The garden of the Arese Borromeo Palace is open to the public and represents a sort of country retreat in an urban context strongly anthropized and that has lost much of the old agricultural destination enjoyed by “palace” life in the past.

Strolling through the pathways, here one can enjoy the coolness and shade that the trees offer the visitors. The undergrowth provided by the majestic lime, oak and horse chestnut trees and some specimens of sycamore (Acer pseudoplatanus) and field maple (Acer campestris) grow naturally in the park.
Field maple (Acer campestris): grows spontaneously throughout Italy and is one of the most familiar trees in our landscape. In the past, the maple was used as a garden plant; in fact it is left to grow without pruning and is usually isolated. The tree can grow to considerable heights. This particular species of maple is notably appreciated for the shade it provides because of its dense and compact crown. It is also used to form hedges since it supports pruning very well, even intense pruning.
In the park of the Arese Borromeo Palace, some isolated specimen of the field maples can be found along the outer avenue of the white hornbeam trees that run parallel to the wider part of the garden. The branches of the maple are different from the light-grey ones of the hornbeam; in fact they are cinnamon coloured towards the apex of their dense crown. Because of its compact and beautiful wood-grain colour, in the past, it was used for cabinetry and inlay.
Observed closely, the leaves of the field maple have very long petioles, opposite and small with three main lobes that have rounded edges and two lower lobes that are smaller. In the summer, they have a green, opaque colour on top and downy below, while in autumn the leaves become yellow-amber in colour.
The small yellow-green flowers form erect tight bunches, while the fruits have two, green, winged capsules gathered together (achene) with the wings disposed almost in a straight line, often tinged with pink.
In early autumn, field maple leaves have golden red tones in parks and gardens of leisure and in the past, this sudden change in colour into tones of vermillion was given a menacing significance and for this was dedicated to Phobos, the god of fear, son of Ares. The name acero/maple is derived from the Latin word acer (sharp, barbed) referring to the maple leaves platanoides that have five lobes with an uneven outline.
In the wooded garden belonging to the Arese Borromeo Palace are some specimens of Acero di monte/sycamore maple (Acer pseudoplatanus) that have a wide crown and a canopy, and a smooth, pale-yellow bark that blends into grey. Unlike the field maple, the leaves have a width of 16 cm, are dark green on top and grey-green at the bottom and are five lobed. The leaf edges are deep and sharp with irregular serrated margins.
A fungus called Rhytisma acerinum disfigures the leafy branches of the tree but does not harm them. Galls may appear on the leaves, which are formed as a reaction to the bite of the Phytoptus insect.
Flowers appear around April and gather on drooping yellow-green clusters that form after the leaves appear while its gray and cracked bark becomes pinkish-brown over time. By notching the bark of the tree, a particular sap is drawn out, which in the past was considered suitable to fight scurvy and was also used, after fermentation, to produce an alcoholic beverage.
This medicinal characteristic has been lost today but the maple trees of Arese Borromeo Palace are plants that deserve to be observed with care, even only to compare them with the maple trees in the surrounding gardens of Villa Cusani Tittoni Traversi in Desio.