Introduction

Like other spaces¹ for the acquisition of knowledge, such as the laboratory, botanical gardens are not just tools² to help generate botanical knowledge, they in fact constitute botany as such.³ The first gardens were created in the early modern period at European universities: in Pisa and Padua between 1543 and 1545, followed by Bologna, Florence, Rome (1563) and Leiden (1587) etc.⁴ In addition to close ties with universities, which still prevail today, other institutions also acted as sponsors of botanical gardens. Thus, in 1673, the "Society of Apothecaries" established the "Chelsea Physic Garden" in London, which maintained connections with other botanical gardens and, as a result, was committed to regularly supplying new herbarium records to the most important English research institution, the "Royal Society".⁵ Academies began setting up gardens, such as the "Royal Prussian Society of Sciences" in Berlin, initiated by Gottfried Wilhelm Leibniz (1646–1716) in 1711, which was entrusted with the former show garden of the Prussian king in 1718.⁶ In the 18th century, the economic interest in exotic plants and the competition between European powers led to expeditions and the establishment of characteristic botanical gardens within large palace complexes at courts in Paris, London, Vienna,⁷ and Hanover. In the same century, the botanical garden of Leiden in the Netherlands and the Parisian "Jardin de Plantes" were initially considered to be the most exotic collections of living plants, but were then surpassed by Vienna (in the 1780s) and later by Kew Gardens near London. In the 19th century, the educated bourgeoisie discovered this space of knowledge for themselves for entertainment and aesthetic edification purposes. They organized their own botanical gardens within the framework of horticultural societies and local museum associations. Today, gardens are still run by municipalities, for example in Augsburg and Linz. With the nationalization of science, botanical gardens were also established as national institutions, often together with natural history museums. In the United States, the first President George Washington (1732–1799) designed the space for the "United States Botanic Garden" near the House of Congress as an integral part of the new capital. The garden was formally established by the "Columbian Institute for the Promotion of Arts and Sciences" in 1820.⁸ To this day, new botanical gardens are being created worldwide as a result of government initiatives. China has followed suit by establishing more than 100 gardens since 1956, whereas one garden was created in Palestine (Jerusalem) in 1931 and one in Oman in 1989.⁹

Regardless of the sponsor, the botanical garden is of European origin. As a result of European colonialism and furthermore acting as its instrument, the first gardens emerged overseas from the mid-18th  century onwards (e.g. in Calcutta in 1787). In the British Empire, the Kew Gardens was an essential focal point for the colonial gardens in West and East India from the mid-19th century. It continues to serve as a model even today and is probably the most important scientifically managed garden in the world.¹⁰

Understood as a knowledge space, the botanical garden unites dichotomous categories of knowledge, such as practical and theoretical, implicit (tacit knowledge) and explicit, abstract and concrete (real), local and global, uncertain and certain, mediated and secret, grand and mundane knowledge.¹¹ It almost goes without saying that practical, horticultural, and implicit knowledge (manual work), for example, are prerequisites for the care of any garden. The very existence of the botanical garden is permanently dependent on gardening work. Failure to do this work can have fatal consequences for the plant population. If plants are cultivated from foreign climatic zones, however, practical knowledge about them must first be acquired through experiments. A new form of architecture developed in the 19th century due to the construction of greenhouses which were necessary for acclimatization – often initially called "Warm- und Kalthäuser" (warm and cold houses) in German. Characteristic monumental buildings made of iron and glass, such as the new railway stations or the "Crystal Palace" of the botanist and architect Joseph Paxton (ca. 1803–1865) in London (1851) produced a new technical design for dome greenhouses, plant rotundas, greenhouses, and palm houses.

Scientific significance from a spatial and praxeological perspective

In the botanical garden, plants which are naturally separate from each other are brought together in one place – literally forming "the world in miniature". Direct comparison is only possible by means of an overview or consolidation. In 1671, the Medical Faculty of the University of Freiburg (Methodus docendi medicinam in Facultate medica Universitatis Friburgensis Brisgoiorum) accordingly set out the garden's essential function in this regard:

... however, since it is very difficult to find various kinds of herbs and plants, which grow in different places, a garden was once allocated to the Faculty of Medicine in order to plant there what was necessary for this purpose....¹²

The advantage of having plants coexisting lies in the possibility of making direct comparisons. In general, the classification of species is based on a specific perception of nature which is affected by cultural change. During the 17th century the traditional concept of the doctrine of signatures, which was based on the assumption that features hidden in the interior had externally visible effects, became obsolete. How did this change, doubtlessly central to the establishment of botany, come about?

According to the well-known explanation of their origin, the first botanical gardens, known as hortus medicus, were used to showcase medicinal plants.¹³ The humanists' characteristic written knowledge culture, however, was transformed in the gardens into a visual form of knowledge dissemination, which was tied to the spatial dimension. Other centers of knowledge such as cabinets of curiosities, libraries, anatomical theaters, and laboratories emerged at the same time as botanical gardens. In these spaces, objects could also been seen as carriers of knowledge. For example, the term theatrum became familiar as a designation for books. It contained a reference to the visible and thus referred to the acquisition of knowledge through sight. This form of knowledge acquisition was embedded in a social courtly culture, which is one of the main reasons it was able to manifest itself.¹⁴

In the 16th century, these knowledge spaces gained in importance, especially in the wake of the printing press. Knowledge located in space became permanent.¹⁵ For this reason, mnemonics, already established in antiquity, gained renewed interest in the 16th century. According to rhetoric, memory, as the most important element of knowledge, was topologically encoded.¹⁶ The urge to acquire knowledge through collection expressed itself in new knowledge spaces. Memories could be "preserved" in books and in libraries. The "theater of memory" projected to the outside what was once attributed to the interior, but which changed through the new spatial practice of appropriating things. Scientific findings and cultural interpretations affected the space. Botany could only understand itself as a descriptive science by concentrating on the external characteristics of plants. The new knowledge spaces allowed the elites to integrate the healing knowledge monopolized by the monasteries as part of the courtly culture. Therefore, it is no coincidence that the monastery garden may be considered a precursor to the botanical garden.

The visibility postulate went hand in hand with the classification and comparison of individual plants.¹⁷ As a result of the European expansion, driven by curiosity and the desire for exotic plants, the transfer of unknown plants into the gardens became a common field of activity for botanists. In order to preserve the experiences scattered over time and space during a herbation, excursion, journey, or expedition, images and descriptions were produced along with the transfer of live plants, seeds, and dried specimens.¹⁸ Bruno Latour (born 1947) called them immutable mobiles¹⁹ because all document forms could be further processed. While illustrations, descriptions, and the herbarium technique²⁰ were already available in the 16th  century, they began being professionally produced in the 18th century, mainly through the standardization of Carl von Linné's (1707–1778) description method.²¹ The botanical garden was the place where representations and plants collided and were bundled together.

An unprecedented institutional continuity imparted the botanical garden with significance. Privately run gardens, which also existed, had the disadvantage that they were usually bound to a person's lifetime. To be considered a botanical garden, a number of qualitative criteria had to be met, including the existence of a library, a collection of dried plants (herbarium), and the meticulous recording of cultivated plants and seeds.²² All types of gardens are weeded and harvested, but in the botanical garden all cultivated plants are managed and registered in inventories. These catalogues²³ were, on the one hand, a means to control the garden and to cultivate many plants; but on the other, they served the communicative exchange with other gardens, whereby the inventory could be extended. To give a sense of the scale: In mid-19th century Wroclaw, 6,000 to 8,000 seed samples and 500 to 600 pieces of living plants were shipped annually. The garden received 2,000 to 3,000 seed samples and 200 to 300 new plant species for its own inventory.²⁴ This seed documentation can still be found today in many of the gardens' library collections. It shows those gardens with which the site was or still is in exchange. Through these relationships, each botanical garden became an important interchange of its European network.

Herbarium records, illustrations, and descriptions circulated from botanist to botanist, from one botanical garden to another. The periphery, for its part, constantly enriched these gardens with still unfamiliar plant material and biodiversity. Returning to Bruno Latour's concept: In contrast to the descriptions or illustrations, the transferred seeds or living specimens in the gardens were not immutable mobiles – their sizes were not unchanged. The living plant in the garden had a notable disadvantage compared to representational forms: Its appearance changed depending on the season and local conditions of cultivation, which makes unambiguous classification more difficult. These changing conditions, however, expanded the stock of varietals, which greatly stimulated the discussion about the species. While species identification and taxonomy served as justification for the gardens for a long time, from the 19th century onwards botanists were fascinated with questions about the cause of hybridization and changes among different climatic conditions. The garden had become a testing laboratory where it was possible to observe a plant's changes under variable living conditions rather than its existence in its natural habitat.

Economy and domination: Imperial and global knowledge spaces

Botany has always been influenced by economic and feudal aspects – although this was hardly discussed by botanists themselves and older historiography. As early as the 16th century, the first gardens did not concentrate on medicinal plants for doctors in training, but on expanding the plant inventory according to territorial references. For example, the botanical garden in Padua – which was under control of Venice as part of the University of Padua – benefitted from the Venetian Republic's trade links stretching as far as the eastern Mediterranean. Only in the first century of its existence, plants were introduced to the Padua garden from Egypt and the Black Sea area (the Ottoman Empire).²⁵ In Leiden, probably the most important colonial botanical site of the 17th century, the expansion of the plant inventory accompanied the activity of the overseas trading companies.²⁶ From the 16th century and over the course of several decades, a botanist's work profile that was oriented towards the entire global space emerged. At the latest since Carl von Linné, traveling, collecting, and botanizing overseas were no longer merely incidental activities of travelers dedicated to missionary work, trade, or diplomacy, but turned into independent fields of activity. At the same time, the botanists involved in expeditions and the gardens were part of new global interests aimed at the economic distribution of bio–resources: Tropical crops such as the clove tree (Syzygium aromaticum (L.), Merill et L. M. Perry) or the nutmeg tree (Myristica fragrans Houtt.) illustrate the history of crop transfer and the related role of botanical gardens as points of transfer. Until 1770, these two spice plants grew exclusively on the Moluccas. The monopoly, which was stringently guarded by the Dutch, was penetrated by the French transfer via the Isle de France ("Garten Pamplemousses," today "Sir Seewoosagur Ramgoolanin Botanical Garden on Mauritius") to the West Indies (the French Antilles).²⁷ In 1802, the British succeeded in acquiring several thousand nutmeg plants in the Moluccas and brought them to the newly established botanical garden of St. George on Penang Island. From there, the plants were brought to the overseas English possessions within only a few decades. As president of the Royal Society Joseph Banks (1743–1820), a fellow traveler of the first Cook expedition, turned the Kew Botanical Gardens near London into a center for the economically important transfer of plants.²⁸ At the end of the 19th century, there were already 102 colonial gardens of the British Empire (they accounted for 38 percent of all gardens worldwide),²⁹ which also affected the cultivation of plants in the colonial areas. The director of the Royal Botanic Garden in Peradeniya (1821) in Ceylon (Sri Lanka) had the run–down coffee plantations cultivated with plants that promised higher yields. Between 1873 and 1876, an inconceivable number of more than three million seedlings of Cinchonia pubescens (cinchona bark) was delivered to local growers, massively interfering with the island's ecological and economic system.

Botanical gardens preserved and managed the knowledge of the species with the help of herbaria and living specimens. But they were more than just spatial "evidence centers"; they served as centers of exchange and, in a sense, as "shunting stations" for seeds in the worldwide transfer of crops. Accordingly, they were regarded as botanical centers of calculation of imperialism. Moreover, in Kew – as we have known since Brockway's study³⁰ – botanical expertise served to attain profit and power and thus supported an industrial-economical world system of empire. The activities of Kew Gardens, for example, have enabled the tea plant to be successfully transferred from China via Kew to Darjeeling. Following London's example, the Berlin Botanical Garden at Dahlem was also established as a hub in the network of German protectorates. From around 1890, the "Botanical Central Office for the German Colonies" in Berlin equipped its subsidiary facilities in Amani (East Africa), Victoria (Cameroon), the experimental gardens at Misahöhe and the Socodé (Togo) and in Simpson Harbour (New Guinea) with plants and staff trained in Berlin. All shipments of plants to and from the German colonies were supervised from the Berlin Garden, which functioned as a link between science and colonial economic interests.

For a long time, the transfers focused on unknown plants. In contrast to this, during 21st century, those immigrants (neophytes) have gained increasing interest that emerge undetected as a result of globalization and have come to dominate or even proven to be invasive with respect to native floras. Likewise, the garden has recently been assigned a role which is increasingly similar to a Noah's Ark. It not only implements and demonstrates plant protection itself, but also follows the development of endangered species and, at the same time, ensures public acceptance of new protective measures through different media channels.

The manifestation of theoretical concepts in botanical gardens

The theory of the order of the plant kingdom is not only created, but also shown in the arrangement of a botanical garden. Accordingly, nature is designed in different forms, following the systematic concept of plants. In early gardens circles with one large and several small rectangles inscribed dominated. This form corresponded with the doctrine of the elements,³¹ which represented a complex system in which the macrocosm referred to the microcosm. The combination of circle and rectangle as it was realized in Padua³² had a symbolic and knowledge–constitutive meaning: According to Plato, the circle referred to the perfection of the cosmos. At the same time, the design was also anchored in architectural and practical proportion theory, which followed geometric-mathematical relations and presented harmony. Quadrinity pointed to the cosmos, which, in contrast to chaos, was shown as ordered. Simple geometric shapes (either rectangles or squares) prevailed in the botanical garden until the 18th century.³³

Initially, the plants were processed alphabetically or according to their medical efficacy. Herman Boerhaave (1668–1738) was the first garden director to insert the cultivated species in the Leiden garden according to their family affiliation in rows, i.e. in relation to a plant systematics.³⁴ During the 18th century, Linné's system prevailed over competing classification methods and thus determined the design of the botanical garden. Geometrically coherent rows were arranged in the garden complex. The guided perceptions in the garden were based on a rigid classification system in which each plant was clearly assigned its place, in the book as in the actual garden. This unambiguity corresponded to the idea of an unchangeable nature (constancy of the species), which only changed in the 19th century, when the knowledge on the species increased.³⁵

Both the rows in the garden and the book illustrations suggested an overview, similar to apodemics (instructions for traveling) that propagated the view from above, e.g. from the city towers to the topography of the city or from the peaks of the mountains, which were "conquered" by natural scientists from the end of the 18th century.³⁶ Through this cultivation technique a detailed register was created, an inventory of enumerables, of fragments, and of plants in rows. Synthesis, on the other hand, only became possible when the plants were assigned to actual geographical–ecological units and thus to a collective, to a plant community. This concept was propagated in particular by Alexander von Humboldt (1769–1859), to name the most important representative of plant geography. It was taken up aesthetically for the first time in the design of the English Garden in Munich in the 19th century. Geometric shapes were replaced by curved lines and transformed, as in Jena and Berlin.³⁷ Here, the gardens had previously been schematically divided into rectangular surfaces and areas similar to landscape parks. During the course of the industrialization and the densification of cities, these gardens became the green lungs of the urban space.

The renunciation of geometric arrangements, however, required a spatial expansion. Many botanical gardens had to be relocated from center of cities to their peripheries in the search for more space. In Berlin, where the university – newly founded in 1810 – took over the garden managed by the academy, the relocation of the botanical garden from Schöneberg to Dahlem took place around the turn of the 19th century (1897–1910). The plant geographer Adolf Engler (1844–1930) conceptualized groups referring to Europe, Asia, and North America in their transcontinental span. The garden made plant geography the basis of the plant arrangement in an unprecedented spatial extension. The brainchild of Anton Kerner of Marilaun (1831–1898)³⁸ was the first attempt to present the vegetation of the Tyrolean Alps en miniature in the Innsbruck garden in 1860. Adolf Engler transferred this idea to the temperate zones of the entire northern hemisphere and created the "alpinum".³⁹ Anton Kerner introduced this garden section, popular today in many gardens as a separate cluster, to the Innsbruck Botanical Garden and transformed it into the center of internationally renowned Alpine studies. However, from now on the showcase and the experimental space started to fall apart. In the Innsbrucker garden, the mountain ranges of Tyrol were clearly depicted in the rock garden, and long-standing series of tests were set up at various experimental sites and different heights to document the cultivation of alpine plants as a consequence of environmental and non–heritable changes. This resulted in debates on the controversial hypothesis regarding the inheritance of acquired traits.⁴⁰

Like museums, botanical gardens presented their objects outside their respective environments and instead placed them in knowledge–based contexts that had been redefined from the 19th century. These included geographical and functional groupings (woody plants, succulents, aquatic plants, etc.) according to their technical use and to habitat–related contexts. During the mid–19th century, the most species–rich gardens in the world (St. Petersburg, Kew in London, and Berlin) had no less than 25,000 plant species. By this time, the botanical garden was thrown into crisis, which resulted in debates surrounding its reform. Anton Kerner, who worked in Innsbruck and at the botanical garden in Vienna, pleaded for a representative selection instead of a misguided accumulation of species.⁴¹ According to Kerner, the garden had to meet the challenges of new botanical disciplines such as physiology and morphology. Following the classical garden model, most botanical gardens in Europe still concentrated on taxonomy.⁴² In contrast to this, Kerner suggested that gardens should provide the living material for morphological and physiological demonstrations and investigations and thus serve as a kind of resource pool. Instead of providing plant material for use in the laboratory, Kerner considered the garden itself a laboratory, a field of experimentation. Some gardens had already served this purpose from the 17th century when botanists specifically identified the acclimatization of plants as a priority topic of investigation. This line of research was extended in the 19th century to include location issues of the plants.

As with anything that can benefit from the typically huge spatial dimensions in the USA, botanical gardens which were created there became frontrunners. The "Huntington Botanical Gardens" founded in 1904 were established in San Marino (Los Angeles County) by creating a park consisting of 15 different gardens, including a desert garden, a Japanese garden, and a palm garden.⁴³ In the 20th century, botanical gardens were faced with the challenge of explaining the concept of evolution by showcasing different stages of plant development. In Freiburg, the evolution of the system of flowering plants was presented by showing individual groups of plants marked in circles with connecting paths between these units which represented the lines of development.⁴⁴

Dissemination and appropriation

University teaching regulations from 1609 show the extent to which their education was based on visibility:

Moreover, since most of the medical teaching only reveals itself when recognized through visual inspection and scrutiny with the eyes, the lowest professor [tertiarius] of this college takes the students out into the open when the weather is favorable and assembles them to get to know the various species of plants [...] where he offers them [the students] the possibility of observing and evaluating for themselves.⁴⁵

Learning to look and to concentrate on individual traits resulted in the acquisition of theoretical–abstract knowledge in a vivid way. Non-verbal knowledge (form and recognition of the plant) was related to verbal knowledge (naming). For a long time, memorization was the main element of education. In this respect, the garden as a space of structured knowledge in its ordered totality offered an advantage over the open terrain in its bewildering diversity, since each learning unit could take place repeatedly and in a focused manner. Labels with numbers usually affixed to the plants, which corresponded to the names published in the garden catalogues, acted as memory triggers.⁴⁶ Soon, however, these were replaced by name plates made of sheet metal or wood. To this day, they remain part of the natural inventory of botanical gardens, referring to names and thus belonging to the eminently important practice of recording and recognizing plants.

As late as 1824, the Berlin botanist Heinrich F. Link (1767–1851) favored the garden as a place of learning over the open country in the chapter on methodology of his work Elementa Philosophiae Botanicae⁴⁷, even dismissing student excursions as useless. In the botanical garden, it was possible to acquire knowledge of plant names, plant parts, and their systematic arrangement under optimal conditions. According to Link, the botanical garden was the best learning source, superior to others because it stood out amongst the range of various non–verbal media characteristic for classical botany.

In the botanical garden, the arrangement of plants guides the viewer's perception. Over the course of the 19th century, when natural sciences increasingly gained interpretative authority among the public, the botanical garden gradually assumed the role of a public educational institution. Specifically, scientifically secured knowledge was made accessible to laypersons, primarily the educated middle classes. Like all other sites of knowledge transfer, the garden was now equipped with display boards on which individual plant species or phenomena were presented in a compact form. And yet, the new audience not only wanted to be instructed, but also sought edification, enjoyment, and entertainment. With its exoticism in the new glass and tropical houses, especially the large palm houses, the botanical garden was perfectly suited to meeting this demand. In addition, it also served as a venue, presenting a world dominated by imperialist Europe.

The garden made it possible for visitors to observe the life cycle of a plant, from seed to flower. Within the context of this cycle, a unique flower often represented a special event – and was presented as such by the gardens from the 19th  century. With attractions such as the titan arum from Sumatra (the largest flower in the world from the standpoint of flower biology) gardens continue to hold the public's fascination.

Marianne Klemun