Leonardo transformed the hall into a complex arboreal pergola, by painting the intertwined branches of sixteen mulberry trees embellished with ropes.

On the walls he painted sturdy trunks planted on a high embankment, on which he created monochrome roots, rocks and scenery. The choice of the solid and sturdy mulberry trees or black mulberry, was undoubtedly a reference to the nickname of Sforza, who was known as il Moro in reference to both his dark complexion and his role in the spread of the mulberry tree plantations, on which Lombardy’s flourishing silk production was based. Furthermore, in terms of the symbolism of the plant, also referred to as sapientissima omnium arborum, it was probably first used to describe the Duke of Milan by the court poet Bernardo Bellincioni, who in so doing, wished to celebrate il Moro’s political wisdom and the stability of the Duchy under his rule.