|BOTANICAL ELECTRONIC NEWS|
|No. 291 June 14, email@example.com||Victoria, B.C.|
[Dr. William A. Weber sent me this unpublished paper by Áskell Löve, presented in 1953 at the Symposium on Linnaeus commemorating the Bicentennial of the publication of Species Plantarum. The Symposium on Linnaeus was sponsored by the American Society of Plant Taxonomists and the Botanical Society of America meeting at Madison, Wisconsin. (See Weber, W.A. 1995. A bibliography of the published works of Áskell Löve, 1916-1994. Acta Botanica Islandica 12: 6-33.) I hope that BEN readers will enjoy reading this essay, in spite of its length and the fact that it was written almost 50 years ago. - A. Ceska]
Linnaeus and the Swedish Flora
The common man's hobby often becomes the uncommon man's sole interest. For centuries, the man in the street in Sweden has been a lover and student of plant life. His children and his children's children profited by-and extended-his floristic knowledge. And so it is not surprising that, out of the ranks of the common folk of Sweden, came the earliest botanists, some of them recognized throughout the world as not only the first in time but also the first in rank. Their prominence is but the natural outgrowth of the nation's interest-a folk interest-in the field of botany.
It has often been said that Linnaeus must have been the creator of the Swedish interest in plant life, since he published the first scientific flora of his country as early as 1745. But actually this was by no means the first scientific account of the plants of Sweden. Almost a century before the birth of Linnaeus, Swedish vegetation was investigated by real botanists, still unforgotten scientists like Frankenius, Tillands, Måsson, the two Rudbecks, Palmberg, Linder, Bromelius, Celsius, and others, produced manuals good enough to infect the Swedish people with an interest in plants where, even then, every garden in this long country was a bit of Paradise to its owner. Even then, two hundred and fifty years ago, the Swedish landscape in all its variations, had already become the Garden of Eden to all who needed rest from the pressure of daily work.
It was into this environment that Carl Linnaeus was born. His father was a minister who loved plants and had studied natural science in Sweden and Holland, and who brought up his son in one of the most beautiful parts of Sweden in a garden that boasted many of the prettiest flowers known in his country at that time. It is only natural that the boy was influenced by his father's interest and the general Swedish attitude toward nature, and there is no doubt that it was this combination of fortunate circumstances that gave direction to his systematic genius and artistic talents.
Certainly, Linnaeus must be regarded not as the cause but the effect of the Swedish interest in nature study, for that interest was there long before he was born. But just as certainly, Linnaeus must be credited with augmenting that interest, raising it from the unorganized to the scientific plane, where it has stayed ever since. Linnaeus did not create his people's interest, but he extended it, and its development was continued from his day to ours.
It was not long after his birth in the spring of 1707 that Linnaeus was introduced to the Swedish flora, and every summer thereafter, the father let the little lad help in the garden. Linnaeus recalled excursions that took place when he was only four years old, the boy following his father and listening to him talk about the plants they saw. Later, when he had learned to read, he used several Swedish books to help him name the plants, but it was not until he went to high school that he came into contact with the botanical masterpieces. However, as soon as he had learned to read Latin, his father gave him Aristotle's Historia Animalium, and it is obvious from his own works that these systematic writings of the great Greek were strongly influential in developing the taxonomic genius of Linnaeus himself.
This is no place to find out when and how Linnaeus began to perform studies on his own revolutionary system, and others have written books about his travels and studies all over Sweden. However, it is of some interest to state that, although he lived most of his life in Uppsala and gained academic glory there and in Holland, he studied at Lund during his first academic year and received his first influences from outside his home province in Scania, the queen of Swedish lands, where the southern climate makes the flora and vegetation more luxuriant and more polymorphic than in any other part of Sweden. Here the 20-year-old Linnaeus walked in Nature studying the beech forests near Lund, the salt marshes and grasslands at Malmö and Lomma, the heath at Billebjär, and the friendly forests at Fågelsång, to mention the names of places admired by botanists ever since.
It is possible that Linnaeus has already begun to think over a new botanical system before he came to Lund, and it is very likely that he had already become aware of the many classificatory difficulties which faced all botanists knowing a few hundred species of plants. He did not, however, reveal any such ideas in his first written book, Spolia Botanica, which he wrote about his botanical experience when he came to Uppsala at the age of 21. Three years later, however, he had evidently begun to work on his own system, since he said in a dissertation he wrote for the young John Olof Rudbeck about "De sceptro-carolino" (Pedicularis sceptrum-carolinum), that "according to the Linnean system", this plant should be classified as belonging to the division Tetrandria of the class Bidynamia. Four years later, when he was only 28 years old and had studied the Swedish flora from Lappland in the north to Scania in the south, he published the first of his many revolutionary books - Systema Naturae, which made him at once world-known and placed him together with the greatest of all great botanists of all times.
Before Linnaeus came to Uppsala he had made several small excursions in Småland and Scania, and during his first years in Uppsala he traveled a good deal around the city. However, his first great excursion to places almost unknown to other people was the one to Lappland in the summer of 1732. He then traveled on behalf of the Scientific Society of Uppsala, planning not only to "search all the three kingdoms of nature" but also to make thorough studies of the life of the natives mainly from the medical point of view. During this trip through northern Scandinavia all the way over the mountains to the Arctic Sea of Norway, Linnaeus passed through most of the several vegetational regions of northern and central Sweden and observed and studied a great number of plants never before seen by a botanically trained eye. Iter Lapponicum cannot be described; it has to be read, and read slowly, but during this great excursion the young Linnaeus came to know many of the most interesting parts of his country and touched upon many of the problems the botanists still have to struggle with in Scandinavia. Without going into detail it can be stated that Linnaeus listed a good many of the plants we now know from Lappland, and the lists were based on his own new sexual system.
The next two years were used for travels in Dalecarlia and the mining districts of central Sweden, but although he was away from home for a few years, he was constantly occupied with writing about the plants he knew there. He was certainly not old when he began to write the first drafts of his general and classical works, and it is not unlikely that on his travels in the Lappish mountains, his mind was often occupied with thoughts about Systema Naturae, Fundamenta Botanica, Genera Plantarum, Philosophia Botanica, and Species Plantarum, though finding time as well for speculations on the new Flora Suecica.
In the year 1745 Linnaeus regarded the time ripe for the publication of the new Swedish flora. He then knew about 1,140 species of Swedish plants, 866 of them higher plants, and the descriptions clearly show that he saw them all in nature, studied them carefully in his herbarium, and listened to what the people in the country had to say about the practical and medicinal value of each. This is like a modern flora but without the binary nomenclature and with many of the ideas and faults of the pre-Linnean authors. But without a doubt it was the very best flora of any country published up to that time.
Linnaeus himself did not regard the Swedish flora as a completed work, and although he used the next few years for publications of a more general character, he traveled around a good deal, studying all the provinces more intensely. He was in Öland and Gotland, those rather isolated islands in the Baltic Sea with a curious, prairie-like flora, and one summer was spent in Vestrogothia with its various types of forests and grasslands. And at last, in the summer of 1749, he returned to Scania, where he had made his first scientific investigations outside his home province 22 years earlier. The Iter Scanicum was published in 1751, two years before the great Species Plantarum. It was a great traveler's greatest contribution to the study of the natural and cultural conditions in the most friendly province of a beautiful country, and at the same time the product of the observations of a man who thought more systematically about the life around him than any other had done before.
Two years after the Species Plantarum had been published, Linnaeus had rewritten the Swedish Flora entirely. This time he knew about a hundred more species of higher plants, and now he not only arranged the material according to his sexual system but also used binary nomenclature with descriptions, which were always more elaborate and precise than those we are so familiar with from Species Plantarum. Every page bears witness that here speaks a man who knows every plant he lists, has studied it carefully and for a long time in nature and the herbarium, and has tried to unveil its developmental history and secrets. The short descriptions borrowed from other books for the Species Plantarum are absent in the Swedish Flora; in fact, this is the only floristic work of the great Linnaeus which completely avoids reports unsupported by the direct observations of the author himself.
When Linnaeus published Species Plantarum just 200 years ago, he knew about 6,000 species of plants from all over the world. We now know about 270,000 species of higher plants, or almost 50 times as many taxa as he knew. It is, therefore, understandable that many of the foreign species known to him only through descriptions or drawings or, at best, herbarium specimens, must be regarded as collective and preliminary, and it is often apparent that Linnaeus himself was quite aware of the shortcomings of this fundamental book. Not so with the Swedish Flora. Here was Linnaeus at his very best in every respect. The descriptions are exact and definitive, and the species delimitations and the generic as well as varietal criteria follow the definitions of the different taxa which he regarded as useful, although this could not always be maintained for material from other regions. Is it not just what is expected from a botanist who knew only about two per cent of all plants but more than fifty per cent of the flora of his own country, that his treatment of this flora should show all his real principles of classification many times better than his books on plants he knew so much less about?
It is possible to study the Linnaean reaction to several of our present problems by aid of the later edition of his Swedish Flora, as many of the main riddles that different branches of botany still have trouble with are also met with in the flora he knew better than any. A geobotanist would certainly find a high number of interesting examples where Linnaeus distinguished between ecologically or geographically different taxa on the basis of their geobotanical characteristics. A morphologist has a gold mine of data in the Swedish Flora, and a botanically minded medical or pharmaceutical man finds here plenty of interesting observations.
However interesting it would be to touch the subject from all these angles, I suppose it will be most appropriate for a Swedish-educated cytogeneticist with strong affiliations with taxonomy to concentrate upon observations of how our great old Linnaeus treated cases we now think we understand through our knowledge of cytogenetic phenomena. It is not necessary to take note of his generic concept as compared with our present-day knowledge of basic numbers of chromosomes and chromosome morphology, although it is worth while here to point out that his thesis: "Confusion in genera means confusion in everything" will be accepted without hesitation by all modern "splitters" and experimental taxonomists. Linnaeus knew his Swedish flora intimately, but it should be kept in mind that no genera are endemic to Sweden, and that he was aware of the fact that the limits of a genus cannot be drawn until all its species are thoroughly known.
One of the most discussed taxonomic problems of this century is the one connected with apomixis. Even before this type of asexual seed formation was discovered, some taxonomists had begun to split some genera into a large number of "microspecies", each with a definite but small area of distribution and usually characterized by a single small, though very constant, character. Within the genera Taraxacum, Hieracium, and Rubus, the microspecies thus described already number several thousands, and also within other genera microspecies of the same kind are known. As the lack of sexuality within these apomictic groups makes it impractical to define species on the basis of reproductive characters, several recent botanists are inclined to regard the descriptions of these microspecies as unproductive or unnecessary work, while others have pointed out the value of, for instance, many of the microspecies of Taraxacum and Alchemilla for studies on distribution and evolutionary history of floras. Linnaeus was an extreme "lumper" where the apomictic genera in Sweden are concerned, since he recognized only the collective species Ranunculus auricomus for all the microspecies of that complex; his species Rubus fruticosus included the hundreds of microspecies and hybrids now listed in the floras, and Alchemilla vulgaris is the Linnaean name for than more than 20 microspecies known from this country. The more than 500 Swedish microspecies of Taraxacum, known from different parts of the country, many of them common where Linnaeus himself collected and traveled, were all named as the collective species Leontodon taraxacum, and the more than 2,000 microspecies of Hieracium hitherto described from Scandinavia are included under only eight species names. Therefore, the modern splitters of the apomictic genera do not get any support from Linnaeus, but he also seems to be too conservative for today's most conservative lumpers of these groups.
Another phenomenon much discussed by recent botanists, especially in North America, is that of the occurrence of hybrid swarms between species with the same number of chromosomes but differing at least in morphology and ecology. There are some difficulties in defining the concept of hybrid swarms in some instances, but at least one may say that these swarms may run almost without interruption from extreme cases which show no hybrid sterility at all, to species with an almost complete sterility barrier. In the latter, the occasional mixing of genes is usually thought to be the cause of so-called introgression. Linnaeus was well aware of some of the still-discussed instances of hybrid swarms and introgression, and his treatment differed in different cases, just like that of present-day botanists. A few examples will demonstrate this.
According to one of our most outstanding botanists, the great variability of almost all the characteristics of the two common species of Typha (cat-tails) on the North American continent might be caused by introgression. Linnaeus was lucky enough to study these two species in Sweden, where the broad-leaved T. latifolia is always broad- leaved and has the male and female parts of the spike close together, and where the narrow-leaved T. angustifolia is always narrow-leaved, with distinct space between male and female parts of the spikes. Linnaeus certainly studied the completely sterile hybrids between these species in different places, among them Lomma near Lund, where students are still able to observe them. As no fertile intermediates are seen there, he did not need to speculate on the possibility of introgression. I am not quite sure that he would have been as certain of his two species if he had traveled through the American continent, although I think we do not yet completely understand the variability of these species here.
Another complex much discussed by botanists and well known by Linnaeus is the dioecious species of Melandrium, which is usually included in the genus Lychnis by American botanists. There are two taxa of dioecious Melandrium in Sweden, a red-flowered one with comparatively small flowers and hairy green leaves, growing in forests, and a white-flowered one with big flowers and short-haired bluish-green leaves, growing in open fields. Since they are morphologically and ecologically very distinct and even known to occupy different geographical regions, it is generally agreed by most taxonomists that these two taxa should be kept as separate species. Experimental taxonomists have pointed out, however, that wherever the white- and red-flowered taxa meet, they hybridize freely, and because the hybrids do not reveal any decrease in fertility, they give rise to a real mixture of fully vital types which show all possible combinations of the many characteristics of the parent taxa. As an example of how far this can go, it can be pointed out that at least the great majority of the populations naturalized in North America seem to be the result of hybridization so that, for instance, the white-flowered type pictured in Britton & Brown, Illustrated Flora, is clearly a hybrid offspring. Experimental taxonomists regard it as most appropriate to classify the dioecious Melandrium only as two races of the same species, and in this they are supported by Linnaeus, whom treated them as two varieties of the species Lychnis dioica.
It is always easier to formulate the rule than to follow it consistently. So, although Linnaeus tried to delimit species by aid of inherent characters only, and accepted as the fundamental character of species their hybrid sterility or incompatibility - or, as Ray had already put it, that the species should be characterized by a distinct propagation from seeds (distincta propagatio ex semine) - he did not always reach the same conclusion as our present-day experimentalists. The examples noted above reveal some part of his inconsistency as to the hybrid swarms; here, as well as in the treatment of the apomicts he was usually a lumper, although his principles were those of the splitter. However, in one group of phenomena Linnaeus was almost always a typical splitter and agreed in detail with modern experimental treatments. I am thinking of his understanding of so-called intraspecific polyploids.
It has been claimed by cytologists and plant geographers having some cytological interest that, in a great number of what they call the "Linnaean species", more than one chromosome number characterizes each entity or, in other words, this so-called "intraspecific polyploidy" should be regarded as a fairly common phenomenon. Some of the scientists claiming the occurrence of such intraspecific "races" have agreed with Dr. Turesson, the Swedish founder of the genecological branch of experimental taxonomy, when he stated that "the idea that a species in the Linnaean sense should be characterized by a definite and specific chromosome number has been given up." It has to be kept in mind, however, that at least the great majority of those who have published reports on "intraspecific polyploidy" have either been quite ignorant of taxonomy or so interested in other things that they did not regard it necessary to check their material by aid of books other than semipopular manuals. Although manuals of floras far from Sweden tend to identify their species with the Linnaean taxa "in their typical sense", it is not always certain that Linnaeus himself would have agreed; and even in Sweden there are in use manuals which lump together Linnaean species under one Linnaean name only. Personally, I am of the opinion hat the only species which should be regarded as typical for the species concept of Linnaeus should be those thoroughly known by him, and not his clearly collective ones. I am also quite convinced that he would have joined issue with most of the foreign lumpers who make some of his good species so wide that they can also include related types from faraway countries. It is, no doubt, convenient for many, but it is bad taxonomy, and Linnaeus was a very good and careful taxonomist.
During the last fifteen years I have had the opportunity to scrutinize all reported instances of so-called "intraspecific polyploidy" within the Scandinavian flora. If all the reports are included, as many as seven per cent of the species met with in this region should include types differing in the chromosome number but morphologically so closely related that the observer in question-usually not a taxonomist-does not regard the differences of any value for their taxonomic separation. It is unnecessary here to mention examples where the differences are known to occur on different continents or in regions as remote and unlike as Scandinavia and Spain or Japan, especially inasmuch as Linnaeus himself did not know the foreign material. Taking Swedish plants alone, over 90 per cent of which have been cytologically investigated, we find reports published on the occurrence of more than one chromosome number within morphologically inseparable types of several genera growing within this region. But my studies of these so-called "intraspecific polyploids" of Swedish plants has convinced me that the claim that this occurs within inseparable types of Linnaean species is false. Linnaeus himself almost always described the taxa in question as different species, although later authors of manuals did not recognize them as such. It cannot be his fault that we are not always as good taxonomists as he was himself. We can take a few examples to demonstrate his treatment.
Several papers have been written by cytologists and agronomists about the intraspecific polyploidy within the genus Phleum (timothy). Some of these scientists claim that the species Phleum pratense, of course in the Linnean sense, should include two diploid "races", one tetraploid "variety" and one hexaploid taxon, while other lumpers regard it as more convenient to divide into two so-called Linnaean species, P.pratense including a diploid and a hexaploid race, and P. alpinum with a diploid and a tetraploid subspecies or variety. As a matter of fact, Linnaeus himself knew only three of these taxa, and he did not hesitate to classify them all as different species. In the really Linnaean sense, the diploid timothy is the species P. nodosum, while the hexaploid timothy is typical P. pratense.
As to the species named by him as P. alpinum, he included in it material from Scandinavia known by him from nature, as well as specimens from the Alps described by others. Long before cytology became a science, a good Linnaean taxonomist in the Alps observed that in Switzerland there are two different closely related species of this group. He regarded one of them as identical with Linnaeus' P. alpinum, but described the other as a new species, P. commutatum. Later on, it was shown that, while the former is a diploid endemic to the mountains of central Europe, the latter is a circumpolar tetraploid. It might seem to be unfortunate that the Linnaean species name as retained after the division is the one with the smaller area of distribution and not found in Sweden, but as this change was quite according to the Code of Nomenclature, it has been accepted for a long time all over Europe. Still, it seems to be unknown to North American botanists, at least those who have written our most recent and most frequently used manuals.
Another case is with regard to the collective species, Agrostis alba. Here, intraspecific polyploidy has been reported several times from different countries. It has been claimed to include tetraploids with 2n=28 chromosomes as well as hexaploids with 2n=42 chromosomes outside as well as inside Sweden. There is no doubt that the tetraploids are identical with the species A. stolonifera as Linnaeus understood it, and it also seems evident that the hexaploids are identical with the typical A. alba in the Linnaean sense. Some technical difficulties as well as the great confusion in the use of the latter name have, however, forced Scandinavian botanists to reject the name A. alba and replace it with the younger name A. gigantea. But this confusion was not Linnaeus' fault as it was caused by events he himself could not prevent. The fact remains that he did consider the two polyploids two different species.
Still another case is that of the genus Cochlearia. It has almost become a practice when speaking about the northern representatives of this genus to report them all under the name of C. officinalis, at the same time referring to Linnaeus as its author. This is, of course, contrary to what Linnaeus himself did, since he recognized four northern species, C. officinalis, C. danica, C. anglica, and C. groenlandica. It is now known that these types are not only characterized by four different chromosome numbers, but they also belong to two separate groups from the evolutionary standpoint, differing in the basic number of chromosomes as well. Typical C. officinalis in the Linnaean sense is a tetraploid with 2n=24 chromosomes, and C. anglica is an octoploid with 2n=48 chromosomes, both having the basic number x = 6, while C. groenlandica is diploid with 2n= 14, and C. danica a hexaploid with 2n=42, based on the basic number 2n=14. If later botanists had followed Linnaeus more closely they would never have confused themselves so much as to lump together different sections of a genus under one extremely collective name.
Although many more examples could be given in order to demonstrate how uniform was Linnaeus' reaction to variations we now know are caused by the occurrence of polyploidy, only one more illustration will suffice. In all modern Swedish floras the species Veronica longifolia is taken in a wide sense, including as a variety the taxon Linnaeus named as the species V. maritima. From the cytological point of view these types differ in the degree of polyploidy, since the typical Linnaean V. longifolia is a tetraploid with 2n=68 chromosomes, while the other Linnaean species is a diploid with 2n=34. In this case as in many other similar examples Linnaeus was able to see specific differences where later botanists failed to understand them. And in all of these instances the correct splitting into genetically distinct groups performed by the great Swedish genius was later forgotten by the less wise lumpers, who produced confusion where Linnaeus had been able to make order.
Two hundred years have elapsed since the life of the great Swedish genius reached its peak, two hundred years rich in cultural and political changes. Thrones have risen and fallen, empires have been founded and split up again, and the industrial revolution has brought prosperity to all corners of the world. Some of these revolutions have been indirectly caused by the greatest of all revolutions in natural science, when Linnaeus alone brought order out of chaos and opened the door for the immense evolution of all our sciences. He understood pretty well that his contribution to science was greater than anything done earlier, and he would have been pleased if he could sit among us and state that his works are still among the very best ever written in botany. Most of us will be forgotten, but when millions of great learned and world-known authorities have become only small names on he pages of history, the name of the greatest of all Swedes will still be known to everyone interested in science. And as long as the botanical science continues to thrive and there is anyone left who cares for and admires plants, there will be many voices to join in with the students, who two hundred years ago returned to Uppsala from a good excursion with their great master and shouted "Vivat Linnaeus!"
Doris Löve wrote - but never published - a great treatment of the flora and vegetation of Mt. Washington (New Hampshire, USA).This is a monumental work. The manuscript has about 400 typewritten pages and numerous illustrations. In the taxonomical section, Doris Löve discussed 170 species of alpine vascular plants with numerous interesting notes on their taxonomy, cytotaxonomy and nomenclature. This work deserves to be published and we are looking for a publisher who would be willing to undertake this task. If you know where to go and whom to contact, please, get in touch with me at firstname.lastname@example.org and with Dr. Bill Weber at email@example.com .