Reading Trees

When asked to draw a tree, most of us would instinctively depict a trunk, some branches, a canopy, and perhaps a modest network of roots. During my first courses in the Master of Science in Landscape Architecture at ETH Zürich, I developed a deep interest in observing trees, reading their past and potential future development, and translating this information into drawings. Through the MScLA program, courses like the module ‹Plant Ecology› and ‹Cartographies of Living Systems› – an elective course taught by Teresa Galí-Izard – provided the students with a base of dendrological knowledge and a methodology for analyzing trees through drawing.

Reading a senescent tree in Zurich; in blue, the súppliants.

This approach to studying trees is grounded in an understanding of their physiology, focusing on their primary and secondary growth. It starts by reading the tree’s natural logics of development through the location of meristems and their branching patterns and directions. Botanists like Hallé, Oldeman and Tomlinson were pioneers in classifying the way these parameters are expressed and combined, developing what they termed «tree architectural models.» These models represent ideal forms of growth, typically observed in trees growing under optimal conditions – such as in rainforests – that have not suffered significant disturbances.

Reading trees from a painting

Trees, however, rarely grow under perfect conditions. Factors such as water stress, pests, accidents, aging, or pruning, often disrupt their genetically determined growth patterns. As a survival strategy, the tree will then modify its development to adapt to the new challenges, with responses that vary depending on the type and degree of disturbance. By reading an actual tree through the logics of its species’ architectural model, it is often possible to distinguish between regular growth of lateral meristems, which forms branches, and a tree’s adaptive response through the activation of dormant meristems. Botanist Christophe Drénou termed such reactive growth «suppliants» and developed a tree assessment methodology based on the identification of these survival responses through diagrammatic drawings: the Archi method.

Field sketch of the remaining Platanus hispanica in a street in Barcelona, Spain. September 2024.

Observing trees through this lens gives us clues about their past and present conditions and helps us design accordingly. For instance, identifying clusters of «suppliants» or finding irregularities in the secondary growth might inform us about the tree’s reaction to management practices, traumatic events – such as transplantation – or ongoing stress conditions. Moreover, certain reactions of the tree’s aerial biomass could be prompted by underground disturbances and could indicate an unhealthy development of the root system, allowing us to act on otherwise invisible deficiencies.

A methodology for observing and understanding trees gives us essential information about their past, present, and potential future growth dynamics and helps us as landscape architects in making informed decisions when designing environments with—and for—trees.


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