarteano.
An unusual low-altitude beechwood grows in the reserve, benefitting from the cool air and humidity in the upper part of the northern slope of the Pietraporciana hill, sheltered by limestone bluffs that emerge at the summit. The striking beechwood extends between 750 and 850 metres in altitude and is a small part of a larger forest that grew throughout the area thousands of years ago.
Centuries-old trees cling to the rocky slope, often covered in moss at the bottom of the trunk. Although the beech is the dominant species, there are also numerous examples of Turkey oak, European and hop hornbeam, sycamore, acers and checker trees.
Two rather rare scrubs grow here: belladonna, a bush with poisonous blue berries, and the broad-leaved spindle, as well as the very rare martagon lily.