Exotic plants and landscape: how much is our landscape “natural”?

29 April 2017

The exotic plants introduced in Italy by man’s intervention, over the history, have deeply affected ourperception of what we are used to consider the “natural” landscape.

It looks like a typical Tuscanlandscape: actually we are inSouth Africa!

Paesaggio naturale: siete sicuri?

By looking at certain places in Tuscany, but also, more generally, in Italy, we are used to consider the landscape as “natural”. The landscape that surround us today is characterized by an high level of biodiversity. That biodiversity, tough, hasn’t its root in the natural flora of Italy, rather in the fact that over the centuries man has introduced many foreign plants. Those “exotic plants” have characterized our landscape to such degree that now we are under the impression that what surround us has to be natural. Landscape is actually the result of man’s actions, and that transformation happened during the history in order to satisfy his own necessities. Let’s recall briefly the main stages of exotic plant’s introduction.

L’introduzione delle piante esotiche nell’antichità

Before the advent of agriculture, in the world of vegetables there were just natural migrations. Those were due climate changes, or some other environmental factor which pushed plants towards new lands, thanks to seed dispersal and the transport by wind, water or animals. Man spent most of his time by hunting and gathering, with little resources available for other activities.
By the end of Neolithic man began to select, grow, transport ,and sell plants to satisfy his commercial or dietary needs. And thanks to the introduction of plants originating from other countries, man shaped the landscape where we live. Among the first sedentary civilizations, domestication of plants and animals has given the start toc hanges in the natural environment that are still ongoing.

Therefore the discovery of agriculture represents the first big step towards the modifications of the natural distribution of plants. That is the point when we can start to talk about “exotic plants”, in other words plants originating in a different geographical location, that are introduced in a new place by the man in order to satisfy his own needs. E. Hyams in fact entitled his book on history of domestication:

“Plants in Service of Man”

hinting to the enormous impact that agriculture and livestock had on natural flora and fauna. Several plants from middle east were already introduced during the Roman empire for production but also for ornamental reasons, as for sycamore, oleander, and sweet cherry. Pliny, harshly critic towards his contemporaries,deprecated the ostentation of exotic plants in gardens:

“Who wouldn’t be surprised knowing that a tree has been imported from a foreign country just to give someshadow? It’s the sycamore…”

Citrus collection in Castello’s Villa Reale near Florence

From botanic collections to colonialism

During the Middle ages the introduction of exotic plants slows down, due the reduction of commercial exchanges.The forests expanded as much as the agricultural landscape becomes impoverished.

During Renaissance some plants are “rediscovered”, thanks to the botanical collecting practiced by the richest families. A clear example of that is Castello’s Villa Reale near Florence, where dozens of citrus cultivars are kept.

The discovery of America is, in this sense, another key point in exotic plants history, due to the fact that since that moment two different ecosystems, previously divided from an ocean, come in contact and start exchanging plants due man’s intervention.

During colonialism commercial routes increase, till they engulf the entire planet,reaching far and unknown countries, where new botanical species are discovered. Tropical plants arrive in Europe for every country and there, thanks to steel and glass, the first green houses are built. The tepidarium of the Horticulture Garden, built at the and of the 1800 by the Tuscan Horticulture Society, it’s an example of those nineteen century structures.

Tepidarium in the HorticultureGarden in Florence

The “natural landscape” in nineteen century paintings

The world of art also contributes, especially with nineteen century paintings, in spreading the idea of a natural landscape which isn’t in fact natural at all. There are many examples of painting with exotic plants that wereactually introduced by the man in Europe, used to give the image of the “natural” European landscape. For example, in the “Lake of Avernus” painting by Jakob Philipp Hackert, an agave, a pine and a palm tree are used to characterize the Mediterranean landscape. Those are plants coming from countries that are more or less close;agave for instance was imported from America.

Jacob Philip Hackert, The Lake of Avernus

Exotic plants and invasive species

After a general overview of exotic plants introduction by the hand of man, it’s obvious that man’s intervention had avery strong impact on natural landscape. This transformation has, not only increased the biodiversity of our ecosystems, but also created huge imbalances in their ecologies. Plants originating in different ecosystems havefound good ecological conditions and have spread enormously.

Introducing exotic plants isn’t a problem on its own, unless the introduced plants become invasive. Those concepts may look similar, but they shouldn’t be confused. Invasive plants do in fact have a precise set of characteristics, that differentiate them from native plants, which in turn suffer from their very effective competition.
They are plants with a very quick growth, usually capable to produce abundant seeds, with an early flowering, self pollinating and/or capable of asexual reproduction. They have been introduced in a favorable ecosystem by mistake or voluntarily, and they have been capable to replace native plants. This may lead to severe consequences, especially in agriculture. An example of those plants is Robinia pseudoacacia (black locust), that has been spread in Italy to help in stabilizing cliffs, but later has proven itself a strongly invasive plant.

This article is a summary of the speech held by Alberto Giuntoli during the conference at the Botanica 2017 event in
Villa Caruso, Lastra a Signa.