The Selective Criteria for Trees in the Avenida da Liberdade,Lisbon 1882

Abstract

This article explores the historical context and decision-making process behind the selection of tree species for Avenida da Liberdade, Lisbon’s iconic boulevard constructed in the late nineteenth century. The City Council’s decision to establish a grand avenue was influenced by Lisbon’s modernization, inspired by Parisian boulevards, and driven by the historical circumstances, particularly the reuse of trees from the Passeio Público, rather than the theoretical norms of the time that favored uniformity in tree species for their practical and visual benefits. The article examines three key aspects: the conception of the avenue as a symbol of progress, the work of the appointed committee and its decision-making influenced by the period’s scientific and artistic theories, and the specific tree species chosen, highlighting the socio-natural factors that influenced their selection. It argues that the choice of species, largely overlooked in historiography, reveals a nuanced interplay of practical constraints and urban planning ideals.

Introduction

On May 4, 1882, the city council appointed a committee to determine which species should be planted on the new boulevard of Lisbon—the Avenida da Liberdade (Liberty Avenue). All botanical and artistic nineteen-century conveniences advise that a single species of tree should be cultivated in these kinds of public avenues because, with similar trends in vertical growth and crown development, individuals do not harm each other. However, this was not followed in the Lisbon boulevard, and this article addresses the criteria behind the choice of its tree species, taking into consideration both the Parisian role model, the specialized literature, the region’s biophysical conditions, and the political, social, and economic circumstances in which the Avenida was made.

In Portugal, the modernization of the state and the nation had begun when the Liberals came to power in 1834, after a civil war. Ever since the Liberals came to power, they had been striving to outline a general plan for the rebuilding and development of the city, which was still struggling to recover after the earthquake. The City Council underwent reorganization in 1840, and the Department of Gardens and Green Grounds was formed, highlighting the importance that greening the city held for the Liberals. In 1851, the dawn of a new political era in Portugal, known as the Regeneração (Regeneration), marked a new commitment to material progress, which spurred Lisbon’s transformation. ¹

The Liberal administration took on the responsibility of maximizing tree planting across the city. As a result, the number of trees in Lisbon grew from 2,791 in 1858 to approximately 20,000 by 1900. In 1858, there was almost no record of trees planted along streets, with some exceptions, amounting to only ninety-six trees out of 2,791, which were mainly distributed across gardens, squares, and plazas. ² During the second half of the nineteenth century, however, the Department of Gardens and Green Grounds took on the responsibility of planting trees along streets and avenues, keeping pace with the city’s expansion. ³

Although the modernization of the city had already begun, it was only in 1864 that a general plan for the improvement of the capital was drafted. However, little progress was made until 1876, when construction activities resumed. By 1879, the situation had significantly changed. Before the creation of the Avenida da Liberdade, another major artery had already been planted with aligned acacias, elms, and hackberries—the Avenida 24 de Julho. ⁴ This avenue, laid out parallel to the Tagus River, was designed to improve connectivity between Lisbon’s historic center and its western gateways, particularly toward Cascais.

By this time, the main axis of the city’s green infrastructure—the Avenida da Liberdade—was already taking shape. In fact, Lisbon’s northward expansion had been anticipated by the creation of the Passeio Público, ⁵ the city’s first public garden, situated just north of Restauradores Square. Although originally envisioned in 1764 by Sebastião de Carvalho e Melo, better known as the Marquis of Pombal, the garden was only fully realized by the Liberal government between 1834 and 1840. ⁶

The idea of constructing the Avenida da Liberdade to connect Lisbon’s historic center to its northern exit dates back to the 1850s. Over the following decades, various proposals were put forward, but progress was repeatedly delayed due to political and financial constraints. In 1876, however, the project was formally incorporated into the general plan for the improvement of the capital. Construction of the new avenue began in 1879, and at the time, it was planned to start only from the northern edge of the Passeio Público. The dismantling of the garden itself was not yet envisioned. It was only around 1882 that this would ultimately occur, allowing for the full realization of Lisbon’s grand boulevard.

The boulevard had become the hallmark of nineteenth-century urban modernization, inspired by the transformation of Paris under Napoleon III (1808–1873), Baron Georges-Eugène Haussmann (1809–1891), and Jean-Charles Alphand (1817–1891). ⁷ The Parisian boulevards played a pivotal role in urban renewal by modernizing infrastructure, improving traffic flow, enhancing hygiene and public health, and serving as iconic public spaces that fostered social interaction. ⁸

The influence of French models on the modernization of Lisbon is unmistakable. However, when it comes to the development of the city’s green infrastructure, two key figures stand out. On one hand, there is the city councilor Francisco Simões Margiochi (1848–1904), who, between 1872 and 1875, established a specialized library within the department. Analysis of this collection has revealed that it consisted largely of French-language books promoting the picturesque garden style popular in France at the time. ⁹ On the other hand, in 1874, the engineer Frederico Ressano Garcia (1847–1911) joined Lisbon’s City Council, having graduated from the École des Ponts et Chaussées in 1869 and witnessed Paris’s urban renewal firsthand. While the ties between the Lisbon municipality and the Préfecture de la Seine were broader and more institutional, these two individuals were especially instrumental in facilitating the circulation of the French urban model to peripheral European capitals such as Lisbon.

Focusing on the 1882 episode in which a committee was appointed by Lisbon’s City Council to select tree species for the newly planned Avenida da Liberdade, I argue that their choices were shaped less by abstract theoretical, aesthetic, economic, or ecological criteria and more by specific historical constraints. While the committee was undoubtedly familiar with contemporary literature recommending the use of a single tree species for formal urban avenues, they faced the practical necessity of reusing as many trees as possible from the dismantled Passeio Público—a decision driven in part by an emerging sensitivity toward tree preservation and growing resistance to indiscriminate felling. In addition, there was awareness within the City Council of the need to choose species suited to Lisbon’s climate, a concern explicitly voiced by some of its members. Finally, aesthetic considerations also played a role, particularly the appeal of exotic, colorful trees that could frame and enhance the visual experience of the surrounding architecture. The resulting selection, therefore, reflects a layered negotiation between ideals and limitations, and a response to local material realities rather than a pure application of imported urban models.

Although the history of Lisbon, in general, has been extensively studied from the perspective of urbanism and architecture by art historians, ¹⁰ only recently, studies at the intersection of the history of science and garden and landscape studies have highlighted the role of the Liberal movement in greening Lisbon, the influence of the French model in Lisbon nineteenth-century garden design, the development of public gardens, the contributions of both politicians and experts at the Lisbon City Council, as well as the major task of planting tree-lined streets. ¹¹

The Avenida da Liberdade, in particular, has recently been examined by architects, who have studied Ressano Garcia’s role in Lisbon’s urban planning, from the launch of the Avenida to the development of the avenidas novas in Picoas, as well as the design and typology of the buildings, which diverged from the French model due to the absence of regulations on building height and façade appearance, unlike in the French case, in which everything was regulated. ¹² Historians of architecture have also addressed the sociability that transforms the avenue into a boulevard. ¹³

Art historians’ analyses have traditionally contrasted the Avenida with the Passeio Público, interpreting them as symbols of two opposing political regimes: the Ancién Régime and Liberalism. ¹⁴ However, this narrative is far more complex than it suggests. ¹⁵ As previously noted, this dichotomy overlooks another key player—the Estrela Garden—the Liberals’ flagship project, which had been diverting funding and labor away from the Passeio Público since its inauguration in 1852. In fact, it was the Estrela Garden, not the future boulevard, that competed most directly with Lisbon’s first public garden. ¹⁶

The selection of tree species for Avenida da Liberdade has been entirely overlooked in historiography, despite being a particularly relevant topic in light of current climate change, as trees play a vital role in cooling urban spaces and mitigating temperature rise.

The role of trees in shaping urban landscapes has only recently become a significant subject of historical study. Trees are increasingly recognized for their non-human agency, serving as socio-natural structures that interact with human society. Their impact is explored through concepts like arboriculture, tree-places, and the ethical issues surrounding their conservation, highlighting how specific locations are shaped by trees. ¹⁷

While trees in places such as orchards, cemeteries, and squares have been studied, the focus on trees along boulevards, streets, roads, and avenues has been less explored. Nevertheless, the Britain case can be considered an exception as the history and management of trees in Britain have been examined in terms of their cultural and environmental integration into cities. Historical periods such as the Victorian are noted for their emphasis on urban green spaces and street tree planting. ¹⁸ More recently, attention has turned to the politics that enabled their creation, as well as to their ongoing conservation and management, particularly as trees are now recognized as vital agents in cooling urban environments and, in doing so, contributing to social justice in a time of accelerating climate change. ¹⁹ As trees play active roles in shaping the environment, influencing microclimates, supporting biodiversity, and even affecting human interactions with the space, this choice is of the utmost importance, especially because trees operate on ecological timescales that differ from human planning and decision-making cycles. ²⁰

Due to the importance of the topic, it has been addressed from contemporary perspectives of ecology, urban forestry, urban studies, and sustainability, ²¹ but remains a neglected topic from the perspective of urban history of science.

In order to unfold my arguments, I have divided this article into three parts. The first tackles the rise of an idea to make a great avenue and how it gained the shape of a boulevard. The second part addresses the committee appointed by the Lisbon City Council and the circumstances laying behind the decision and the theoretical production on tree species for tree-lined streets of their time. The third part focuses on the tree species chosen for the boulevard and their characteristics in order to understand what criteria prevailed for their choice. I decided to characterize and analyze the trees selected by the committee in the light of nineteenth-century literature and praxis for urban plantings to understand what might have been behind the committee’s choice.

Beyond Circulation: The Creation of Lisbon’s Iconic Boulevard

The idea of creating a boulevard evolved over time. It was not a project that was designed and immediately carried out. It has a history spanning more than two decades, from the idea of constructing an artery to link Lisbon’s historic center to its northern gate into the iconic boulevard of Lisbon.

On June 3, 1859, for the first time the idea of making a great avenue in Lisbon was launched at the Lisbon City Council. The Mayor Júlio Máximo de Oliveira Pimentel (1804-1884) argued that studies should be started to decide on the construction of an avenue to link Lisbon’s historic center with the northern gate of the city, starting at the top of the Passeio Público and ending at São Sebastião da Pedreira, which was by then near the private Park of São Sebastião da Pedreira (now the Calouste Gulbenkian garden). In view of this, he orders the “study of the opening of a large street or alameda,” without calling it yet boulevard. ²² Until the nineteenth century, there were no alamedas in Lisbon—broad, tree-lined streets (the term derives from álamo, meaning poplar tree in both Portuguese and Castilian)—unlike in Spain, where such spaces had existed since the early modern period, as exemplified by the Alameda de Hércules in Seville (1574). ²³ Alamedas might be interpreted as forerunners of boulevards, but not in Portugal, as there were no alamedas in Lisbon until the Liberals came to power, probably due to the limited Spanish influence in the country following sixty years under the Spanish Philips dynasty (1580-1640), and the Restoration War (1640–1668), which had pitted the Portuguese against the Spanish for twenty-eight years. When Pimentel used the term alameda to refer to the major thoroughfare that was to be opened to connect the historic center with the city gates, there was not yet any intention of creating a boulevard in the French sense.

In the 1850s, the idea of building a major thoroughfare began to take root. The idea did not proceed in that moment but some seeds germinated. The facts are known, and there were many advances and setbacks due to political and financial reasons. Here, I will focus on highlighting some of the key steps that ultimately led to the beginning of the Avenida’s construction. Hence, on March 5, 1863, four years after Pimentel’s suggestion, the councilor Severo de Carvalho made another proposal, in which for the first time the dismantlement of the Passeio Público was envisioned. ²⁴ The third significant proposal was made in 1870 by Joaquim Tomás Lobo d’Ávila (1819-1901), Count of Valbom, by then Minister of Public Works, resuming the idea of the construction of an avenue beginning at the northern gate of the Passeio Público. On May 21, 1874, at the Lisbon City Council, Margiochi presented his proposal for the “abertura de uma grande artéria” ²⁵ (opening of a big artery). Despite the various contributions, Margiochi will not let the idea/proposal of opening this avenue be credited to others, to the point that he will write a book in which he essentially claims the “parenthood” of Avenida da Liberdade. ²⁶

By the late 1870s, plans for the construction of the Avenida da Liberdade began to gain momentum. The French-style urban renewal reached Lisbon, largely due to the growing influence of Ressano Garcia. In 1876, legislative measures were enacted to secure funding and authorize the necessary expropriations for the project’s realization. Moreover, adjustments to the legislative and regulatory framework redefined the relationship between the president of the Lisbon City Council and the chief engineer of the Technical Department. These changes streamlined the decision-making process and facilitated the implementation of the urban renewal plan.

Finally, the idea of introducing a symbol of urban modernity—the boulevard—began to take shape. The City Council sought to create such an avenue because Lisbon lacked one, and this quintessentially Parisian feature was seen as a vital stage for bourgeois sociability. In this context, Ressano Garcia’s approach stood out. As the City Council’s chief engineer, he presented a plan that incorporated the existing Passeio Público as the initial stretch of the new avenue, significantly widening the traffic lanes (Figure 1). He also placed the project within a broader vision for the city’s northward expansion.

Figure 1.

Lisbon. Drawn by W. B. Clarke. London. 47 Paternoster Row: Baldwin & Cradock, 1833. BNP Biblioteca Nacional de Portugal (National Library of Portugal), C.C. 595 V.

From the outset, two contrasting visions for the Avenue shaped its development. Public opinion and many council members saw it as a great artery starting at the end of the Passeio Público in Rossio and leading to the northern exit of the city. However, the Technical Department, led by Ressano Garcia, viewed it as the initial phase of a comprehensive green infrastructure project. ²⁷ He aimed at addressing the city’s growing need for better north-south connectivity, and following the latest French trend, he envisioned the beautification of the city with the construction of a boulevard that would be a symbol of modernity and material and social progress. This latter vision was not initially planned but gradually gained traction and evolved over time.

On October 12, 1877, councilor Rodrigo Afonso Pequito requested clarifications about the width of the avenue. The chief engineer Ressano Garcia, head of the Technical Department, defined that the new avenue would have the same width as the Passeio Público, including the side streets. In addition, he claimed that it should be developed “as a boulevard with tree-lined pathways and gardens, modeled after the grand, monumental French thoroughfares but at a smaller scale,” as it would have no more than 90 m width and 1,200 m length. ²⁸ The status, scope, and scale of the avenue were gaining shape.

The time between 1877 and 1879 was marked by intense activity. The Regulations of the Technical Department facilitated the success of urban renewal as it empowered the roles of the President of the City Council, José Gregório da Rosa Araújo (1840-1893), and of the chief engineer of the Technical Department, Ressano Garcia.

The transformative potential of the boulevard for Lisbon was formally recognized on July 18, 1879, when the Municipal Works and Improvements Committee extolled its many advantages. They described it as

an improvement that greatly benefits not only the beauty of the city of Lisbon but also public wealth, as the opening of this grand artery will certainly lead to new constructions and new workers’ neighborhoods, thereby contributing to a reduction in house rents, and because the hygiene of cities always benefits from the opening of new and spacious streets and improved communication facilities. ²⁹

On July 21, 1879, the Lisbon City Council unanimously approved the project for the construction of the first section of the avenue, which would extend from the current Passeio Público with its full width, ending in a circular plaza with a 200-m diameter (Marquês de Pombal Square) from which streets with a length of 30 m would radiate: one toward Largo do Rato, a wider one toward the new Penitentiary building and enclosed by walls, another leading toward Campo Grande and another to Benfica. ³⁰

A month later, the name of the Portuguese boulevard was decided: Avenida da Liberdade. ³¹ An appropriate designation, not only because it would immortalize its mentors in what would become the city’s main axis but also as Lisbon could now expand northward freely, without barriers, in an open, monumental, and civilizing manner, whose possibilities now extended far beyond the Restauradores (Figure 2).

Figure 2.

Plan of Lisbon, in “O Século,” Lisbon, 1909. BNP, C.C. 1323 R.

The boulevard became a symbol of modernity and progress in the Portuguese capital at that time. However, it cannot be said that Lisbon fully imported the Haussmannian model of the boulevard. The political, legal, and socio-economic context of the Second Empire fostered the urban renewal of Paris to such an extent that it could not be easily reproduced elsewhere. Sixty percent of the old Paris was erased to give birth to “the city of light.” Moreover, Haussmann ensured the adherence to the building-street relationship, which was the foundation of his plan. This relationship was based on three main aspects: hierarchy, alignments, and standardization. Regulatory architecture asserted itself strongly, and the ornamentation was very refined, even if the effort to control public space diminished as the urban grid became more secondary. ³²

Therefore, the “Portuguese adaptation” of the importation of the Haussmannian model is marked by fundamental differences. Contrary to the French archetype, in Lisbon, there was no regulatory architecture, and no specific law defined rigid parameters for the construction of the built mass surrounding Avenida da Liberdade. Moreover, in Lisbon, the intention was to expand northward, where the characteristics were still markedly rural; hence, the level of destruction and expropriation cannot be compared. Unlike in Paris, no medieval, Renaissance, or Baroque district in Lisbon was erased or cut through by a boulevard. There was a gradual adaptation to the idea of changing the existing urban fabric. In 1881, the expropriation of the Circo Circe and some buildings in Praça da Alegria de Baixo were the only changes to the pre-boulevard urban fabric, until the dismantlement of the Passeio Público.

This decision was not predicted when the construction of the Avenida began. However, since 1875, the construction of the Monumento dos Restauradores (Monument to the Restorers) was underway, and the pressure to remove the fences of the public garden for its inauguration in 1883 was significant, as the obelisk was to be located within its grounds (Figure 3). This was decisive to reinforce the need to dismantle the Passeio Público. By evoking this issue, Rosa Araújo succeeded in getting the majority of the city council to vote in favor of the proposal presented by the Committee for Municipal Works and Improvements to dismantle the Passeio Público, with only two councilmen opposing: the Viscounts of Rio Sado and Carriche, the latter being the councilor of the Department of Gardens and Green Grounds. ³³ Nevertheless, we understand that this matter served as a pretext, and only that, since the actual inauguration of the Monument of Restorers would only take place in 1886. In fact, the Passeio Público was always highly contested: from foreign critics in its early days to liberals who later constructed a narrative linking it to a different political regime, conveniently overlooking the fact that the garden had, in reality, been built by them in the 1830s. The public’s fondness for the garden was not enough to save it. The vision and desire for modernity held by liberals such as Margiochi and Ressano Garcia ultimately prevailed. ³⁴

Figure 3.

The Monument of the Restorers, O Occidente-Revista Illustrada de Portugal e no Extrangeiro, vol. 29, no. 980 (March 20, 1906), 60.

The construction of the Monument to the Restorers would hasten the decision to demolish the Passeio Público in 1882, a move that had not been previously considered. The railings were removed in the third quarter of 1882, and in 1883, the southern lake along the central street began to be demolished to accommodate the aforementioned monument. ³⁵ The last phase included the demolition of the cascade that still stood on the northern bottom, which was justified as it undoubtedly paved the way for “one of the most important projects that the Lisbon City Council” had undertaken. ³⁶ Thus, the last structures of the old Passeio Público disappeared. The boulevard had gained its momentum. Along this process, in 1882, a committee was appointed by the Lisbon City Council to identify the best tree species for the Avenida and surpass the challenges posed by such plantings.

The Committee Appointed for Selection of the Boulevard’s Trees

The boulevard’s design incorporated vegetation, which not only enhanced its aesthetic appeal but also improved air quality and created inviting spaces for leisure and relaxation. On May 4, 1882, the Lisbon City Council appointed a Committee composed of politicians, gardeners, agronomists, and botanists, to decide which species of trees should be planted along the new avenue. Among its members were the councilor of the Department of Gardens and Green Grounds, the Viscount of Carriche; the chief gardener of the municipal nurseries, Jacob Weiss; the master gardener of the Department, João Francisco da Silva; former councilor Margiochi; and the chief gardener of the Lisbon Polytechnic School, Jules Daveau. ³⁷ Through the lens of the urban history of science, which argues that “making the city” involves knowledge produced by politicians and other actors such as doctors, engineers, and architects, ³⁸ this case highlights how nineteenth-century Lisbon’s green infrastructure also relied on unexpected contributors, including gardeners, agronomists, and botanists. ³⁹ This moment of selecting tree species to be planted on the boulevard is one of the most relevant cases of the participation of such a diverse range of actors.

Margiochi was a forward-thinking figure in nineteenth-century Lisbon, making significant contributions to agriculture, horticulture, and public service. As a councilor of the Department of Gardens and Green Grounds between 1872 and 1875, Margiochi earned recognition for creating specialized library resources for urban planning. His expertise in agronomy was instrumental in urban greening efforts, notably through his work in planting trees throughout the city and transforming neglected public spaces. His expertise and leadership in Lisbon’s Municipal Council secured him recognition and throughout his life he collaborated with the municipality. Beyond his municipal roles, Margiochi founded Portugal’s first gardening course at Casa Pia, championed the protection of green spaces, and established the Royal Horticultural Society of Portugal. ⁴⁰

The 1st Viscount of Carriche, Isidoro Tomás de Moura Carvalho (1825–1887), served as councilor of the Department of Gardens and Green Grounds of the Lisbon City Council for nearly a decade, from 1878 to 1885, making him the longest-serving councilor in that role. During his tenure, he faced several challenges, such as financial difficulties and the growing influence of the Technical Department, as well as the prominence of Ressano Garcia, including in matters related to green spaces. ⁴¹

The gardener João Francisco da Silva dedicated his entire career to the Department of Gardens and Green Grounds, progressing from apprentice to head gardener. Despite the lack of formal gardening education in Portugal at the time, he honed his craft through practice and self-education: studying specialized literature, traveling to the Potager du Roi à Versailles for guidance, and developing his skills in landscape design. Over his more than thirty years of service, Silva advocated for fair compensation to support his professional development and the acquisition of necessary resources. His commitment to public service, paired with his technical and creative acumen, positioned him as a pioneer in municipal gardening, bridging the roles of horticulturist, landscape manager, and educator. ⁴²

The French Jules Daveau (1852-1929) began his career as a student gardener at the Muséum d’Histoire Naturelle in Paris, the only school of horticulture in France at the time. In 1875, Daveau was sent to Cyrenaica to search for the ancient plant Silphium, a plant of great value to the Egyptians and Greeks. Later, as a director of botanical gardens in Lisbon, Daveau made substantial contributions to the botanical knowledge of the region, including developing a phytogeographical map of the country. His meticulous work brought him recognition in the intellectual circles of Portugal, but due to personal and family considerations, he returned to France in 1894 to become the curator of the Botanic Garden and Herbarium of the University of Montpellier, ensuring that the botanical collections in that city gained a prominent place among Europe’s great national collections. ⁴³

Jacob Weiss was a Swiss gardener who came to Portugal to work for the Dukes of Palmela. Later, he collaborated with the Department of Gardens and Green Grounds and became head of the nursery of Picoas. In recognition of years of collaboration, he donated his private library to the specialized library of the Department of Gardens and Green Grounds in 1898. The donation included thirty-four volumes of Revue Horticole spanning from 1841 to 1897, as well as books by Vilmorin and Andrieux, Nicolas-Charles Seringe, Georges de Chambray, and Jules Daveau, among others. All the titles were in French and Portuguese, with a predominance of French works. The absence of German or Italian literature was surprising, given his Swiss background and the country’s multilingual nature. ⁴⁴

The main cultural influence in nineteenth-century Lisbon was French. During this period, in terms of garden art, a stronger influence of the English landscape garden can be observed in Porto, Sintra, and the islands of the Azores and Madeira—primarily due to specific individuals who introduced this aesthetic to those regions. ⁴⁵ But in Lisbon, the influence was mainly French, as evidenced by research conducted on the Department of Gardens and Green Grounds, particularly the composition of its specialized library, with 68 percent of the books in French. Notable among them are Alphand’s Les Promenades de Paris (1867-73), the journal Flore des Serres, Revue Horticole, and the well-known works of Gabriel Thouin, Rudolph Siebeck, Pierre Boitar, M. Boncenne, Joseph Decaisne, Jean-Marie Morel, Charles Naudin, Baron Ernouf, Élie Abel Carrière, Jean Lachaume, Édouard André, and Georges Delchevalerie, among many others. Moreover, it became clear that these books were part of the closed circle of French picturesque editors and authors, promoted through personal and commercial relationships between members of Lisbon City Council, such as Margiochi, and the Rothschild publishers, who published nearly all these works and advertised new releases in every delivery to the Lisbon Council. ⁴⁶

This group of experts was totally aware of the theoretical production and literature conveying all botanical and artistic conveniences. In the case of the Lisbon City Council, the library’s extensive collection makes it impossible to focus on the reception of a single book. Instead, we must consider the impact of a wide array of texts, most of which collectively disseminated the theory and practice of the French picturesque style in garden art. Moreover, the extensive literature of the time helps us understand the technical and scientific complexity of these plantings. As with many other matters, Alphand’s Les Promenades de Paris (1867-73) served as a reference regarding tree planting techniques and tree species’ selection. The issues that Parisian landscape architects and gardeners encountered, and the solutions detailed in the book, were useful for Lisbon City Council professionals, who faced similar challenges.

Reception theory typically focuses on how a specific text is read and interpreted by individual readers or groups. ⁴⁷ Although Les Promenades de Paris can be identified as the most influential work among municipal technicians, ⁴⁸ this case study shows that, despite their familiarity with the literature, the unique circumstances of the time—particularly the dismantling of the city’s first public garden—shaped their decisions. Faced with the challenge of determining the fate of more than 800 existing trees, the committee’s primary concern appears to have been how to preserve and replant as many as possible without jeopardizing the guiding principles.

In addition, other relevant publications from that era provide essential insights into the aesthetical, technical, and scientific requirements of boulevards’ planting. Although this literature is not in the library and some volumes were published after the committee’s decision, I consider they are still important to understand what nineteenth-century experts thought about the topic, namely regarding the best tree species for boulevards and the reasons for their choices. These include Manuel d’arboriculture des ingénieurs—plantations d’alignement, forestières et d’ornement (1860) by Alphonse Du Breuil; William Robinson’s The Parks, Promenades and Gardens of Paris (1869); Guide de l’ingénieur pour l’établissement et l’entretien des plantations d’alignement sur les voies publiques (1885) by Jules Nanot; Traité des plantations d’alignement et d’ornement (1896) by Adolphe Chargueraud; and Plantations d’alignement, promenades, parcs et jardins publics (1897) by Georges Lefebvre.

The selection of trees for street plantings is one of the most demanding aspects, as only certain species are suitable for this purpose. First, as the aim is to beautify the city, the trees must have an elegant appearance. In addition, since they are typically placed parallel along building facades, the trees should emphasize verticality, and at times, they should not exceed a certain height so as not to obscure the architecture. However, these trees are expected to provide more than just aesthetic value; they should also offer shade, making the shape and density of their canopies important factors.

Moreover, these trees must be highly resilient, as the urban environment is especially harsh below ground. Above ground, the trees are also exposed to diseases, pollution, and even acts of vandalism. Finally, the choice of species depends on the climatic and biophysical conditions of the planting site. Thus, the selection of trees for roadside planting should take into account the soil’s characteristics, the available sunlight, altitude, terrain configuration, and growth rate (with fast-growing trees preferred to more quickly achieve the desired effect). Trees that provide ample shade, have attractive foliage, and can reach substantial sizes without their branches drooping to obstruct pedestrian walkways are also prioritized.

Nineteenth-century theory which enhanced one sole tree species for tree-lined streets has been taken into consideration by the committee appointed by the City Council to decide on the choice of tree species for the Avenida da Liberdade in 1882. However, the dismantling of the Passeio Público rendered 822 trees—belonging to forty-one different species and varieties—disposable (see Appendix A). Several episodes at the Lisbon City Council demonstrate a growing sensitivity to the issue of tree felling. For example, the 1855 complaint by the councilor to the president of the Lisbon City Council about an act of vandalism against forty-six trees that were found cut down, which could only be attributed to the “brutal wickedness of the spirit of destruction.” ⁴⁹ Moreover, another complaint focused on sixteen trees cut down from Alegria square. ⁵⁰ Another episode involving tree removal revealed a dispute between two municipal departments, which escalated into a courtroom battle and received media coverage in 1884. ⁵¹ Both cases illustrate the emerging public concern for tree protection.

Planting such a wide variety of species was impractical for a boulevard. Thus, influenced by the recommendations of the literature of the time—despite some already pointing out the potential visual monotony—the search for unit by selecting one sole tree species was highly endorsed. Thus, one of the essential questions for the committee to resolve was whether to prioritize uniformity or diversity in the species used for the boulevard’s alignment plantings. With the avenue intersected transversely by five streets, there were twelve rectangular sections. According to the Technical Department’s plan, these sections required 1,208 trees arranged in eight rows, each containing 151 trees. The committee members, aware of the cost, time, and effort required to cultivate a tree to a mature state, were reluctant to recommend such destruction of the viable and reusable trees from the Passeio Público. Yet, they faced a dilemma: should they follow the design principles of international public gardens or adapt to Lisbon’s specific circumstances, which included a distinct heritage, aesthetic preference, and climate? A compromise solution was found. The approach combined unity with variety to make the best use of existing specimens. The commission proposed adopting a uniform species within each pair of sections. Since the Avenida da Liberdade was divided into twelve sections, twelve different species would be selected. This solution ensured unity within each section while introducing variety across the boulevard. By avoiding monotony, it allowed for the replant of a significant number of trees from the Passeio Público. This also meant that some areas were already planted with mature trees of substantial size.

This decision allowed the committee to select twelve species from the forty-one available in the Passeio Público, which corresponded to 523 specimens out of 822. This meant that 300 trees could not be replanted. However, it was the best possible outcome to save the life of as many trees as possible. However, things got worse when an accurate examination of each specimen excluded them from the boulevard’s design due to poor development, deformities, or diseases that compromised their viability. In total, 300 trees from the Passeio Público were deemed suitable for replant in the boulevard. As a result, the Lisbon City Council had to obtain the 908 missing trees from its own nurseries, municipal and national nurseries, or purchase them from commercial suppliers.

Tree transplantations were among the most complex and resource-intensive operations undertaken by the Department, requiring specialized equipment such as transplanting carts. In June 1873, the Lisbon City Council purchased its first tree-transplanting machine for 1,000$000 réis (historic Portuguese currency). Councilor Margiochi emphasized the need for such a device to allow the “easy removal of mature trees”—a tool, he noted, already common in places where tree life was respected and afforestation valued—highlighting how novel the equipment was in Lisbon. However, the French-made cart proved too large for many of the city’s streets, complicating an already delicate process. In 1882, likely in response to the dismantling of the Passeio Público and the need to relocate its trees, Councilor Viscount of Carriche requested two additional carts from Paris, priced at 4,350 and 4,700 francs, respectively, both shipped from Le Havre. ⁵²

The transformation of the Passeio Público and the subsequent planting of Avenida da Liberdade encapsulate a pivotal moment in Lisbon’s urban and environmental history (Figures 4 to 6). It was not only a technical and aesthetic endeavor but also a cultural one, shaped by local constraints, global ideas, and the commitment of an unusually interdisciplinary group of experts. Faced with conflicting priorities between innovation and conservation, unity and diversity, theory and practice, the committee’s solution represents an early and notable example of adaptive urban greening. The deliberations surrounding species selection, the logistical complexities of transplantation, and the preservation of valuable trees all attest to an early and evolving awareness of environmental principles, anticipating what would later be formalized as ecological thinking.

Figure 4.

“Passeio Publico,” in Archivo Pittoresco, no. 42, 1863, p. 329.

Figure 5.

The Avenue of Liberty, view from Vale do Pereiro, by Ribeiro Cristino, in O Occidente, no. 235, July 1, 1885.

Figure 6.

View of Avenida da Liberdade. Lithograph by João Christino, in the supplement to “Mala da Europa” (“The Suitcase of Europe”) No. 488, 1905.

The Selected Trees

The selection of trees for the Avenida da Liberdade was an exercise that was supposed to be done without constraints in order to choose what would be the best for the novel Haussmannian-like boulevard. But that was not the case. Not only the circumstances of the Lisbon boulevard were shaped from the outset by the historical context of the dismantling of the Passeio Público, as the outcome is totally different from the Parisian boulevard, which acted as a role model for all Europe.

The committee ultimately listed twelve tree species it considered most suitable for planting along the avenue, and the number of specimens that existed at the Passeio Público of each of them (see Appendices B and C).

According to Alphonse Du Breuil (1811-1890), a French horticulturist and prolific author of specialized works on arboriculture, fruit tree cultivation, viticulture, street trees, vegetable gardens, and ornamental gardening, the best tree species for ornamental plantings in urban contexts are sycamore maple, plane tree, horse chestnut, wych elm, silver poplar, Canadian poplar, western plane tree, Dutch lime tree, silver lime, and tree of heaven. ⁵³ According to Alphand, the only species that met all the criteria trees had to comply for tree-lined streets were the plane tree and chestnut tree, though he also considered elms, limes, acacias, poplars, tulip trees, zelkovas, catalpas, and paulownias. ⁵⁴ The Irish gardener and journalist William Robinson (1838-1935), who has written about the Parisian parks and boulevards, considers the Platanus occidentalis the best tree for European cities. After the plane, the horse chestnut is also highlighted for its great merits as a city tree. Although it lacks the stature and health of the plane, it compensates with its fine foliage, silvery blooms, and resilience in urban settings, even in hard and constrained soil. Then, he points out the robinia or locust tree as another excellent urban tree choice, having proven its resilience over time. Its adaptability makes it ideal for parks, squares, and even streets, as it does not grow too large. It is particularly recommended for planting in front of suburban homes or villas, where it serves as a refreshing sight year-round. ⁵⁵

However, most French specialists listed a wider range of options. Jules Nanot, a nineteenth-century horticulture and forestry expert from the French National Agronomic Institute, deemed that the most suitable species for roadside plantings included tree of heaven, catalpas, cedars, sycamores, ashes, chestnuts, walnuts, elms, paulownias, poplars, cherries, plane trees, acacias, limes, and tulip trees. ⁵⁶ In his opinion, oaks and beeches, although they could be chosen, they should be a second choice as they do not meet ideal roadside planting criteria. For this purpose, it is recommended that trees should have trunks about 16 to 20 cm in diameter, with at least 1 m of trunk before the canopy, and a total height of 4 to 6 m. Oaks and beeches, by contrast, have trunks around 8 to 10 cm in circumference and stand 2 to 3 m tall, making other options more viable. ⁵⁷

Only 40 percent of the committee’s suggestions aligned with those found in French literature, which identified the following as ideal for alignment plantings: tree of heaven, catalpas, cedars, oaks, sycamores, ashes, beeches, chestnuts, walnuts, elms, paulownias, poplars, hornbeams, planes, acacias, lindens, and tulip trees (see Appendix D). The only species selected by the committee that matched the French recommendations were Ailanthus glandulosa, Platanus orientalis, Ulmus campestris, Fraxinus excelsior, and Robinia pseudoacacia. Some of these species were already common in Lisbon. Between 1858 and 1879, a greater number of mulberries, acacias, Judas trees, and elms were planted throughout the city. ⁵⁸ However, while the selection of species complies with specialized French literature, it does not align with the primary French model as implemented on the Champs-Élysées—originally exclusively planted with elms and later replaced by horse chestnuts.

Therefore, as we have seen, neither French literature nor French practice was strictly followed in Lisbon. While the Champs-Élysées initially featured two rows of elms—later replaced by chestnut trees—Lisbon’s proposal, though aligned with the popularity of elms, embraced a greater variety of species. This diversity clearly distinguishes the Lisbon solution from its Parisian counterpart.

Above all, they were taking into consideration the legacy from the Passeio Público, although the primary objective was to select beautiful trees that would not only enhance the city’s aesthetic appeal but also provide ample shade, allowing citizens to comfortably stroll along the boulevard even on the hot, sunny days typical of Mediterranean climates like Lisbon’s. In nineteenth-century Lisbon, there was already a growing awareness of the role trees could play in improving atmospheric conditions and urban climate, contributing to environmental quality in urban spaces. In 1868, the idea to establish Lisbon’s lungs in Monsanto was launched by the physician Carlos Ribeiro and the Royal geologist Nery Delgado as “this would give the city a brighter appearance and likely modify the climate, effectively contributing to public health.” ⁵⁹ In 1878, Teófilo Ferreira, the city councilor responsible for municipal works, requested the appointment of a committee to study which places and streets should be planted with trees, and “which plant species were best suited to the climatic conditions of the capital, as well as to the geological circumstances of the terrain,” expressing the desire that the commission be assisted by “some practitioners and theorists in arboriculture.” ⁶⁰

Moreover, the choice of resilient trees had to prevail as tree roots not only encountered urban debris but also a new challenge from nineteenth-century urbanization, namely gas-fueled street lighting. All the trees proposed by the committee are resilient to urban context, and the majority are large-sized trees. The large majority are exotic trees as only tree are native species—Celtis australis, Populus alba, and Ulmus campestris.

The analysis of nineteenth-century specialized literature highlights the different conceptions, nomenclature, and even misunderstandings toward a tree species. Take the example of an exotic species, which is currently considered invasive in Portugal: Ailanthus glandulosa (now accepted as Ailanthus altissima), commonly known as the tree of heaven. It was also referred to “by the French vernis du Japon,” ⁶¹ as Robinson stated. This is currently called faux vernis du Japon as it is not the same tree as Toxicodendron vernicifluum.

The tree, originally from China and Japan, is a deciduous tree with spreading foliage and oblong, elliptically shaped, with green leaves and small, greenish-yellow flowers in summer followed by reddish-brown fruit. This was deemed excellent for ornamental planting along major public streets. Du Breuil considers it one of the top ten species of tall trees for ornamental plantings among the ones he suggested for alignment plantings in general. ⁶² Robinson considers it is a town tree of great excellence and states that “the qualities that will above all others recommend it to the town planter are its perfect health and freshness, under all circumstances, in towns.” However, he does “not recommend its use on an extensive scale”; despite existing “many positions in London in which it would be highly appropriate.” ⁶³ Nanot, who describes it in detail and analyzes its cultivation in France from its acclimatization in the King’s Garden in 1751 to its adaptation to the gardens and streets of Paris, offers the following advice:

The flowers of the male plants emit a very unpleasant odor during blooming, though fortunately, it does not last long. Some individuals concerned with the comfort of pedestrians have recommended planting only female plants on the boulevards. However, before following this advice, it would be prudent, in our view, to verify whether the female plants are as vigorous as the male ones. ⁶⁴

Nanot also acknowledges that the Ailanthus is a tree that establishes itself very easily and grows at an extraordinary rate, allowing an avenue to be formed quickly. However, the trees, often of uneven vigor, ultimately result in irregular rows. He concludes by stating that for ornamental plantings along major public streets within cities, where it is frequently encountered, it is a valuable tree due to the beauty of its shape, its foliage, which provides ample shade, and its resistance to insect damage. It is also prized for its easy establishment, rapid growth, hardiness, and, above all, its low requirements regarding soil type. The few criticisms that can be made are that it releases an odor during blooming that bothers pedestrians, that its foliage develops somewhat late, that it produces suckers that are harmful to nearby crops, and finally, that it sometimes forms irregular rows. Although Chargueraud does not add information to what Nanot mentions, he includes two interesting illustrations of the tree, one of them in winter, almost as an advice about the poor effect it offers during that season (Figures 7 and 8). ⁶⁵

Figure 7.

Ailanthus glandulosa in Chargueraud, 1897, 193.

Figure 8.

Ailanthus glandulosa during winter in Chargueraud, 1897, 193.

The Robinia pseudoacacia, or black locust, is a medium-sized deciduous tree native to parts of the United States but widely planted and naturalized in temperate regions worldwide, where it is sometimes considered invasive as in Portugal. Nevertheless, there were eighty-seven specimens at the Passeio Público. Black locust trees grow 12 to 30 m tall with a diameter of 0.6 to 1.2 m, featuring a straight trunk, narrow crown, reddish-black deeply furrowed bark, and zigzag branches that change color as they mature. It was brought around the year 1601 to the Jardin des Plantes in Paris. ⁶⁶ In 1869, they had already some accumulated experience on its usage in urban spaces to such an extent that Robinson stated that they had “no more doubt about it.” ⁶⁷ It was very resistant to drought as “few other trees stood the heat of the summer of 1868 so well, and after the drought was ended it looked as if it had just passed through a showery month of June.” ⁶⁸ Nanot stresses it has an easy recovery and an exceedingly rapid growth, it is unaffected by “smoke,” and rarely attacked by insects. ⁶⁹ However, despite its decorative flowers, Nanot alerts to the fact that the rows of plantings it forms are generally not uniform, as it is rare for all specimens to grow at the same rate. For ornamental plantings on public thoroughfares and promenades, this constitutes a problem. Furthermore, it does not provide sufficient shade. Nevertheless, Nanot concludes that its low demand for soil quality and its rapid growth make it valuable. ⁷⁰ Despite being criticized for more than one author due to its insufficient shade, Robinia pseudoacacia was recommended for Avenida da Liberdade. ⁷¹

Another large-sized tree extant at the Passeio Público was the Platanus orientalis, of which there were twenty-two specimens. This tree is also known as the Oriental plane. It is a large deciduous tree that can grow up to 30 m tall, with a spreading crown and remarkable longevity. Its leaves turn blood red, amber, and yellow in autumn. Native to riverine areas of Persia, northern India, and Asia Minor, it was introduced to France around the mid-eighteenth century. The Greeks and Romans loved this tree so much that, according to legend, the people watered it with wine instead of water to boost its strength and growth rate. The tree features deeply lobed, maple-like leaves, often with flaking bark, and produces round, burr-like flowers in clusters. Some specimens are over 100 m in total volume and hundreds of years old. This differs from Platanus occidentalis primarily in its native region, leaf shape, and climate adaptability, with P. orientalis being more suited to Mediterranean climates, while P. occidentalis thrives in temperate, riverine environments and has broader, less lobed leaves. Both species are known for their flaking bark, but P. orientalis tends to have a more patchy appearance. The tree’s canopy is typically more elongated than that of the Western Plane. Its leaves usually have five long lobes separated by deep sinus cuts, which is why it is referred to as the “Hand of the Ancients.”

Unlike the Western Plane, the Oriental Plane does not require such fresh soil and should ideally be planted in the southern regions where the soil tends to lack moisture. Propagation can also be done through root cutting. The less hardy Oriental Plane had almost entirely disappeared in the nineteenth century. However, some distinguished nursery owners have a different opinion, stating that in the boulevards of Paris, about half of the planes were Oriental. ⁷²

The committee has also selected the tree of which there were more specimens and that was one of the most recommended taking into consideration both theory and practice: elms, of which there were 146 at the Passeio Público. Ulmus campestris, also called Ulmus minor, or the field elm, is a highly polymorphic European species, with its natural range extending from southern Europe to Asia Minor and Iran, and its northern limits in the Baltic islands. It thrives in low-lying forests along rivers, tolerating both summer floods and droughts. The species is characterized by a variety of forms across Europe, including small-leaved, narrow-leaved, and densely hairy varieties. British varieties of field elm are most closely related to those of central Europe. While taxonomic classification has been debated, Richens’ 1983 breakdown into regional varieties is commonly accepted, though some later research suggests multiple distinct species and hybrids.

The Ulmus campestris, native to Europe and inland Siberia, was strongly recommended for roadside and especially boulevard planting. ⁷³ Following Nanot,

elms, which have many qualities for alignment plantations, are unfortunately very susceptible to insect damage, especially during dry years and when planted in light, shallow soil. A few years ago, in Paris, due to this issue, elm plantings were significantly reduced, and there was even a time when it seemed they would no longer be planted, as the wood and leaves were completely destroyed. Nowadays, the problem is much less intense. ⁷⁴

In his opinion, this is a tree recommended for economical plantations along roads and for ornamental plantations on boulevards, and so on. The tree is decorative, with dense foliage, strong and high-quality wood; its establishment and growth are excellent. It thrives in all exposures, does not require very deep soil, and, lastly, tolerates pruning and takes on any shape. It would be a wonderful species if insects did not show a harmful preference for it, especially when planted in inner areas. ⁷⁵

At the Passeio Público, there were also fifty-three European ashes. Fraxinus excelsior is a large deciduous tree native to Europe, extending to the Caucasus and Alborz mountains, and is cultivated in regions like New Zealand and North America. It can grow up to 43 m tall with a narrow crown and smooth pale-gray bark that becomes fissured with age. The leaves are pinnately compound, with seven to thirteen coarsely serrated leaflets, and are often the last to open in spring and the first to fall in autumn. The flowers are wind-pollinated, and the tree can be either male or female, sometimes changing sex. The fruit is a samara, commonly known as “ash keys,” which germinates only after two winters if fully ripe. European ash trees typically live up to 250 years, with a few exceeding that age.

Nanot considered the tree is often affected by insects, notably cantharides, which produce an unpleasant odor. Therefore, it is not recommended for planting near promenades or homes. ⁷⁶ The tree is easy to transplant and grows quickly, but it is often noted that individuals from the same line do not grow with the same vigor, leading to irregular planting. This tree is particularly suited to coastal areas and places with strong winds, as it is deeply rooted, and its very resilient branches form a narrow crown that faces the wind with little resistance. Light, sufficiently moist soils are the most suitable; its roots extend to the surface and do not require deep soil. It does poorly in compact and waterlogged lands. The ash tree grows well in the shade of other trees, but if it exceeds a certain height, the water draining from its leaves becomes harmful. ⁷⁷

In Lisbon, some tree species not recommended in literature also gained prominence, such as Morus alba (white mulberry), originally from China and India. The white mulberry (Morus alba) is a fast-growing, small to medium-sized deciduous tree native to China and India, and reaching heights of 10 to 20 m. Although it was widely cultivated and naturalized in warm temperate regions, and it thrives in various soil types, including poor soils, it is not addressed in literature dedicated to tree plantings in urban contexts. However, its culture has long been naturalized in Portugal by the Marquis of Pombal in order to feed silkworms as he aimed at increasing silk production. In the 1858 survey of trees planted in Lisbon, 953 out of 2,791 specimens were mulberries. ⁷⁸ Therefore, past political and economic decisions rooted in the country’s history underlie the choice of this tree species.

The following two tree species are not among the most recommended in specialized literature, but in both cases, around 70 specimens were to be taken from the public garden, and this may have influenced their inclusion in this selection.

Populus alba, commonly known as silver poplar, is a deciduous tree native to regions from the Atlas Mountains in Africa to Central Asia, thriving in moist, and temperate areas. It typically grows 15 to 30 m tall, with smooth, greenish-white bark that darkens with age. The tree has five-lobed leaves covered with white down, thicker on the underside, and produces dioecious catkins (male and female on separate trees). The female catkins grow into green seed capsules, maturing in late spring to early summer. Populus alba also propagates through root suckers, forming clonal colonies. It is not commonly recommended for urban settings in nineteenth-century literature. However, Nanot recommended poplars such as Populus monilifera, Populus pyramidalis, and Populus angulata, but not Populus alba, which was designated for planting on Avenida da Liberdade. ⁷⁹

Celtis australis, also known as the European nettle tree, Mediterranean hackberry, or lote tree, is a deciduous tree native to Southern Europe, North Africa, and Asia Minor. It can grow up to 25 m tall, though it is typically smaller in cooler climates. The tree has smooth, gray bark and narrow, sharp-toothed leaves that are dark green in summer, turning yellow in autumn. It produces small, green, wind-pollinated flowers and edible dark-purple berries, which are popular with birds and wildlife. Robinson indicates this as adequate for tree-lined streets based on the Parisian boulevards that connect the Bois de Vincennes with the promenades in the neighborhood. ⁸⁰

Of the following two tree species, there were no specimens to replant from the Passeio Público and they were neither prominently recommended in specialized literature nor supported by any known historical justification. Therefore, it is even more difficult to speculate what were the criteria behind their inclusion in this selection. The honey locust (Gleditsia triacanthos), a deciduous tree in the Fabaceae family, native to central North America and widely cultivated, is not addressed in literature dedicated to tree plantings in urban contexts. It can reach heights of 20 to 30 m and is known for its fast growth and medium lifespan of up to 125 years. The tree features pinnately or bipinnately compound leaves that turn yellow in autumn. It blooms in late spring with strongly scented greenish-yellow flowers in clusters. The fruit is a flat, twisted pod containing up to twenty dark seeds surrounded by sweet pulp. In my opinion, it was its distinctive light green foliage, pleasant fragrance, and strong adaptability to Lisbon’s climate and biophysical conditions—despite its absence from the surveys conducted in 1858 and 1879—that might have motivated the choice.

Another selected tree of which there were no specimens to replant from the Passeio Público was Sophora japonica (Japanese pagoda tree), now classified as Styphnolobium japonicum. It is a deciduous tree in the Fabaceae family and has pinnate leaves with nine to twenty-one leaflets and pendulous raceme flowers similar to those of the black locust. It has medicinal properties, with its floral buds used in the pharmaceutical industry. In Portugal, Styphnolobium japonicum is an introduced species and is currently considered invasive as it competes with native plants for space and nutrients. In the nineteenth century, there was no such knowledge. Robinson considered it “one of the many deciduous trees of which the wintry aspect is preferable to that presented by smutty and halfdead ‘evergreens.’” ⁸¹ We can only speculate that the criterion behind this choice was the unusual aspect of the tree with the branches and leaves hanging down toward the ground.

Since some of the twelve recommended species were not used in the boulevard’s sections, the committee proposed utilizing these species in each of the squares. Given that both squares would have monuments at their centers—the Monument to the Restoration and the Monument to the Marquis of Pombal—the committee emphasized that the chosen species should have small canopies to avoid obstructing the visual impact of the monuments when viewed from a distance. Therefore, for these squares, they recommended Broussonetia papyrifera and Cercis siliquastrum, two not that tall trees but very colorful with yellow and pink leaves. Both species are not recommended by nineteenth-century literature. ⁸²

The paper mulberry (Broussonetia papyrifera), also known as the tapa cloth tree, is a deciduous shrub or tree in the Moraceae family, native to Asia, including China, Japan, and Southeast Asia. Widely introduced to regions like Europe, the United States, and Africa, it typically grows 10 to 20 m tall. Its leaves vary in shape, with toothed edges, pale undersides, and a rough texture, measuring 15 to 20 cm long. Its fruits are small, red, or orange drupes forming spherical clusters. Cercis siliquastrum, commonly known as the Judas tree, is a small deciduous tree native to Southern Europe and Western Asia. It grows up to 12 m tall and 10 m wide. The tree is known for its striking deep pink flowers, which appear in spring on older growth.

Besides these trees, the committee proposed sparing two magnificent Ficus rubiginosa and six Araucaria excelsa found in the Passeio Público as these were deemed botanically important and valuable and could not be relocated without causing significant damage (Figure 9). As we can see, the choice of trees is not always guided by the species we find in the greatest quantities, but also by the opposite criterion—rarity and exotic appeal, which have proven to be influential factors in the selection and preservation of tree species. ⁸³ Individuality stem from both the characteristics and from the trees’ position, and the committee considered them high-quality botanical specimens but was also aware that they would not survive transplantation. Therefore, sacrificing them for the sake of species or variety uniformity within a section was considered barbaric. Moreover, these elements could serve as focal points for creating small landscaped areas featuring ornamental foliage plants, adding a picturesque touch to the new avenue. These minor interruptions in the alignments, in the committee’s view, would humanize and soften the space. ⁸⁴ As we have seen, the committee’s choice was driven for different criteria.

Figure 9.

Lisbon’s Entrudo in 1911: Another Aspect of Carnival on the Avenue, Illustração Portugueza, série 2, vol. 11, no. 264 (March 13, 1911), 347.

Final Remarks

Although the committee’s decisions were framed in the language of scientific knowledge, aesthetic refinement, and horticultural awareness, the guiding force behind their actions was, above all, practical necessity. The dismantling of the Passeio Público presented an immediate logistical and ethical challenge: what to do with over 800 trees that would otherwise be lost. This urgency placed circumstantial and pragmatic concerns above strictly botanical or ecological ideals.

Indeed, while the selection of species appears thoughtful and informed by contemporary literature—including principles such as visual harmony, seasonal synchronization, and resilience to urban stress—the primary constraint remained the reuse of displaced specimens. As a result, many of the final choices reflect adaptation rather than innovation: an effort to reconcile what was theoretically desirable with what was physically available and logistically feasible.

This pragmatic approach does not imply ignorance of horticultural science. On the contrary, the committee demonstrated a clear familiarity with prevailing botanical theories and urban design trends, particularly those disseminated in French planning models. Their awareness of concerns like species uniformity, aesthetic monotony, and seasonal coordination suggests an intellectually engaged response to a complex urban challenge. However, the actual implementation often deviated from these ideals in favor of more immediate and localized needs.

Ultimately, the species selection for Lisbon’s boulevard reflects a hybrid logic: one part grounded in the realities of urban transformation and municipal budgetary limits and another part shaped by a culturally and climatically sensitive reading of contemporary planting practices. The result is not merely a transplanted model of European urbanism but a distinctly local reinterpretation—an exercise in ecological compromise and spatial creativity that responds to Lisbon’s unique historical and environmental context.