It is estimated that in antiquity, at the time of the Romans 1,300 - 1,400 different plant species were known. Even closely related plants could be distinguished, although the arbitrary naming gave way to many errors and misunderstandings. From now on any scientific activity stagnated for centuries. Neither were new observations made, nor did new ideas develope. The influence of the Arabs on the culture of the occident had but little stimulating effects on botany, though they confronted Europe with the literature of antiquity. One of their most important inventions, destillation, was introduced to botanical research only centuries later. Among the opinions that prevailed in Arab culture was the following (cited from F. DIETERIER: Die Naturanschauung und Naturphilosophie der Araber im 10. Jahrhundert, Berlin 1861):
"On the lowest level is the ruinęs green (i.e. lichens and moss) that is merely dust pressed together. On the highest level is the palm tree. It is an animal plant, that does not resemble other plants in some actions and conditions, although its body stays plant-like. With the palm tree the acting (male) force is separated from the suffering (female) force. With other plants these forces are not detached."
The observation that the female and the male genders of the palm are separated goes back to antiquity. Both ARISTOTLE and THEOPHRASTUS were aware of this fact, but they were not able to draw any conclusions or to examine whether this feature could be found with other plants, too.
The beginning of science in the West was arduous and dragged on for centuries. Plants were for the first time catalogued in the capitularies of CHARLEMAGNE (771 - 814). These records are regulations concerning the instruction of the youth, the improvement of agriculture and the lay-out of gardens. English Benedictines made an inventory of the plants grown in imperial gardens of Lower Palatine. The inventories contain 6-7 different cereals, 17-18 varieties of fruits, 38 varieties of vegetables and herbs, 35-37 different medicinal plants and 5 plant species used for dyeing and the production of fabrics. Although the influence of the Arab culture as represented by the Arabs ruling in Spain till the beginning of the 14th century on Western science was but small that on the attitude of the minds was considerably larger. Monks, priests and scholars went on pilgrimages to Spain to visit its large libraries (that of Cordoba had since 755 660,000 volumes) and to study the works of antiquity there. Many works were translated into Latin. In the course of this - and in that of the numerous copies made - a lot of mistakes and distortions slipped in. Confusion was especially generated by the way plants' names were used. The knowledge that the flora of Central Europe is of a fundamentally different nature than that of the Mediterranean common to us today was missing. It was expected, and for many centuries to come, that the plants reviewed by PLINY and, after works of ARISTOTLE and THEOPHRASTUS became known, the plants reviewed by them, too, had also to exist in Central Europe. It was further assumed that the lists made in antiquity of plants and the descriptions given of them were complete. First signs of original observations go back to the abbess HILDEGARD VON BINGEN (1099 - 1179). She gave descriptions of more than 300 different plants and put German names on them, though she was writing, as was usual, in Latin. Some of these names have been used in the local dialect (Rhineland) up until the last century.
SAINT ALBERT THE GREAT (1193 (?) - 1280) from Lauingen upon the Danube was a widely travelled clergyman and scholar. He is thought to be the rediscoverer of scientific botany. In his work, that deals only in a small section with plants is the body of thought of antiquity mirrored; still, it does represent the first descriptional work on the flora of Europe and it became both model and precursor of western literature (not only in the subject of botany).
More knowledge was gathered by the numerous travellers. The crusades made the cause. In the second half of the 13th century, the Venetian MARCO POLO travelled through large parts of Central Asia and China and thus increased the knowledge of plants, countries, people and animals: bamboo, clove, ginger, cotton, sugar cane, indigo, rhubarb, camphor, pepper and nutmeg got to Venice. During the 14th century, monks and merchands travelled often to the Orient, but they gained only little knowledge. Partly because they had no exact powers of observation and lacked the necessary previous knowledge, partly because the travels were often badly prepared.