The exhibition is a journey through twenty-two stories of trees, virtuous metaphors distributed over time and geography, which show, among other things, how to entrust the saving mission of architecture is not really such a new phenomenon.

Just as plant cosmetics is not a new phenomenon, the practice of hiding the building mass behind the green about which Frank Lloyd Wright ironized: "A doctor can bury his mistakes, but an architect can only advise the customer to plant vines".

For some years, every time we talk about architecture and trees, we have witnessed a kind of uncritical sermon on the return to nature that forgets a fundamental aspect: that trees are living creatures, architectures themselves, often incoercible to the reasons of those who want placing them in a project neglecting their nature and specific properties. And, above all, forgetting that they are uncontrollable, as evidenced by the ficus grown next to an Oscar Niemeyer hotel in Brasilia to match the master's architecture in size.

In the words of Gallanti, "there is an almost ideological vision, apparently unprecedented, of the relationship between trees and architecture, which gives rise to a myriad of ready-to-use solutions and a wave of self-proclaimed gurus and experts".

The exhibition does not want to indicate a main road, even if a common thread inevitably emerges from the choice of the curators that binds the virtuous stories. They are those in which greenery and design live in symbiosis, almost interpenetrating. Where trees become columns or windows and not just the tool for an ecological conscience wash. Here then is the holiday home on the sandy beach of Cap Ferret signed by Lacaton&Vassal where nine pines almost join their branches to surround the volume, preserving the shrub vegetation under their foliage. Or the sketches by Alvaro Siza for a house in Cape Verde where the line seamlessly blends the greenery and the building. Or, to go back to a classic, the Crown Hall at the IIT in Chicago designed by Van der Rohe and Caldwell as a blend of architecture and landscape.

“A new phenomenon” explains Gallanti “is the greater attention paid to the existing green heritage, rather than to the need to plant new trees. Many planners have understood the importance of preserving. One of the reasons is that older trees absorb CO2 better”. At the same time, a more careful study of botany allows us to better orient some choices: "When deciding which trees to plant in the city, so far the male specimens have been preferred more often, because they do not produce the fruits that would fall on the street making the trees grow. maintenance costs.

The downside is that male flowers produce pollen, causing seasonal allergies to grow exponentially. In the short term, the benchmarking between maintenance costs and those for work interruptions due to allergies could become decisive in planning what types of trees we will have in our cities”.

Inevitable, speaking of trees and architecture, to spend a reflection on Bosco Verticale, even if the project is not included in Arboretum. "With that architecture, Stefano Boeri put the environmental theme on the table in an effective way, to the point of replicating the model in the world, while other architectures that follow the same principle have become targets of easy irony. Of course, we architects are very good, with our cynicism, to take it out on those who have crossed a finish line, but perhaps the truth is not in the uncritical celebration as it is not in the vitriolic criticism. A serious analysis would be needed to tell us, in ten or twenty years, what that project really was for ".