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Today’s extant plant forms reflect a complex evolutionary “work” that has taken place over more than 400 million years, during which plants have deployed cunning strategies to be able to adapt to various types of environments, managing to survive and reproduce even in the most climatically severe places. But life began in the water…

Every living organism on this planet has an aquatic past, and even plants began their journey to the landmasses timidly, appearing out of the water when they were still modest algae, simple but daring: for they were able to withstand continuous and alternating surfacing and diving by adapting to a life “amphibious“.

Slowly, the land was inhabited by slender seedlings that shared their territory with more robust and overbearing species; evolution shaped these ancient creatures, which moved further and further toward the dry land until they colonized it, first in the areas adjoining freshwater bodies of water, later penetrating to the innermost spaces where water was entirely absent.
These “shifts,” which occurred over millions of years, shaped the plant organisms of yesteryear “transforming” them slowly into the various forms that populate our planet today, from the low and reserved mosses, still bound to the wettest environments, to the tall and superb trees that with their sophisticated woody stems pushed their green foliage ever higher.

Tree plants without flowers, the gymnosperms, and those with flowers, the angiosperms, were differentiated.
That of the flower was indeed a brilliant invention, but let’s take a step back in time. The first problem to be faced, once land was conquered, was to retain the water that was no longer so readily available on land. Cutin, a hydrophobic waxy substance, served to waterproof the outermost tissues of plants, thus helping them retain water inside.

Another problem was that of having to stand! Out of the water they lacked the buoyancy that previously allowed them to float: something had to be invented to be self-sustaining, and lignin, a complex organic polymer, was “patented” by plants to solve this very problem: by impregnating plant tissues, it made them rigid and strong.

In doing so, plants not only conquered dry land and thus more and more space and resources but also began to grow taller in order to better reach the sunlight. This resulted in the need to develop a sophisticated system for conducting the lymph, the xylem and phloem tissues, which could now be transported dozens of meters!

But back to the angiosperms: appearing around 130 million years ago (according to some studies even older), they had an evolutionary enlightenment with the invention of the flower and with it established an alliance with the animal kingdom that endures to this day in the most creative and curious forms.

Insects, attracted by the colors and smells of the flowers, settled on them allowing pollination and thus fertilization: that was it, plants had found a way to reproduce by investing very few energy resources, no more pollen wasted in the wind, millions of pollen grains scattered who knows where. With the help of insects, plants made sure that their genes ended up in the right place and their species perpetuated on the earth.

A long journey that of plants, no doubt about it, a journey still in progress that looks toward the future in the conquest of ever more distant destinations and spaces, through space orbiting stations, where some plant species are being tested in order to perhaps one day take root on the soil of other planets.

Among the many technological achievements that have marked the 20th century, the space race is among the most fascinating: we have succeeded in overcoming the gravitational pull of our planet to take men and machines into Earth orbit and to the Moon; for the future, we are aiming straight for the first manned mission bound for Mars. Even in this adventure, plants will accompany us!

The International Space Station(ISS) has been operating continuously for more than twenty years in Earth orbit, hosting teams of astronauts and scientists on research missions lasting up to several months; among the purposes of this research is the development of technologies that can keep a crew alive on missions beyond theEarth orbit.

For years, space agencies, NASA and ESA above all, have been conducting experiments to understand whether and how plants grow in a micro-gravity environment, growing plants on the ISS for a variety of reasons, including:

• test the best species that can withstand artificial lighting and feeding conditions so that they are ready to run multi-year greenhouses on the planet Mars;
• select plant varieties that support the action of mechanical filters in cleaning the air inside the Space Station, in future spacecraft for long-duration travel, and in permanent settlements, whether on the Moon or Mars;
• vary the diet of the crew in Earth orbit by including, among the bags of freeze-dried roasts and lasagna, a good fresh salad;
• improve the psychological condition: contact with flowers and leaves seems to have a very positive impact on the mood of astronauts, who retain only a vague memory of Earth’s flora for months.

The first steps of the orbital botany date back to the early 1980s of last century: the record for the first plant grown in space belongs to the crew of the Russian space station Salyut-7; Soviet cosmonauts managed to complete the entire life cycle of a Arabidopsis thaliana: seeds were planted that germinated and completed the growth process by forming reproductive organs and finally completed the fertilization, embryogenesis and maturation stage. Full success, all in just forty days!

Instead, over the past decade, it has been the Americans at NASA who have pursued the “space gardening“: in particular, astronaut Donald Pettit grew a small vegetable garden during his five-month stay aboard theISS: using ordinary plastic zip-lock bags, Pettit was able to sprout broccoli, sunflower and zucchini seedlings, which, however, did not grow enough to bear fruit, but only to provide a soothing “pastime.”

But Nasa did not give up, and after a short time launched a space agriculture program, named VEGGIE, based on theaeroponics, i.e., a process of greenhouse development of plants without the use of soil, but artificially supported and with nutrition provided by misting systems of water enriched with mineral fertilizers, which directly invests the root system.
The VEGGIE project greenhouse is still small, about the size of a kitchen oven, but has the advantage of being both collapsible and expandable; light is provided by a panel with red, green and blue LEDs.

The first seeds to be planted on the ISS were those of romaine lettuce and zinnia: the latter, produces a flower that is very sensitive to environmental parameters and light variations with a life cycle of 60 to 80 days; a very difficult plant to grow successfully, but an excellent precursor to the tomato and bell pepper plants that will be planted soon on the Station. Romaine lettuce has been examined providing positive results to various biochemical tests, and is currently consumed by astronauts along with radishes, lentils, green lettuce, and Chinese cabbage, all of which are produced in space!

Plants can also solve another problem typical not only of the ISS, but also of our homes and offices: limited cubage and an almost entirely plastic building produce a high concentration of VOC (English acronym for “volatile organic compounds“), namely benzene, formaldehyde, trichloroethylene and other harmful substances emitted from glues, paints, pipes and joints.
To make the air in the spacecraft more breathable, Nasa has started the program “Clean Air Study” (“clean air study”), to measure how much and what volatile solvents can be absorbed by ornamental plants; about 20 common indoor plants were tested, including ivy, pothos, aloe, dracaena, spatiphyllum, and sanseveria.

The results suggest that, in addition to absorbing carbon dioxide and releasing oxygen through photosynthesis, these species act as a “bio-filter,” removing the pollutants listed above in amounts up to ten times higher than the legal limits in some countries and recommended by the World Health Organization!
Sources of key nutrients and active ingredients that have always been used in medicine, dispensers of soothing well-being and also purifiers of the air in our homes: there are many benefits we can gain by surrounding ourselves with our green friends from the plant world.

Despite the fact that most human beings do not adopt a strictly vegetarian diet, plants in the diet are not only plentiful, but are consumed in all their parts, even the most unusual ones, from root to flower!

The plant-based foods on our tables are numerous and we have always consumed a great deal of them, as they bring essential nutritional elements to our diet: in addition to carbohydrates and protein, fruits and vegetables are rich in fiber, vitamins, minerals and water.

When we think of plant foods, the color green immediately comes to mind because we associate it with eating the leaves, the key organs for photosynthesis; lettuces of various types and herbs are a clear example. But the most curious aspect of plant nutrition is that it involves the consumption of all other plant organs-we really are capable of eating any plant-derived structure!
For example of the species Daucus carota, the carrot, we consume the roots, which in this species are particularly tasty, sweet-tasting and typically orange in color, but there are also other colors: the purple ones are very tasty and also preferable for those who tend to a diet with less sugar.

Do you know about radishes? Have you ever wondered which part of the plant they correspond to? Radish is a brassicacea of which we consume the hypocotyl , which is the tract of the stem between the aerial part of the plant and its root, which in this case is particularly enlarged and succulent.
One of the foods that reigns on all tables and that we cook in so many different ways is a keg! Yes, we are talking about the plant organ that supports branches and leaves; the stem we are talking about, however, is different because it is modified to fulfill the function of an underground organ of water and starch reserve, a reserve from which the plant draws when it needs to regenerate the aerial part; it is technically a tuber. And it is the most beloved tuber in the kitchen: the potato!
From an instead aerial stem, that of Saccharum officinarum, we derive a syrupy fluid: sugar.
We are able to extract food products even from the arid, woody barks: there is a spice that is used in both sweet and savory recipes and is made, just think, from the bark! Branches and stems of Cinnamomum sp., a species of Asian origin, are processed to extract the inner part of the bark from which cinnamon is made.

We even consume the petioles, which are the leaf-bearing structures that connect the leaves to the stem; an example isApium graveolens, the common celery.
Have you ever eaten buds? Definitely! I capers, which we gladly use to season some typical dishes of our Mediterranean cuisine, are the flowers of the species Capparis spinosa, and we consume them before theantèsi floral, that is, before the flower opens initiating the reproductive season; if we did not eat them, these buds would become very showy and elegant flowers.
Artichokes are actually buds as well, particularly of the species Cynara cardunculus, subspecies scolymus, and again our gluttony deprives us of the spectacle of their beautiful purple inflorescences.
Before anthesis, these flowers are completely enclosed within bracts, that is, modified leaves that serve a protective function in this case.
The artichoke part we consume is represented precisely by the base of the bracts as well asthe floral receptacle , that is, the axis on which all parts of the flower are placed.
But even after antèsi some flowers are present on our tables: fried pumpkin ones for example, but also primroses, violets, roses and daisies enrich omelettes, pies, risottos and salads. Needless to say, in each of the cases just listed, all we are doing is eating the sexual organ of the plant!

Fruits develop from the female part of the fertilized flower, and we consume all the fleshy ones, which are so many that they are divided into several categories of which we recall the main ones: drupes e berries ; stone fruits, whose fruit containsonly one seed, include some of the most widely grown fruit trees in our regions, such as theapricot and peach tree, plants native to China.
Among the berries, the fruit of which contains more semi, we like to mention some vegetables such as eggplant and peppers, which are respectively the fruits of the species Solanum melongena and Capsicum annuum, both belonging to the Solanaceae family; the word “vegetable” is the generic name by which “horticultural” plants, i.e., vegetable garden plants, are commonly referred to, regardless of which part of the plant is used.

But it doesn’t end there! Our gluttony also leads us to eat the spreading structures of plant species, containing the embryo that will give birth to the new plant: seeds! We eat a variety of them and consume the products derived from them.
What we commonly call “dried fruit,” is actually in some cases not even fruit: for example, peanuts or pistachios are also seeds found inside the fruits of Arachis hypogaea and Pistacia vera, respectively.
Processing the seeds of Theobroma cacao, a small tree native to Central America, yields a brown powder with a very bitter taste, cocoa, from which we get a food we could never give up: chocolate.
Many seeds we find as spices to flavor and season our dishes: cumin, fennel, and pepper are the most common ones.

Earlier we talked about the delicate plant-animal balance; we want to recall here the importance of this relationship as it is closely related to our nutrition: a great many fruits develop only through the intervention of the pollinating insects; during their tireless work, bees, butterflies, wasps and many other insects not only help plants reproduce but also help us humans: without them we would be forced to carry out a artificial pollination, that is, by hand or through machines.

The concern due to the disappearance of some wild insects is legitimate when we consider their contribution to the reproduction of so many species and the consequent reduction in plant biodiversity.

Compared to the imaginative clothes worn by plants to better adapt to natural environments, those imposed by humans reflect the need on the part of humans to indulge their own desires. What appears stupendous in our eyes can be vain, if not even counterproductive “in the eyes” of a plant!
In nature, it is not necessary to be beautiful; instead, it is useful to be able to adapt.

Who hasn’t enjoyed at least once in their life the wonderful roses with variegated colors and sweet scents! Well, know that the rose selected by nature and not by man is very different but no less beautiful!
The wild rose has only five petals but has numerous stamens, the pollen-rich male reproductive structures of the flower. One fine day, as a result of a random mutation, a rose plant was born whose flowers had fewer stamens but a greater number of petals; this feature was highly appreciated from an aesthetic point of view, and so man decided to cultivate and propagate, vegetatively, the rose plant with the most beautiful flowers.

Today there are a great many types of artificially selected roses. The more petals they have the more beautiful they are, too bad they couldn’t reproduce in the wild! In the angiosperms flowers, which represent the sex organs, exhibit characteristics such as fragrance, color, and symmetry that are functional for reproduction, so as to promote pollen dispersal through various modes, the most recurrent of which are theanemogamy, in which the wind causes pollen to reach flowers of the same species, or theentomogamy, which uses the insect as a vector for pollination.

Interestingly, although beetles already existed to provide pollination for some gymnosperms, the appearance of the main pollinating insects (hymenoptera, lepidoptera and diptera) coincided with the appearance of flowering plants in the middle of the Mesozoic era; from there on, pollinators and flowers embarked on a co-evolutionary process that continues to this day.

There are some insects, such as flies, that flock in large numbers to the irresistible call of species whose flowers give off odors that are intoxicating to them, but instead very unpleasant to our noses! The plant cares little about being attractive to humans, and at this point we can be sure that what we desire does not match the needs of natural plant species.
It is also true, however, that we are able to “create” plant varieties that are useful for our purposes, and it is thanks to this ability that today we have at our disposal a large number of species that we use not only for ornamental purposes, as in the aforementioned case of the rose; think, for example, of the importance of certain plants in food, or of the fact that the fabrics of many of the garments we wear (cotton, linen…) are the result of man’s ability to cultivate useful plants and process their textile fibers.

The needs of humans and nature, often in antithesis, have shaped the plant landscape by creating highly differentiated areas, sometimes even in close contact: if we take a walk in a cultivated field at the edge of a forest, we immediately notice the difference between the orderly monotony of agricultural rows and the spontaneous heterogeneous tangles of the plant organisms occupying every free space, where slender herbaceous plants, shrubs and large trees coexist in a great and harmonious variety of botanical forms.
Obviously, admiring a well-maintained flower garden cannot help but be fascinated by it, but we must consider how it consists of species that have been cultivated for ornamental purposes for a long time, and are thus adapted to artificial conditions, and often totally distorted from their original context.

Many of the species we see growing in our parks and gardens come from other countries and, even if well acclimatized, certainly do not represent typical vegetation, perhaps less showy but more characteristic than exotic. It should be pointed out in this regard, that many introduced species have become invasive, that is, they have occupied the territory where native species (species that originated and evolved in our territory) once grew wild.

Even plants grown for food have undergone a slow transformation: many of the fruits we consume would grow smaller in size in the wild. Plants have no interest in producing fruits that are too big and heavy; the important thing is that they are full of useful seeds to carry on their genes! The interest of every living organism is to perpetuate its species; therefore, the fruit of a plant must, if anything, be clearly visible when ripe, such as the small berries that become red when ripe and attract the greedy birds that facilitate their dissemination.
If left to grow wildly, the plants would just follow “their instincts”: they would flower when the time is right, for example, when pollinators are present, would produce fruit when the temperature and humidity are such as to allow it to ripen, at the necessary times, without haste; tree branches would stretch in their preferred direction, the one that best exposes their leaves to sunlight; a wonderful multicolored carpet of leaves of seasonal species would accumulate on the ground; new seedlings would grow only where environmental conditions permit, and, of course, the most suitable ones would be selected, able to fight for the available space and resources.

The lucky ones would be in the right place at the right time and with the right genes, and would grow vigorously until they became ripe for reproduction. In some places on Earth, which are unfortunately becoming increasingly small, this is still happening. We should leave more room for nature to take its own course and at the same time continue to use “our” spaces to make the desired selection but with a little more care, remembering that our control over nature is only temporary.

Have you ever thought how difficult it would be to escape an enemy if we were unable to escape? How can an organism avoid predation if it lives anchored to the ground? Plants have solved this problem very cleverly, in some cases even deviously…

In the course of evolution, diversified strategies have been developed in the plant world to cope with natural hazards. Some plants defend themselves by covering themselves with thorns or spines, others make themselves invisible by camouflaging themselves in their natural environment; the ones we will discuss here are hiding a secret: their defense weapons are not immediately visible, and by the time you discover them it may be too late! These species accumulate toxic substances in their organs to deter potential herbivores, including humans!

Science has long wondered about the potential of these plant-derived compounds to treat the human body, analyzing their active ingredients for use in therapeutic purposes. But where is the line between danger of death and salvation of life? When does a botanical species heal and when does it kill? The genius of the Greeks baptized drugs with the word “pharmakon,” which means both medicine and poison: it depends on the awareness, the occasion and the individual whether one thing overflows into the other!

For plants, the production of chemicals has a very important ecological significance, as it enables them to communicate differentially with other organisms: with useful ones by inviting them to come closer, think, for example, of the smell that certain flowers give off by attracting pollinators to them; in other cases, the plant intends to communicate “stay away,” addressing potentially harmful animals. These messages are formulated through the production of secondary metabolites, i.e., compounds that are not essential for growth and development but have an important ecological function.

Studies of plant phytochemistry have shown considerable biochemical diversity. About 40 percent of single-molecular (i.e., consisting of a single active ingredient) drugs are derived directly or indirectly from plants. While the use of medicinal plants has declined in developing countries as a result of the emergence of synthetic “potent drugs,” ethnobotany is still used in poor countries as the only resource for finding remedies for certain diseases. However, it should be pointed out that synthetic drugs are the end product of the processing of active ingredients isolated from plants and reproduced by chemical synthesis.

We should not think that poisonous plants are far away from us: some we easily encounter during a walk, think of the very common ivy, Hedera helix; that species with its elegant climbing habit contains several toxic compounds that can create some problems by accidental ingestion.

Some drugs we routinely use without knowing it: coffee for example is nothing more than the product of processing the seeds of Coffea arabica, a species that contains a natural central nervous system stimulant: caffeine!

Very often more than one toxic substance is found in the same species, and sometimes these accumulate in certain organs of the plant rather than in others. Among the most poisonous chemical compounds of plant origin are alkaloids, nitrogenous substances responsible for serious toxic effects, and glucosides, substances composed of one or more sugars and a non-sugar part of various kinds. Both of these categories of chemical compounds are characterized both by their toxic effects on humans and other animals and by their applications in the pharmaceutical field; let us look at some examples.
Datura stramonium is an herbaceous plant belonging to the Solanaceae family, widespread in various parts of the world. The plant is known as “devil’s herb” because it has narcotic and hallucinogenic properties that induce a trance-like state; for this reason, in some countries, stramonium is used in shamanism.

All parts of the plant contain alkaloids such as hyoscyamine, atropine and scopolamine. Stramonium poisoning can result in tachycardia, hypertension, psychomotor excitation, delirium, and in rare cases death. Stramonium is used therapeutically particularly as an asthma remedy. Other properties associated with this plant are antimicrobial and anti-inflammatory.

The yew, Taxus baccata, a tree plant belonging to the Taxaceae family, is a gymnosperm also distributed in Europe where it is used mainly in parks for ornamental purposes. The yew tree is so poisonous that it is called the “tree of death”! All parts of the tree are poisonous, except for the aril (false tegument that wraps the seeds of some gymnosperms), and this is no accident: the tree needs help to disperse its seeds and cannot poison even those who make themselves indispensable for this purpose: birds! These digest the pulp but not the seed which comes out intact and is released through the feces of the animal, which, flying, carries it considerable distances allowing the plant to expand its horizons!

The alkaloid present in the greatest quantity in the yew is taxin, but other alkaloids are also present including taxol.Studies on its anticancer properties have highlighted its role in cancer treatment, which is why this substance has entered international protocols for chemotherapy of some forms of carcinoma. However, this plant can prove fatal: if ingested, in fact, taxin is absorbed very quickly by the digestive system, causing toxic effects especially at the cardiovascular level.

Oleander, Nerium oleander, a shrubby or arborescent plant belonging to the Apocynaceae family, is an evergreen species with beautiful fragrant flowers, which is why it is widely used to decorate gardens, parks and even streets. It is widespread in Mediterranean regions and is poisonous throughout; however, the leaves contain a higher concentration of toxic substances: these are glycosides with cardiotoxic action that, if ingested, damage the heart muscle. Symptoms of poisoning range from vomiting to cardiac arrest. Oleandrin, a cardiotonic glycoside, is used in preparations for the treatment of heart problems.

The risk of coming into contact with poisonous plants is high because of the many toxic plant species used for ornamental purposes. Ingestion of parts of these plants is an accidental event, but unfortunately, cases of poisoning children and even pets are common. However, even moving away from the urban environment, there is no shortage of risks: by going in search of wild plants we could easily get confused. Hemlock, Conium maculatum, famous for killing the philosopher Socrates, is an extremely poisonous plant in every part; it belongs to the Apiaceae family which is characterized by umbrella-like inflorescences that are very similar in different species.

Hemlock can be easily confused with fennel because of the similarity of the fruits, with parsley because of the similar leaf structure, and with parsnip because of the presence of a resembling root, the difference being that a few grams of the root of C. maculatum Are capable of killing a man! Hemlock gives off a bad smell, but unfortunately, not everyone has a well-developed sense of smell.

• maculatum contains various alkaloids that exhibit very high toxic activity against many other animals including sheep, cattle, birds and insects. In short, the plant defends itself well! the alkaloids present in hemlock act on the nervous system causing death by respiratory arrest however, the same compounds, would seem to be indicated to treat various disorders including those of a neurological nature.

We have given only a few significant examples of plants that are dangerous and at the same time useful, but we want to point out that the number of potentially poisonous species is very large, so we suggest that we always approach plants with respect and awareness, as we would in front of animals we do not know.