Padua Botanical Garden: One of the Oldest 
Orti Botanici’ in the World, is also a Hub for Botany and Science in the 21st Century.

The Botanical Garden in Padua — Historic Notes

The Botanical garden in Padua (Orto Botanico di Padova), with its more than 450 years of history, represents the most ancient University institution of its kind to have maintained the original layout insisting over the same location, mostly unaltered, from its foundation until today — and so is the structure. 

The date of foundation is usually considered to be 1545 — the day in which the Consiglio of the Serenissima Repubblica of Venice, by accepting the proposal of Francesco Bonafede, then appointed chair of the Lectura Simplicium, deliberated — with an almost unanimous vote — the institution in Padua of a physic garden (Horto Medicinale) where to grow, observe and experiment both with the autochthonous as well as the exotic (for the time, at least) medicinal plants.

The need for an institution of this type appears clear, if one considers that plants represented, at the time, the basic ingredients for the majority of medicines, and that the use of plants for therapeutic purposes was almost exclusively based on the texts of ancient authors. The interpretation of these texts, however — also because of the various transcriptions — was rather controversial, and there were frequent errors of identification of the species being described. This often implied the use, in medicine, of the wrong plants, either devoid of therapeutic value, or — much worse — even toxic for our organism. 

The possibility of having the availability of a Horto, where students in medicine — as well as becoming well-versed with the theory — could receive a practical training, and would gain experience, allowed also for the individuation of the frequent sophistication and frauds to whom were subjected at the time the vegetal simples, by the suppliers and the ‘speziali’ (the specialists involved in the preparation of the drugs) alike.

Created as Horto Medicinale, the garden has followed over time the evolution of the botanical studies, by adapting its collections to the changed didactic and scientific needs of the time.

Amongst the various Prefects that have succeeded one another in the direction of the Botanical garden in Padua, can be counted scientific personalities of prominent position in various sectors of the botanical disciplines, such as the famous doctor Prospero Alpino, the florist Roberto de Visiani, the mycologist Pier Andrea Saccardo, and the physiologist Giuseppe Gola.

Structure and Organization

The project of the Horto Medicinale (also known as Horto dei Semplici) is generally attributed to a Venetian scholar, the patrizio Daniele Barbaro, who also became Patriarch of Aquileia, and Pietro da Noale, then eminent Professor of Medicine at the Padua University. To the realization of the project almost certainly contributed also Andrea Moroni, from Bergamo, whose name is connected to numerous other architectural realizations in the city of Padua, amongst which is the Palazzo del Bo’ (headquarters of the University), the Basilica of S. Giustina and the palazzo that currently hosts the Town Hall.

The Horto is found on an area of trapezoid shape of about 2 ha on a terrain which was once property of the Benedictine Monks of S. Giustina; it is delimited on two sides by the Canale Alicorno, from which — until a few decades ago — water for irrigation was being taken. The original nucleus of the Orto Botanico is represented by the so-called Hortus Sphaericus, of about 85 m in diameter, in which a square is inscribed, which in turn is divided into four smaller squares known as ‘quarti’, separated by two perpendicular avenues, and oriented according to the cardinal points. The circular shape and the characteristic geometric subdivision, which divides the area into 16 partitions, is rich in references and cosmic symbology, typical of the Renaissance period. Currently, each quarter is endowed with a central fountain, and subdivided into 250 plots, disposed according to different and elegant geometries. 

The external architectonic configuration was completed at the beginning of the 1700s with the realization of four monumental entrances, the gates in ironwork of refined make, and the balustrade in pietra d’Istria that towers above the circular wall. To the same century also belong the statue of Theophrastus, situated by the southern entrance, and those of Solomon and the Four Seasons, located by the homonymous fountain. The glasshouses and the Botanical theatre have also been realized in the first half of the 1800s; currently, there are two hot houses and 8 temperate glasshouses of modest dimension, one of which still maintains the original structure, with small columns and cast-iron arcs. 

The Main Collection

As a consequence of the limited availability of glasshouses, the living collections of the Orto Botanico are located mainly outside. The number of cultivated plants is currently of about 6,000 specimens (taxa), and their collocation follows mainly taxonomic, utilitarian, historic and ecologic-environmental criteria.

The systematic collection is concentrated in the four major central beds. The first quarter is dedicated to monocots, while the following quarter hosts the dicots: it displays a predominance of perennial herbaceous plants, of certain rusticity (hardiness), representative of both the Italian flora as well as — in a lesser way — the exotic.

Among the collections of utilitarian value, particularly meaningful is the collection of medicinal plants; it is subdivided into two sectors, one of which is reserved to plants of current interest — that is, of pharmaceutical and herbal use —, while in the second find their home the ‘Semplici’, which have had a certain applicative interest in the past and now only have a historic value. Each plant is tagged with a label that reports — besides the scientific name — also the main therapeutic applications.

Recently, a collection of poisonous plants was also set up, with specifically didactic purposes: some belong to the autochthonous flora of Veneto (Colchicum, Veratrum, Aconitum, etc.), while others represent species of common ornamental usage (Lily of the Valley, Oleander, Thuja sp., etc). On the label is also reported an indication of their degree of toxicity, as many of these plants can also be found within the sector of the medicinal plants, as — if used in adequate doses — they can carry out a healthy role in the cure of illnesses. 

The carnivorous — or rather insectivorousplants constitute one of the most renowned and admired collections within the Orto Botanico. With a total of about 30 species, manly of exotic origin, this collection offers a rather complete documentation of the main morphological adaptations, and in particular of the apparatuses and systems used to capture insects, which can be either active (as for instance in Dionaea) or passive (such as in Drosera, Sarracenia, Nepenthes, etc.). 

The aquatic plants are hosted, in their majority, in the two great pools located near the northern entrance to the Hortus Sphaericus (Round garden). The thermal characteristics of the water, with a constant temperature of about 25° C, allow the cultivation in the open also of exotic species, normally quite difficult to acclimate in the Po valley. Amongst the species present here appear also examples of plants anchored to the soil (Papyrus, Lotus, Waterlilies, etc.), as well as floating plants (Water Hyacinth, Pistia sp., Water Lentil, etc.). Since a few years, is also being cultivated in the open air — and with optimum results — the renowned, giant waterlily from Tropical America, Santa Cruz Lily (Victoria cruziana).

Two of the temperate glasshouses of the garden host, during the winter months, a valuable collection of succulent plants, exposed with a systematic criterion; during the summer months, this same collection is split apart, and showcased outdoors. The most represented families are the Cactaceae (in particular the genus Opuntia), then also the Agavaceae, Aloaceae, Crassulaceae and Euphorbiaceae.

The orchid collection (Orchidaceae) is constituted of about 150 botanical entities, and around 50 hybrids or horticultural varieties. Within the same glasshouse, is also present an interesting collection of ferns, whose representatives range from aquatic species to land species and epiphytes, thus displaying various examples of localization of the spore tissues (within the leaf).

The plants of the Colli Euganei, and other rare plants of the Triveneto, are two sectors of recent realization: they also respond to one of the fundamental roles of botanical gardens, which is to make known to the public the most characteristic plants of the territory where they are situated, and thus collect, conserve and study the plants which are in danger of being lost, also with the goal to insure the preservation of biodiversity. 

In the Orto botanico have also been recreated some natural environments that propose examples of vegetation typical of the Mediterranean maquis, of Alpine rock habitats, peat-bogs and of the Venetian littoral. 

Among the multi-centenary trees present in the garden, particular significance is given to a specimen of Dwarf Palm, also known in Italian as “Palm of St. Peters” (Chamaerops humilis), planted in 1585 and and better known as Goethe’s Palm, since the great German poet, after having studied it in 1786, expressed his intuitions on the evolution of the species in the essay The Metamorphosis of Plants.

The Oriental plane (Platanus orientalis), with the characteristic cavity that came to be created in its trunk precisely because of a lighting strike, constitutes another historic relic for the Orto, together with a majestic specimen of Ginkgo (Ginkgo biloba), as well as a Magnolia (Magnolia grandiflora), both dating to first half of the 1700s, and considered among the oldest living specimens of these species in Europe. 

In the Arboretum is also being displayed, laying on the ground, the sub-fossil trunk of an oak (Quercus robur), lived around 700 BC, which testifies to the forests that were once covering the whole of the Po valley plains.

Individual Notable Trees Within the Garden

The “Black Pine of Calabria” (Corsican Pine)

The meaning of the genus Pinus is connected to sap, a resinous substance present in conifers. The Black Pine of Calabria (also known in Italian as “Black Pine of the Sila” — a mountainous range in the heart of Calabria, as this tree is characteristic of the woodlands of this region) is present also in Sicily and Corsica (and for this reason, it is often known as Corsican Pine in English); it actually constitutes a sub-species of the more common Austrian Black Pine; for this reason, it is scientifically classified as Pinus laricio subsp. laricio Maire. 

This is an imposing conifer, which in nature can reach and surpass 40 m of height. The trunk, straight and slender, presents a bark which is subdivided into large sub-rectangular plaques, grayish-white, with marginal furrows of a blackish color, from which it takes the common name of Black Pine, which also recalls the black color of the tip of the scales, in the cones. The pyramidal canopy, when young, takes a typical dome-shaped aspect in mature individuals. The leaves are needle-shaped as in most conifers, with needles about 10-15 cm long, flexible, not very sharp, and grouped in small bundles of 2 (in fact, the majority of specimens has needles grouped by 2, but there are a few cases in which groups of 3 or 5 needles have been observed). The masculine inflorescences (called micro-sporophyll) are short and gathered in cylindrical catkins, also clustered in small bundles. The female inflorescences (cones) are conic- or ovoid-shaped, becoming elongated when ripe (about 6 cm long), which then open and free their seeds, endowed with a wing which is useful in order to favor seed dispersion. The ripening of the strobilus happens within a two-year cycle; for this reason, one can observe the 1-year old cones, the 2-year old ones, and those which have already dispersed their seeds (which will usually fall during springtime of the third year) on the same plant. The Corsican Black Pine grows preferably on acidic soils, while the more common Austrian Black Pine is more typical of calcareous soils. 

The “Black Pine of Calabria”, situated in the vicinity of the entrance to the ‘Orto Botanico’ — as it can be inferred from a plan by Francesco Saccardo (1887) —, appears to have been planted in 1836. Currently, it reaches a height of about 20 meters, and displays an expanded, dome-shaped crown, typical of an adult individual. 

In the ‘Orto Botanico’ are present — besides this specimen — three other Black Pines, one of which, located in the arboretum in the proximity of the sub-fossile oak trunk, seems to have been planted circa 1760, and could perhaps represent a surviving specimen from the “bosco vecchio” (the so-called ‘old wood’), created by Prefect Giovanni Marsili in 1760. 

Black Pines have been hit, over the last few years, by a fungal parasite (Diplodia), which is causing serious damage to the survival of the species. Also, the specimens present in the ‘Orto Botanico’ have been infected by the disease, but they are constantly being monitored for their conservation. This individual, and the other Black Pines present in the garden, for their meaningful historical value and their exceptional monumental standing, are contemplated among the great trees of the city (see also the list “Grandi Alberi Monumentali della Provincia di Padova”). 

Goethe’s Palm

This is a specimen of Dwarf Palm (even though the individual displayed here looks all but small!), also known as St. Peter’s Palm (Chamaerops humilis L.) — a name given by Linnaeus in order to distinguish it from its taller, fruit bearing counterpart, the Date Palm (Phoenix dactylifera L.). Despite its botanical name, the plant that can be observed in the Botanical Garden reaches with its main trunks the height of about 11 meters. Currently, it represents the oldest living plant (‘decana’) of the Orto Botanico, being the oldest living organism within the garden, dating from the same year as its foundation (the date in which the Palm has been planted is the same as the foundation of the garden, 1545). Its notoriety, however, is not so much due to the fact that it is the oldest plant here; rather, as it was immortalized by a famous man: no less than the celebrated poet and naturalist Johann Wolfgang Goethe (1827-1832). The German poet visited the Botanical Garden in Padua on Sept. 27, 1786, and this is how the illustrious visitor described the place and his impressions: 

“The passage of the Alps awoke in me vividly that inclination that I already felt for Nature in general, and for plants in particular. The larches more frequent than at lower levels; the cones of the domestic Pine still new to me, made me more aware of the effects of climate on vegetation. Despite the rapidity of the journey, I remarked other plants more or less modified by this (aspect), but as I entered the Orto Botanico in Padova, I was bedazzled by the magical outlook of a Bignonia radicans, which covered with its red trumpets a long and tall wall, which seemed on fire. I understood then all the richness of the exotic vegetation. Many small trees, which I had seen vegetating miserably in our stoves (= glasshouses), were growing here in the open air of the countryside. The plants that a light shelter had protected against the passing colds of a not-so-harsh winter, enjoyed in the open ground the free benefit of the air and sun. A Fan Palm (Chamaerops humilis) then attracted all my attention. The first few leaves that rose from the ground were simple, and sword-shaped; then they went on dividing up more and more, until they appeared parted as the fingers of an open hand. A small branch, laden with flowers, was rising in the middle of a sheath, shaped like an arrow, and it seemed like a most singular and unusual creation, utterly estranged to the transient vegetation that surrounded it. The gardener, giving in to my pleas, therefore cut me some representatives of the series of these transformations; and I, in turn, overloaded myself with a great many cartons, as to take away with me what I had found. I still keep them under my eyes as when I picked them up at the time, and I venerate them almost like fetishes, which by reawakening in me and fixing my attention on to them, made me glimpse the happy results which I could await from my works”. 

Even though this theory, published by the author under the title of “Essay on the Metamorphosis of Plants” (of the leaves, in this specific instance), had no scientific validation, it represented, however, an important boost for the Orto Botanico in Padua, towards national and — above all — international visitors.

HabitatChamaerops humilis is the only truly spontaneous palm in Italy. It lives along the western costs of the Italian peninsula, in Sardinia, Siclly and in the smaller islands. It prefers high cliffs with low herbaceous vegetation and open, arid clearings near the sea, displaying a noteworthy ability to adapt to our climatic conditions, resisting also winter temperatures of up to -5° C. It presents a variable height, depending to the environment in which it thrives, ranging from a few dozen cm on the coastal cliffs to 4-5 m in the best conditions of growth. The specimen here in Padua clearly befalls into this second category, and it has reached an astonishing height thanks to the protected setting which has been created for it.

The ‘Orto Botanico’ and the Carraresi Herbarium

At the time of the Carraresi (the family who ran the city of Padua at the time of the foundation of the garden), many doctors and University professors studied the cultivation of plant and animal products in the service of health. Among these was Jacopo Dondi, who wrote Aggregator medicamentorium sue de medicinis semplicibus, a treaty on the natural substances used in medicine. Francesco Novello da Carrara was also very interested in medicine and natural sciences: this is demonstrated by the inventory of his library, compiled by Francesco Zago in 1404, which includes 61 codes on these themes; Zago himself was a functionary of the Carraresi court.

The Herbarium of the Carraresi (“Erbario carrarese”) — now held at the British Library — is another extraordinary document on medicinal plants: this is a version in vulgar of the original Liber aggregtus in medicinis semplicibus, written by the 12th century Arab doctor Serapione (Serapio) the Young. It was copied by the Eremite brother Jacopo Filippo da Padova, and it alternates pages of text with extraordinary miniatures depicting the plants in all the details necessary to understand their use. The method of the Carraresi Herbarium was based on gathering knowledge by the direct experience and observation of nature. This anticipated the application of empirical principles in natural sciences, and is related (connected) to the founding, in 1545, of the Horto Medicinale (Medicinal — or Physic — Garden), annexed to the University of Padua. The garden was originally intended to serve in science and education, and concerned itself with indigenous and exotic medicinal plants, but the collection increased as botanical science developed. The influence exercised by the Botanical garden was enormous; its variety and vastness were such to include many roles, and it served as an inspiring example to foreign scholars, thus offering and encouraging the international exchange of plant material, as well as the knowledge associated with it. Today, in addition to the species of medicinal and poisonous interest, the Botanical garden includes sectors dedicated to the local flora, to rare and threatened plants, and to species of tropical, Mediterranean, Alpine and peat-bog (acidic) environments. 

Other Herbaria and Museum Collections 

Besides the living collections within the Orto botanico, in the building to the side of the Casa del Prefetto (Prefect’s House) are present many other collections, connected to the Centro di Ateneo (main University hub) for all of Padua University Museums, which altogether represent one of the most important botanical, scientific and historic documentations in Italy. They are constituted by the so-called Erbario Fanerogamico (Phanerogamic Herbarium) and Erbario Crittogamico (Cryptogamic Herbarium); a Xiloteca (collection of wood specimens) and a Spermoteca (Bank of plant sperm); a Cecidoteca and a Chermoteca. The Erbario Fanerogamico, composed of more than 400,000 dried specimens (exiccata), includes the Erbario Generale, the Erbario Veneto, the Erbario R. de Visiani della flora Dalmatica (a Herbarium specifically dedicated to the flora of Dalmatia), the Erbario Fenologico A. Marcello (Phenologic Herbarium) and a general Herbarium for consultation, used for didactic purposes.

Activities and Projects

In the same way as other Botanical gardens in Italy, also the Orto Botanico in Padua — during its more than four centuries of life — has contributed to the introduction and diffusion in Italy of numerous exotic plants, some of which have become very well-known and of daily use in our times — such as potato, sunflower, Lilac, rhubarb, cyclamen —, for a total of about 70 species. A specific collection, situated in front of the glasshouses, documents these introductions, which are being exposed in chronological order. Since a few years, has been set up  for the first time in Italy  also a didactic itinerary specifically devised for visually impaired people. Exhibited here, are thematic collections of plants cultivated in pots that can be substituted during the year; each plant is endowed with particular characteristics, which can be appreciated by touching or smelling it, and it is labeled with an aluminium or terracotta tag, which indicates the name and peculiarity of the given species in Braille.

The Orto also has a Visitor Centre which, besides providing a wide documentation on the history, architecture and collections of this UNESCO site, also offers the possibility to make use of audio guides and multimedia guides, useful for a self-guided visit of the garden, as well as a shop connected to the University.

In 1997, the Orto Botanico in Padua has been included — as “cultural asset” — in the List of the World Heritage Sites of the UNESCO. This list includes all those cultural or natural goods (or assets) to which, because of their outstanding quality, is recognized a “universal exceptional value”, and which therefore represent invaluable and irreplaceable assets, not just for the nation where they are located, but also for the whole of humanity. They deserve therefore a particular protection, with the goal to ensure their conservation and transmission to future generations. The Botanical garden in Padua has been inserted in the UNESCO World Heritage List in consideration of the fact that it testifies to an exchange of considerable influences within the cultural area of botany, and thus represents a unique — or at least exceptional — example of a multi-secular cultural tradition, as it is clearly stated in the motivation: “The Orto Botanico in Padua is at the origin of all botanic gardens in the world, and represents the cradle of science, of scientific exchanges, and of the comprehension of relations between nature and culture. It has largely contributed to the progress of numerous modern scientific disciplines, and most notably in the fields of botany, medicine, chemistry, ecology and pharmacy”. In 2008, the Orto Botanico in Padua has also been included in the 3rd “Rapporto EURISPES” on the excellences of Italy, and counted among the hundred most representative cases of Italian successes within the national system.

The Bank of Germplasm

The annual collection of seeds at the Orto botanico, and their cataloguing in an Index Seminum (list of seeds), finalized to the exchange with other similar institutions, dates back to 1823. Since 1978, the offer of seeds has been also integrated with that of germplasm, collected in nature.

To the traditional conservation system has been flanked, since 1992, the conservation system of preserving seeds in the cold (cryopreservation).

The spaces reserved to the exsiccation, processing and conservation of the seeds — as well as the biological tests — have for a long time been constituted by two rooms for an overall area of 50 sq. m; with the widening of the Orto botanico in an adjacent area, much wider spaces and more suitable equipment have been dedicated to this goal; this has contributed to the creation of a bank of germplasm.

Short-term conservation, which allows to maintain the vitality of the seeds for 5-10 years, is reserved to the seeds of species collected in the Orto, and those collected in nature that are not classified as rare and/or threatened entities for the local flora; these seeds are being conserved in paper bags, in a dedicated closet, in an air-tight space. The species conserved in this way are being listed in the seed catalogue (Index Seminum), which is being compiled every two years, and that is subsequently sent to other 800 botanical institutions around the world.

Long-term conservation, in relation to the lack of air-tight spaces that were once available, and the specific equipment, for a long time has being reserved to seeds of rare and threatened species of Veneto and Friuli, collected according to a predetermined plan (with much more space available since the extension of the garden, these conservation efforts have now widely expanded). This second system envisages the freezing of seeds at -18 °C, and allows to ensure their vitality for a period superior to 10 years.

The species conserved in cryopreservation are currently 83, some of which have been included also in the Habitat Directive (amongst them, Erucastrum palustre, Gypsophila papillosa, Saxifraga berica); others are in the National or Regional Red List, as complied by I.U.C.N. and/or S.B.I. (for example, Euphrasia marchesettii, Haplophyllum patavinum, Moltkia suffrutticosa); others still have local relevance, as for instance the threatened species of the Colli Euganei (such as Crypsis schoenoides, Thymelaea passerina).

With the goal to facilitate the finding of local wild entities to be conserved ex-situ, a pact of mutual collaboration has recently been agreed upon with the Giardino Botanico delle Alpi Orientali di Monte Faverghera (Belluno) and the Giardino Botanico Alpino del Cansiglio “G. Lorenzoni” (Tambre dAlpago).

Since 2005, the Orto has subscribed to the association R.I.B.E.S. (“Rete Italiana Banche del Germoplasma”), for the conservation ex-situ of the wild Italian flora.

The Biodiversity Garden

After more than 450 years of life, the Botanical garden needed a deep renewal in order to combine together tradition and openness to the future. The Biodiversity Garden greenhouses are a great showcase; an ideal cross-section of the globe which slopes away from the Equator to the poles. From the most favorable living conditions with abundant humidity and high temperatures where rainforests can grow, to the most extreme conditions where the cold and scarce water make life almost impossible. The project has retained the empty space in the urban fabric represented by the existing Benedictine vegetable gardens before the change made at the beginning of the 1950s, while the relationship with the former vegetable gardens is more than just a simple re-proposal of their forms; it rather derives from re-interpretation of the compositional rules governing the layout of the 16th C part. The Renaissance architecture used shapes such as the circle and the square, together with numerical modules. An idea transposed into design of the extension, respecting the dimensions and proportions present in the schemes regulating the old Hortus cinctus, and maintaining the same orientation of the axes which cross the great circle and visually connect the domes of the monumental complex of Santa Giustina to those of the Sant’Antonio basilica. An urban place, therefore; an integral part of the city’s fabric, within which a visit can take multiple forms, with display areas and spaces for entertainment and interaction.

The Biodiversity Garden Numbers About 1,300 Plant Species 

Plants are all around us: they have changed the Earth’s atmosphere so that we can breathe. For 450 million years, they have been the pillars of the Earth’s ecosystems, the most beautiful features of our landscapes: astronauts have admired them from space; animals have evolved alongside them. Over the centuries, we humans first gathered them, and then artificially selected them: our food, our medicines, our cosmetics, clothes and objects of daily use depend on them. We think that we have domesticated them, when in fact, it is they which have domesticated us. The food and the materials of the future will also rely on these amazing living organisms. More than 350,000 plant species are known, but the existence of many of these is at risk. These special organisms are the protagonists of our journey around the Garden of Biodiversity.

The plant species present in the Biodiversity Garden exhibition project number about 1,300. They live in environments sharing the same humidity and temperature characteristics, simulating the climatic conditions of the planet’s biomes, from tropical to sub-humid, temperate and arid zones. The position of the plants in each environment and in the aquatic plant lake reflects a phytogeographic division.

The section “Plant and Environment” is a voyage through the Earth’s vegetation (in America, Africa and Madagascar, Asia, temperate Europe and Oceania), and the visitor can immediately see a representation of the richness (or poverty) of the biodiversity present in each climate zone. The Biodiversity Garden does not represent the planet from the viewpoint of man or the animal world; the attention is shifted rather onto the various forms of plant life. Starting with the question: “What is a plant?” and “what characteristics make them so indispensable for our existence?”, the role played by plants in human evolution emerges, from the earliest settlements in prehistoric times until today.

As early as 1880, in the text The Power of Movement in Plants, Darwin wrote that “the tip of the radicle acts like the brain of one of the lower animals”: an intuition backed by the most recent scientific discoveries, and which is the ideal inspiration for the section “Plant and Man”. Information panels, films, interactive displays and exhibits recount how the intelligence of plants and the intelligence of humans have co-evolved in parallel from Lucy until our times. Plants tell of their age-old relationship with man — used to nourish, treat or construct the objects which make up our history. Outside the greenhouses, the flowerbeds are dedicated to specific themes, with the cultivation of species compatible with the local climate, such as food plants, flower gardens, and aromatic herbs. The themed gardens in fact represent a space open to realization in the name of the Garden’s scientific interest and dissemination to the public. 

Solar Active Building

This Building Has Been Designed to Reduce Environmental Impact to a Minimum.

This building has been designed to reduce environmental impact to a minimum — a 100 m long, 18 m high showcase in which the shape, layout of the spaces and installations have been optimized to exploit to the full the natural energy available free from the sun. The building plays an active role in transforming both the inside and outside environment, thanks to design and technological features which reduce the environmental impact. Natural precipitation feeds a 450 m3 collecting pool; the same body of water, which marks the entrance to the Biodiversity Garden, also ensures the constant mixing and oxygenation of the water reservoir. From a depth of 284 m, an artesian well takes up water at a constant 24° C, allowing tropical aquatic plants to live all year round. This water also integrates the water reservoir in periods of drought. The electricity produced by photovoltaic panels powers the pumps regulating the water cycle, and contributes to the operation of the entire greenhouse system. The opaque internal and external surfaces are covered with a photovoltaic compound which exploits ultraviolet rays to produce a chemical reaction: this considerably reduces atmospheric pollution — estimates speak of 150 m3/m2 cleaned of pollutants each day. 

A new technique for growing shrubs has been used on the non-transparent roofs of the structures. Transforming these areas into places where plants can grow has positive effects on the environment, from reducing the building’s energy consumption to producing oxygen and reducing carbon dioxide and particulate. The greenhouse effect is exploited to save energy and at the same time keep the environment within the temperature and humidity parameters specific to each climate zone. The heat produced by the sun’s rays remains imprisoned in the greenhouses; in winter, the masonry parts accumulate the heat and release it during the night. During the summer, instead, the heat is mitigated by opening the glass walls and roofs of the greenhouses —  and the signal to open or close the windows comes from the plants themselves, as they react to the environmental conditions by releasing carbon dioxide and oxygen in different degrees, as the humidity and temperature vary. A computerized system relates the data provided by the plants to the optimum parameters for life in each of the climate zones. The greenhouse roofs are made from cushions of ethylene tetrafluoroethylene (EFTE), a corrosion resistant plastic, lighter than glass and more transparent to the UV rays vital for the plants. The roofs are shaped to accumulate the sun’s heat, creating a buffer of air which reduces dispersion by radiation during the night. To obtain the visual effect of a 100-m-long perfectly flat piece of glass, a new system has been devised to fix the panes, free from external profiles or through elements, but able to support wind loads of more than 400 kg/m2. 

“Plants and the Environment” 

A Wood. The Sea. A Beach. Even City Parks and Gardens ... all are Ecosystems.

Each centimeter of our planet can be an ecosystem, or more simply, part of one. For example, the temperate forest which covers areas as far apart as much of Europe, Asia and North America is an ecosystem. But individual ecosystems are not separated by rigid boundaries, and at different times organisms can ‘transit’ from one ecosystem to another. The fluidity of nature leads us to simpler forms of identification: this is where terrestrial biomes come in. Almost as in a snapshot, they unite ‘near’ ecosystems, characterized by the same environmental conditions, although perhaps very far apart in purely geographical terms: the new greenhouse thus takes the visitor on an imaginary journey from the Equator to the Poles. Here follows the description of some of the main ecosystems.

Tropical Rain Forest

The Tropical rain forest extends from the Tropic of Cancer to the Tropic of Capricorn. With an enrage T of about 25° C, and oscillations of 2-4° during the year, rainfall is so abundant that in most of the areas it reaches 2,500 mm/year. Tropical rainforests cover just 7% of the earth’s surface, but according to estimates, they contain more than 50% of the planet’s biodiversity. 

Sub-humid Tropical Forest and Savannah

Precipitation in the sub-humid climate zone and savannah is lower than in the rainforest, with values of just over 800 mm/year. The average temperature drops below 20°C, with oscillations of some ten or so degrees over the twelve-month period. The sub-humid climate is typical of the Indian subcontinent, South-east Asia and southern China, but also the African jungle (such as in the Gulf of Guinea or the Congo Basin), central America along the Atlantic coast and some areas of South America — such as Venezuela. The savannah is a plant formation present in some areas of eastern and central Africa too, as well as in Guyana and Australia.

Temperate and Mediterranean Climate

Temperate climates are characterized by cool winters, warm summers, and high year-round precipitation. Biodiversity is relatively high due to the niche partitioning allowed by the multiple forest layers. More complex forests are associated with a greater number of animal species. The Mediterranean is the least extensive of the temperate climates, and can be found in southern Italy, Sicily and Sardinia, and in the coastal areas of Spain and France. But similar climatic conditions occur along the coasts of Turkey and in the Near East, the Maghreb, the Cape region of South Africa, California, Chile and south-west Australia. Temperate climate zones cover less than 2% of the Earth’s surface; they are threatened by heavy pressure from man, but still contain 20% of the entire wealth of biodiversity.

Arid Climate

Arid climates are characterized by scarce precipitation (less than 250 mm/year), but there are hot arid climates and cool arid climates. The first are typical of North Africa, the Arabian peninsula, certain parts of North America, Chile and Australia. An example of the second is the entire zone stretching from the Caspian Sea to the Gobi Desert in Mongolia. 

“Plants and Man”

Source of sustenance and remedy to treat illness; means of alleviating fatigue and ‘simple’ material (to make objects, ornaments, musical instruments and writing implements), but also myth and religious symbol: these are plants in their daily relationship with man. The Biodiversity Garden tells their stories — and here are some of them:

Coffea arabica

The coffee plant was described for the first time in Italy by Prospero Alpini, physician and then prefect of the Botanical garden. In his De plantis Aegypti from 1592 — written after a long adventurous voyage to Africa — he talks of the therapeutic uses of the drink obtained from its toasted seeds: it is the prelude to the arrival of coffee in the West, brought by the Venetians during the 16th and 17th C. It immediately spread widely, and was cultivated everywhere climate permitted. The Dutch took the coffee to Java (1699) and Guyana (1714); it did not arrive in Brazil until 1727, but the country then became the world’s coffee greatest producer. 

Ravenala madagascarensis

Despite its name, the so-called Traveller’s Palm — national symbol of Madagascar — is in fact not a palm. Its name is linked to the travellers who drank the water accumulated by its imposing leaves. It was also used in traditional building — the leaves were used as a roof covering; the large large leaf stalks to make dividing walls in the local houses, and the bark used as a flooring material. It is also used for its fibre and as a food. A sugary substance is obtained from the lymph of its trunk, and its edible seeds contain a food oil, halfway between palm oil and cocoa butter; finally, the pith is used as animal feed. The species is also of great ornamental interest, thanks to its interesting shape, similar to a large open fan. 

Cycas circinalis

This plant originates in a limited area of southern India, in the Karnataka, Kerala and Tamil Nadu states. Gathering of Cycas leaves for floriculture and felling to extract the pith from the trunk (eaten by the local population) has led to deforestation, which has destroyed more then 50% of its original habitat in just over fifty years; as a result, in 2009 Cycas circinalis entered the International Union for the Conservation of Nature’s Red List as a species at risk. 

Theobroma cacao

Theobroma means “food of the Gods”, confirmation of the elitist connotation of its early use as a food. The properties of cocoa were certainly known more than 2000 years ago among the native populations of the tropical rain forests of central and south America, where the species grows in the wild. Some studies have shown the existence of cocoa residues in drinking containers found in Honduras and which can be dated 1150 BC. As shown by archaeological finds, chocolate consumption among the Mayas must have been reserved for the nobility and special occasions. It seems that the Aztecs, on the other hand, used it to prepare a bitter drink, consumed cold and considered aphrodisiac. It contained various ingredients such as maize and cocoa seeds, water, red chilli pepper, annatto (giving an orange color to the drink), and other spices, such as vanilla. Cocoa was considered so precious that until the 19th C its seeds were also used as money.

Mangifera indica

This large evergreen tree can grow to a height of up to 30-40 m, and its foliage can reach a circumference of 10 metres. It is one of about 50 species of the Mangifera genus, which grow in various parts of south east Asia. About half of these, including M. indica, have edible fruits which are widely used by the local populations. Mango is considered the national fruit of India, Pakistan and the Philippines, and — according to FAO figures — Mangifera indica is the sixth most important fruit species in the world, with production amounting to 26 million tons per year. But the ancient roots of its use by man also include numerous religious and symbolic meanings in the popular Indian culture.

Succulent plants

Even in arid environments, there are close links between the human and plant communities. The latter have developed a particular adaptation to the environment, characterized by scarce surface development with cylindrical or spherical forms and an absence of leaves. They absorb water rapidly when available, and give it up slowly as it is consumed for the plant’s metabolic processes. In parallel, over time, the human populations living in desert environments have learnt to use the scarce plant resources available to their best advantage. The historic collections of succulent plants in the Botanical garden trace the web of these relationships and keep their memory.

Carnegiea gigantea

This plant, in the Cactaceae family, can reach a considerable size. It lives wild in the desert of Sonora, which extends over a vast area of the Mexican region with the same name, plus Arizona and California. It reaches reproductive maturity after 30 to 35 years, and a 50 to 70 year old individual can produce as many as 100 fruits in a season. The native populations eat the fruit and have developed various procedures to preserve it (and the seeds), as dried fruit or syrup, as long as possible. The seeds are used dry, and ground to obtain a flour used to make flatbread. The seasonal harvesting of the Carnegiea fruits takes place with various rituals and methods, and the links between this plant and the native populations are so strong that the calendar of the local people — the Tohono O’odham — follows its growth stages and ripening of the fruit month by month. An example of the medical use of succulent plants is, on the other hand, the Aloaceae family, including Aloe vera and A. arborescens. Used in ancient times as a cicatrizing and soothing agent, these plants are the focus today of renewed interest from medical science, which is experimenting with their use to produce anti-tumor drugs.

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