How the exotic plants came to Venice: Our botanical garden heritage

In the Middle Ages, and until the 18th century, Venice was the city boasting most botanical gardens in the world, allegedly there were more than 500 botanical gardens ... When you first come to Venice, this may be hard to believe because one of your first impressions may be that Venice is a city consisting white stone and marmor ... But these gardens did exist, and there are still numerous traces across our lagoon city today. The Venetian botanical gardens housed precious plant species that arrived from the sea voyages right into the palace gardens of many Venetian noble families. Some gardens, and even traces of the former splendid plant collections, have survived to this day - though, as they are housed in private gardens, they are not accessible to the public. Other former botanical gardens survive as hotel gardens, such as the Giardino Rizzo Patarol (now Gran Hotel dei Dogi), and the gardens of the Hotel Cipriani on the Giudecca island. And sometimes former noble families' gardens are accessible as they belong to palaces converted to museums and art galleries, such as Ca' Rezzonico and Querini-Stampaglia.
A private palace garden next to the Accademia Bridge. In Spring, their roseti (rose garden) is really colorful and parts of it can be seen if you walk up a bit further the Bridge.
So when Venice, or the Rivus Altus group of islands was first settled, as early as 425 AD according to the legend of the "Birthday of Venice", in particular the outer islands of this group of 118 islets were settled, in particular by monasteries, with the purpose of creating vegetable gardens and orchards.
Pianta prospettica di Venezia, by Jacopo de' Barbari, 1500, small botanical garden paradises between the palaces: Click here to view more
At the same time, the first noble families of Venice, the famiglie apostoliche, included gardens per divertimenti  into their properties. From their palaces' upper floor windows (piano nobile), they were used to the spectacular views that their trophy plants gave them, growing lush in their garden below. And when Venice became involved in the trade business with the Byzantine Empire, Venetian noble families merchants came across the Levante influence, from architecture and arts to gardening and botanical treasures. The Venetian merchants, exchanging goods from the lagoon (salt, salted fish etc) for luxurious goods from the Levante, from their sea voyages brought back not only spices, silk, precious stones and other luxuries destined for European markets, but also a host of exotic plants, from seeds to young plants and off-shots. Some of these plants took to the salty soil of the lagoon quite well ...
Exotic treasures hidden behind high walls: Kaki and passilfora 
And it was these noble families that concurred to create private garden paradises. Soon, Venice became dotted with gardens, from the 8th century AD onwards. In addition to fruit and vegetable gardens tended by monasteries, that also served to feed the Venetians, in the center of town, gardens were created that fulfilled decorative purposes and at the same time represented gardening laboratories for experimenting with tropical plants by growing and crossing them, to the curious Venetian noble families and other merchant families that had become rich through trading with the Levante region (Eastern Mediterranean, North Africa).
This so-called original Venetian first nobility - the famiglie apostoliche were: Badoer (Partecipazio), Barozzi, Contarini, Dandolo, Falier, Gradenigo, Memmo, Michiel, Morosini, Polani, Sanudo, and Tiepolo. 
Hidden behind walls - private palace gardens, here a picture of the Rio dell'Osmarin in Castello
One could say that the curious and adventuruous gardening-fixed noble families and merchants of the Serenissima Republic of Venice between the 11th and 14th century represented the forerunners for what would be later called esotismo - here I mean a way of life including exotic plants to create exceptional gardens: 
Giardino Rizzo Patarol, at the Hotel Dei Dogi next to the Church Madonna dell'Orto (Cannaregio)
In his encyclopedia "Venetia. Città nobilissima e singolare", published in 1581, Francesco Sansovino (son of architect Jacopo Sansovino) describes the Venice of the 15th century as a town "interspersed with gardens inviting to take a relaxing break". Gardens were created in the midst of Venice, where to spend restful afternoons and evenings, whereas on the "outskirts" islands (Giudecca, northern islets of Cannaregio, northern and eastern islands of Castello) one would have found mostly the monastery gardens, vegetable gardens and orchards, interspersed with reedy and grassy areas and little puddles and lakes (still recalled today as "piscine" eg Piscina di Frezzeria).
Giardino Rizzo-Patarol
Typical plants that represented a background for all the lush tropical plants of the past looked like this garden in the picture above: roses, vines, cedars, cypresses, intermingled with special tropical treasures: such as this - the clivias I found in a secluded, very moist but warm spot in a secret garden (from a private hothouse) ...
Garden layouts were symmetrical and repetitive all over Venice: First, one had to cross the paved cortile (courtyard) complete with pozzo (fountain used to collect rain water). From here, a few stone steps led into a slightly elevated garden level where the decorative plants were housed, intersected by a gravel walk leading o the other end of the garden, across a shrubs- grown area, including the rose garden, to the porta all'acqua and the canal entrance of the property. Near that backward entrance, usually a pergolato, a pergola-covered part of the garden was located, mostly overgrown with vines (today, this would often be glicine - wisteria !!). 
This is what I mean: picture of a backward entrance to a garden
And today, I notice that the many traveling Venetians, and they love to travel in particular now in the first two months of a new year, ever more often in the last 10 years or so, bring back new ideas and inspirations for their gardens, and sometimes plants and seeds to try out in those gardens that had often been overlooked up to that time. Visitors could see by now how well the new exotic plants take to the lagoon climate, exactly as they did centuries ago, thanks to the mild sea climate (though one has to take care and often has to protect plants from the salty soil). 
Near Campo SS Apostoli, Strada Nova