The species concept is a subject of eternal discussion. My experience with very narrow species concepts held by some botanists, especially, but by no means exclusively, in China, prompts me to express my opinion, especially because in taxa with which I am familiar myself some other botanists, without studying the whole genus or family at least throughout its entire Old World area, hold a very narrow, and in my opinion unrealistic, species concept. A botanist should always keep two things in mind: (1) that he or she deals with populations that form biological species, and are likely to be variable, not only within populations of free interbreeding individuals, but even more between populations with possibly varying ecological amplitudes; and (2) that his or her work, while it may reflect the natural variability in the descriptions and notes, and sometimes through the recognition of subordinate taxa, has to be used by field botanists and plant taxonomists. It must be possible for the vast majority of newly found collections to be identified by means of the provided keys not only by the specialist but also by other people. Now, what is a species? The biological species concept implies that it consists of all populations of which the individuals are capable of interbreeding. A good example is Homo sapiens. The populations are spred over nearly the entire world and differ in a multitude of characters. Nevertheless, nobody nowadays doubts that Homo sapiens constitutes one species. It is easy to find parallel examples in plants, for which several botanists will argue: populations that are so different and live so far apart must belong to different species. Of course, it is difficult to prove that individuals of different populations are interfertile. It is always necessary to study as many collections as possible from numerous herbaria, not only for a restricted area but for the whole area where a taxon may occur. I know of botanists, working for a Flora, who did not even care to consult an important herbarium, holding many collections of their taxa, in their own city of residence. It may be evident that, scientifically, I do not consider this to be good practice, and the result might well be an unrealistically narrow species concept. The narrow species concept held by many botanists in the 19th and in the first half of the 20th century was often due to the fact that only few collections were available to them, so that they could not adequately study the variability of the species. Also, some were convinced that many species were endemic in a certain area (e.g. the Philippines: Merrill) and could not be found elsewhere. It is an established fact however that some species are wide-spread and may even have a world-wide distribution, like Carex echinata Murray and Carex curta Gooden. A worldwide distribution is not an exclusive privilege of mankind! Earlier botanists would have adopted a much wider species concept, had they had at their disposal as many collections as we presently have (or can have).