What is the PURPOSE of plant taxonomy?

In the late 1970s, I wrote an essay for a course I was studying towards my degree in botany at the University of Southampton, entitled, TAXONOMY PROVIDES A BIOLOGICAL INFORMATION SERVICE.  EXPLAIN.  By reproducing the essay below, it shows that even as a humble undergraduate, with limited actual experience, I was aware of important and pertinent issues which remain relevant to this day! 

"To the educated observer, the suggestion that providing a biological information service is not a major objective for taxonomists would seem strange.  This, however, was most definitely the case.  Heywood (1975) states, 'that until recently, my suggestion that information processing was a major role of taxonomy was vigorously repudiated as being a pursuit unworthy of scientists in this evolutionary age'.  Any essay on a topic such as this must therefore concentrate on why taxonomy does not provide an adequate service and what is being done to rectify the matter.

This account will be to a large extent based upon a summary of the past and present undertakings in taxonomy given by Professor V.H. Heywood, at the Proceedings of the 8th International Conference on Numerical Taxonomy.  For once we should begin this appraisal with confidence and enthusiasm, if such an admirable account can be given by one of the world leaders in the field of 'traditional' taxonomy, then the way forward seems to have been shown. His viewpoint is botanically biased for obvious reasons; the same will be said of this work. For this, no excuses are to be made, as it allows the author to give a much more competent assessment of the situation due to his greater knowledge of botanical taxonomy.  It also prevents a drawn-out explanation of the differences on the zoological side, which would not benefit the explanation.

Before considering why taxonomy should be like it is today, a brief mention of what exactly is the function of the taxonomist at the present time would be valuable.  It is easy enough to list the main approaches or philosophies professed today, whether they be phenetic, phylogenetic, cladististic or evoloutionary.  This does not as one might suppose, indicate how the majority of taxonomists are occupied, although it may correspond largely to the beliefs of the academic sector of the community.

Given that a survey were made, it would discover that most professional taxonomists do not spend much time philosophising about which approach to adopt.  They like any other professionals have a set of procedures, certain materials and basic equipment to utilise, following a more of less largely Internationally accepted set of conventions.  With these they produce floras, faunas, monographs, provide an identification service etc.

A most peculiar position exists.  Every taxonomist seems to be expected to belong to one school whose beliefs should give different results to those achieved by a taxonomist from another, even when using the same basic materials.  Some may suggest that differences in classification produced by a particular researcher are due to adherence to say, cladistics versus a phenetic  viewpoint or philosophy.  What is really the reason can be attributed to such variables as the data-base (by 2016 I am more than aware than most data-bases are unreliable - full records where species supposedly observed have often been misidentified, which applies both to Himalayan and British flora records); differences in experience; time devoted to the problem or adoption of narrower or wider taxon concepts - which may have little to do with evolutionary or phylogenetic considerations. What this means is that human, non-scientific influences still play a large part in the workings of taxonomy.

This can be well-illustrated by the many instances of increasingly precise techniques, especially numerical or taxonomic that are applied to impressively defused situations and variables with inadequate samplings of material.  A conspicuous contrast has developed between the lack of precision and extent of subjectiveness adopted in selection, handling and arrangement of data to produce a classification and the scientific exactness with which these data may have been procured.  This contrast is a very important one, which points to the need for improvements in some aspects of taxonomy.

To fully understand what service taxonomy does provide at the present time, one needs to investigate the characteristics of pre-scientific classifications of early man from which modern taxonomies have developed during the cultural evolution of Homo sapiens.   Work on folk taxonomists (notably Raven) used by the few remaining tribal societies have many characteristics in common.  They have a much more restricted hierarchy, with overlapping occurring.  The number of taxa is relatively speaking, small.  This constraint is due to the verbal nature of their taxonomies, which necessitates that the members in the tribe know the characteristics of a particular taxon. (I have some understanding of how things were in the past, due to my long-standing interest in Himalayan species utilised in Tibetan Medicine; the doctors of traditional medicine used their own names/taxonomy - tallying them with our Latin plant names is no easy matter, as often more than one species (according to western methods of naming plants), sometimes more than one genus and at times, more than one family (using the precise botanical meaning of the word) are collected under a single Tibetan name!  These doctors of traditional medicine refer to medieval texts as reference works/floras).

Scientific (so-called) taxonomy developed in well-off European countries during the 18th and 19th centuries against a set of assumptions stemming from folk taxonomy, which are obviously very different from those in use today.  Linnaean taxonomy was non-evolutionary and static, being largely Aristotolian in philosophy.  The dimensions envisaged at the time were significant, with an implicit assumption that the number of organisms to be dealt with would perhaps be 25-50,000 not somewhere in the region of 10 million as is estimated today.

It is worth noting that had Linnaeus realised the real scope of his undertakings in producing a classification, he would almost certainly not have attempted it!  Also, credit should be given to the taxonomists of the time, who clearly worked with great energy and perseverance to produce remarkable results.  Could they have been expected to do better under the circumstances?  (Having now some grasp of the heroic efforts of Hooker and his co-authors towards 'Flora of British India', I am greatly impressed that so much was achieved, often with scanty and poor quality specimens - India owes him a great debt as does Pakistan to the 'Father of Pakistan Botany', Dr R R Stewart, who is credited on this web-site).

Genera Plantarum (1737), contained less than one thousand genera (this being the basic taxonomic unit), which was the codification of the local taxonomies of Western Europe with which Linnaeus was familiar.  The information content was poor but a start had been made to the advance towards a satisfactory classification.

The post-Linnaean period saw an information explosion in taxonomy.  Exploration and exploitation of overseas territories by European, Imperial and Colonial powers caused an enormous influx of material.  This formed the basis of the great Systematic Collections, many of which still exist today, in the museums and herbaria of Europe (such as the Royal Botanic Garden, Kew and the Natural History Museum in London).  Associated with these came the opening of many Botanic Gardens to act as centres of the spread of new plants for agricultural and commercial as well as ornamental utilisation.  A lot of time was devoted to floras and faunas, descriptive catalogues and lists, volumes of illustrations and accounts of exploration of new territories, as any trip to a well-stocked Biological Library will testify.  Thus taxonomy had changed, becoming a system of communicating about the unknown to other people, though at the time, the significance of this was not realised.

No longer did the names of the taxa always indicate their properties, the vast numbers involved precluded knowledge of all but a few in any great detail.  Most workers did not know all the characteristics of the higher families and Orders, let alone lower taxa.  Taxonomy had supposedly become a highly specific information science and yet little serious attempt was made to consider its efficiency.

It clearly was not an efficient system, however impressive the volumes produced appeared, only a confined proportion of taxa had been discovered, with a notably small part of the data obtainable being utilized.  There was no general system for upgrading information except possibly the museum or herbarium collections which are only used by a restricted set of biologists(and almost 40 years on, the situation has, in my opinion, not just NOT improved but go significantly WORSE).  The situation clearly got out of control, with the flow of material and information being too much to cope with. (And nowadays there are insufficient herbaria and botanical taxonomists, whilst field botanists who can make the collections and field observations, are a dying breed). Towards the end of the 19th and beginning of the 20th centuries the works of two men revolutionised biology: Darwin and Mendel.  Attention was focussed on phylogenetic and evolutionary relationships as explanations of the diversity of nature.  Quite possibly their discoveries had a harmful effect on the practice of taxonomy, certainly taxonomy was retarded as an information service.

Numerous problems have been, and still are being caused by the failure to understand the study of evolution and evolutionary mechanisms can be separated to a sufficient extent from the study of the principles and methodology of constructing classifications.

The 'New Systematics' of the 1930s and 1940s opened up yet another new era in taxonomy.  Discoveries made in genetics, cytogenetics, cytology, population studies and statistics produced hopes of replacement of the 'subjective' statistics produced by an 'objective', scientifically and workably defined 'biological' or 'genetical' species concept.  This has not come to fruition.  Raven (1974) observed. 'Perhaps the most important discovery of the past 25 years, is that biosystematics studies do not lead to an unequivocal definition of the taxonomic units in most groups'.

As a result of the application of technology to systematics over the period just mentioned, there has been am almost explosive increase in information becoming available to the taxonomist.  This largely comes in the form of biochemical or molecular data plus the increasingly widespread use of the scanning electron microscope.  If is customary to divide chemosystematics into micro-molecular, dealing with monomeric compounds e.g flavonoids, alkaloids and terpenoides.  The other vision is macro-molecular, the polymeric compounds: proteins, nucleic acids etc.  These differences are reinforced by instrumentation and techniques used.

Whilst some works in this field have yielded highly significant information namely Alston & Turner's hybridisation studies of Baptisia, Sibley's survey of electrophoretic patterns of egg white proteins in Passerine birds, Mabry et al, their survey and interpretation of the distribution of betulain and anthocyanin containing families in the Centrospermae or Boulter et al, reconstructing angiosperm phylogeny from amino acid sequence data in cytochrome C and plastocyanins - using numerical cladistics methods.  The majority are just surveys of particular compounds (especially in the plant kingdom).  Journals and articles abound with this data but what is being done with it?  The need to devise methods for the treatment and coding of the information to allow its proper utilization is very real.

Now that we have reached the present day, it is time to discuss what information taxonomy does provide? Let's begin with the lowest levels (which I now consider amongst the MOST important role for taxonomy).  There has been a vast increase in the publication of field guides and other identification aids to the interested layman on everything from bryophytes to mammals. Whilst a lot are not worthy of much consideration - these have jumped on the band-wagon being compiled inaccurately by authors with minimal knowledge, some really do provide an excellent source for the general public.  Good progress has been made in familiarising the interested amateur with their surroundings.  This is of VITAL importance today when the need for consideration and good management of our resources is so apparent.  The Hamlyn Guides to the 'Birds of Britain and Europe' and 'The Seashore and Shallow Seas of Britain and Europe' plus the Collins Field Guides to 'Insects of Britain' and the 'Wildflowers of Britain and N.Europe'  provide good examples, which with the aid of helpful publishers, are of genuine value for money.  The success of the television series and the book 'Life on Earth' by R. Attenborough, show that there is genuine interest, which should spur on taxonomist to help other biologists reach more people.  (I was somewhat alarmed to discover from the late Oleg Polunin that his early guides to the Flowers of the Mediterranean and Europe, received criticism from some academic botanists/taxonomists who seemed to disapprove of a 'popular' guide for non-academics; another important consideration is that whether these guides and indeed all floras are utilised well by those who use them; it became clear to me when I began my interest in Himalayan flora, that too many people incl. scientists and even botanists who had not been taught how to identify plant correctly - please note my skills in this respect did not come from either an 'A' level biology course or even a degree in botany - seem to think they can easily and reliably identify plants by matching with pictures in a guide-book; they are mistaken; I have used 'Flowers of the Himalaya' by Polunin & Stainton more than anyone alive and have noticed how badly it is used by many others, frequently leading to misidentifications; few plant enthusiasts have ever been taught how to RELIABLY identify plants).

At a slightly or markedly higher level depending on usage, two works stand out in recent years. 'Flora Europaea' in its volumes and 'Flowering Plants of the World' (1978) present a new concept in flora writing.  The collective responsibility of editors and the willing cooperation of authors, whereby manuscripts are submitted for review by a team of advisers, in the former case representing each European country, is just what is needed.  The role of the editors is to interpret and assess, to achieve a balanced view of such topics as taxon status, treatment of critical groups etc.  Generally speaking only congratulations can be given for the undertaking and fulfilment of these works. (Unfortunately, as a financially impoverished private individual, I cannot afford to buy 'Flora Europaea' and have not consulted it personally, decades later when I am now in a position to more critically assess its usefulness).  It is perhaps a pity that in the latter volume, Professor Heywood, being consultant editor, could not have provided a better assessment of the work.  As stated in a review by Cannon, 'a forthright introductory statement to the effect that whilst some families were by experts, others were the result of honest compilation by non-specialists, would have both put the book in its true setting and won the respect of the many informed readers who will recognise 'tares' (meaning injurious corn-weed) lurking amongst the rich harvest of wheat'.

The recent trend to organise symposia on individual Angiosperm families, drawing together experts from various disciplines is clearly another encouraging improvement e.g. Cruciferae (now Brassicaceae); Umbelliferae (now Apiaceae); Compositae (now Asteraceae); Solanaceae and others.  These have highlighted that the service the taxonomist provides for the professional scientist whether plant breeder, biochemist or agriculturist is not adequate by any means.  An inability to answer even straightforward questions on distribution of chemicals for related taxa cannot be reasonable accepted.

At present no widespread, effective mechanism exists for handling of the great masses of data that have been published.  the need for computer data banks or catalogues is particularly apparent, if future efforts are not to be wasted.  A general system to record information on natural products would benefit applied as well as basic research, and remove the present time-consuming searches.  As the workshop on trends, priorities and needs in Systematic and Evolutionary Biology held at the Missouri Botanic Garden urged, 'the priority must be to build data banks where information can be readily added and retrieved' (However, since writing this essay it has become increasingly clear to me that much of the data/records submitted to the data banks which have been established in the intervening years, cannot always be relied upon; as one says, 'RUBBISH IN; RUBBISH OUT'.......  and increased concerns of EXPLOITATION OF GENETIC RESOURCES means that greater restrictions are going to be imposed upon access to and sharing of information about such resources e.g. medicinal uses of said resources in traditional medicine; this is a retrograde step)

Having to accept the role of custodians of a general biological information system, however inefficient it may be at the moment, is the task ahead.  Greater effort must be devoted to practical information storage and retrieval.  This may well lead to an overall change of emphasis in the ways in which systematics and taxonomy are run and involve a realignment of resources.  Resultant streamlining of the most academic aspects of taxonomy could easily lead to significant improvements in efficiency and quality.

For too long research has been conducted in a haphazard and pot-luck way, the need for collective planning is now.  This will mean some loss of freedom but this must be accepted in the interest of more effective deployment of a limited labour force faced with a massive work-load.  The way ahead is cear and strides have been made in the right direction.  It is not easy to alter a science with such long-standing traditions.  A visit to the herbarium at the Royal Botanic Gardens, Kew would show how impractical and drastic alteration would be, so some systems since they do work, albeit not as well as would be liked, must be accepted for what they are, for the present at least.

As a final comment, Botanical taxonomy has one overriding advantage which cannot be overemphasised, 'Botanical Latin'.  A letter to the Cambridge Review (1960) by E.J.H. Corner, seems most apt, 'We botanists keep Latin alive. We read it, we write it, type it, speak it when our mother tongues fail and succeed in putting such remarkable things as orchid flowers and microscopic fungi into universal understanding through Latin. If we didn't the Babel of tongues and scripts would close our accord, and we would be at the mercy of politics'.


Cannon, J.F.M. (1979)    Book Review.  Flowering Plants of the World. Watsonia, 12, 365-367
Griffith, G.C.D. (1973)    Systematic Philiosophies. Syst. Zool. 22:286-391
Heywood, V.H. (1975)    Proceedings 8th Int. Conf. on Num. Taxonomy.  Ed. G.F. Estabrook
Heywood, V.H. (1978)    Flowering Plants of the World.  O.U.P.
Raven, P.H. & Broadlove, D.E. (1970)    The origins of taxonomy.  Science  174: 1210-1213
Stearn, W.T. (1973)    Botanical Latin.  David & Charles
Vaughan, H.D. (1973)    Biology and Chemistry of Cruciferae
Wayne & Moss, W. (1973)    Disc. of Sympos. papers on contemporary systematic philosophies Syst  Zool  23: 394-395

To be continued.