Many of the trees and shrubs that we look on as «our own» have actually blown in from distant lands, taken root and, having adapted to local conditions, enriched the country’s flora. Meanwhile, for the past 6,000 years, the human activity of farming has affected natural plant growth, transforming large tracts of land and, along with the development of farming methods and the discovery of new regions in the world, resulted in the introduction of new species from other parts of the globe. In Greece, this process began with the military campaigns of Alexander the Great (335-324 BC) and peaked with the Arab conquests of European territory. Two other major historic events, the first navigation of the Cape of Good Hope in 1468 and the European discovery of America in 1492 resulted in the further enrichment of Mediterranean flora with dozens of trees and shrubs that were beneficial for human survival. Biologist Grigoris Tsounis spoke to Kathimerini about the way some of these plants have become part of Greece’s plant heritage. From Theophrastus’ time Rice, unknown in ancient Greece, was referred to by Theophrastus (372-287 BC) as an Indian plant. A student of and successor to Aristotle, Theophrastus expanded his mentor’s research using botanical reports compiled during and after Alexander’s campaign of Asia. Theophrastus’ work «On Plant Histories and Plant Origins» includes valuable observations and information on the movement of plants in relation to the sun, on animal camouflage and botanic geography, which formed the core of scientific knowledge in the fields of phytology and botany up until the late Middle Ages. Cotton, unknown in Greece until Alexander’s campaigns, was used in the Indus river basin as a weaving yarn 3,000 years before Christ but did not appear in the Byzantine Empire or the rest of Europe until the early Christian era. The Arabs were the first to try planting cotton in Europe in the 10th century and introduced sugar cane to Crete and Rhodes at about the same time. Many fruit-bearing trees and shrubs which are now considered part of the Mediterranean ecosystem and its peoples’ dietary habits were unknown in ancient times. Lemon and bitter orange (Citrus aurantium) trees, commonly found in most Greek towns as well as in the countryside, were brought here by the Arabs via Spain from tropical areas in southeast Asia. The bitter orange is referred to in texts by Theophrastus. Much later, in about AD 1500, the sweet orange (Citrus sinensis) tree was brought to southern Europe by Portuguese seafarers who had rounded the Cape of Good Hope to reach the East Indies and China. Another popular tree in Greece, the mulberry, was brought from China in the sixth century by Greek Orthodox monks. Barbary figs and Agave americana (the century plant, ubiquitous in archaeological sites in Athens, such as the Ancient Agora and the Acropolis), arrived in Europe after the discovery of the New World. It is said that Columbus himself brought the Barbary fig to Europe. The European discovery of America was a turning point for the introduction of plant species into Europe. Many species of American flora were brought to the Mediterranean where they found climatic conditions similar to their place of origin. The introduction of corn, potatoes, peppers and tomatoes also dates from this period. It was during the 16th century that tobacco, a plant now grown widely in Greece, was brought to Europe. The Ailanthus glandulosa, called «tree of heaven» by the Chinese, reached Greece from eastern Asia in the 18th century. As it propagates easily and rapidly, it is found everywhere, from roadsides to the ruins of old buildings – anywhere in fact where it can find a bit of soil to send down roots. It colonizes rapidly, is not attacked by pests, and is particularly resistant to dust and smog. It came to Greece during the Ottoman rule and became well acclimatized. One wonders why it has not been considered for use in the reforestation of areas destroyed by forest fires and in preventing erosion from flooding, though its leaves give out a rather unpleasant smell, mainly during the evening hours. Most varieties of palm trees are also imports, although not «Theophrastus’ palm» (Phoenix theophrasti) which flourishes in some parts of Crete, where Theophrastus was the first to record them. The eucalyptus is from far-off Australia where it can reach heights of up to 100 meters. In the Mediterranean, it does not usually grow higher than the average tall tree. Early in the 20th century, it was used in marshy areas and as protection against malaria, as the essential oils in its leaves repel mosquitoes. Acacias are also native to Australia, as are mimosas (Acacia dealbata), a variety of acacia that does not reach great heights. It is another frequent occupant of archaeological sites around Athens, particularly the Kerameikos. The banana tree was imported from Africa. Although rarely found in continental Greece, it is cultivated successfully on Crete and Cyprus. Many decorative plants such as the yucca and bougainvillea come from America. Honeysuckle and jasmine are from China.