**1. Introduction**

This article aims to question the role of vegetation in the understanding and design process of the city through the morphological characterization of different homogeneous areas extracted from the urban fabric of the city of Lisbon. The approach to each urban segment is based on a morphological decomposition process of urban systems and elements. This enables the understanding of the complexity of each urban unit from the reading of its public and private components. The reading of the private city is made from the interpretation of the built fabric and the elements that structure it, such as urban blocks, plots, buildings and courtyards. The public city, as addressed in this article, is understood from the reading of the urban layout as a bi-dimensional representation of the city's public spaces and elements, such as streets, squares and vegetation as a variant and leading element of this exercise.

By taking vegetation as an element of urban morphology, this work challenges the most common morphological approaches to the city that invariably relies on stabilized and tested methodologies based on different schools of urban morphology such as the Italian, Anglo-Saxon, and French ones.
