As I was not sure if this title appeared on the
Congress program, I asked Steven Hammer prior to my departure for the
States what title was advertised for my talk. His reply was that I
should not worry as the titles for talks of this kind tend to mutate.
In relation to my jaundiced view of Haworthia literature, I thought
that this itself would make an equally good title for the subject of
the talk.
I have come to the U.S.A. on invitation and the
reasons I accepted this invitation are manifold. Primarily I feel a
sense of responsibility and duty to the subject, secondly I feel a
sense of obligation as my interest in the genus owes much to the USA
for the role J R Brown played in stimulating my interests in the
genus, and thirdly I felt I ought to dispel the discomfort of the
culture shock I had experienced in the U.S.A. when I visited it in
1982.
I have wanted to give talks that will in some way
enrich the lives of the people who hear them, and this seems to be a
very arrogant wish against the limited wisdom which an ordinary
individual can acquire about anything in a life-time. But I am
concerned about the confusions and controversy, which seems to be
associated with the plants I enjoy so much. Classifications and
taxonomy have acquired such a negative connotation, and yet they are
both fundamental to the whole experience of knowing and growing
plants. Without good classification there is no way of organising our
thoughts and communicating with one another about the plants.
My interest in Haworthia dates back to my childhood
and a deeper interest developed from plants of H. limifolia, which an
uncle had collected in Natal. Living in Natal myself, I started to
collect plants by corresponding with other collectors and nurseries.
It soon became obvious to me that most of the plants seemed to be very
ordinarily the same. I was by then a qualified entomologist
researching the biology of Noctuid moths, and my study was taking me
into the realm of classification and identification which formed the
basis of my master's thesis. My career took a turn and from a
government research post I moved to commercial agriculture until
fortuitously I landed up as Botanical Assistant to the Curator of the
Karoo Botanic Garden in Worcester. There I was given the job of
curating collections and given access to the Compton Herbarium and all
the Collected Works of G G Smith. I very quickly learned that there
was little relation between the available published works on Haworthia
and the diversity of the plants I was seeing in the field.
Six years later I could produce a book which was an
illustrated checklist of names which I thought could be used to
usefully explore the Haworthia further, and also to provide a firmer
basis of John Pilbeam's book on Haworthia and Astroloba. My handbook
was revised in 1983 and then in 1985, Col Scott's book was published
which virtually ignored anything which either Pilbeam or I had done.
This book seemed to undo any progress which had been made to stable
nomenclature in Haworthia and I was very disappointed to find my work
categorised with the confusion that collectors have since found
themselves in. My conviction is that publishers, editors, other
writers, and other collectors whether really serious or not, have
simply failed to properly identify the sources of confusion and
address them in an ordered way. In my talk I would like to deny any
responsibility for any confusion and try to acquire some credibility
by pointing out that my work is based on:
1. Extensive fieldwork and thus familiarity with
the plants in their native state
2. A knowledge and review of all the literature (I may be the last
person who can say I have read all the literature)
3. Extensive experience with pattern recognition in biological
systems
4. Knowledge and experience of classification and identification in
many plant genera
5. A very comprehensive physical herbarium record located in three
different herbaria
6. A clear species definition for the work
7. A long period of validation and testing over a period of 35 years
from my first publication on the subject, to the present
When a recent catalogue stated that there was
confusion in Haworthia classification, what they were actually doing
was confessing their own downright intellectual laziness, and
inability to discriminate between writers who are themselves confused
and those who are not.
What the actual problem is, is that plants are not
as easy to classify as we tend to believe. When I started to delve
into classification of Haworthia, I was warned that 'the ship of many
a taxonomist has been wrecked on the rocks of the Liliaceae'. The
consequence is that I have always steered a very deliberate and
careful course. G G Smith had given up writing about Haworthia in
disgust because of the acrimony he generated after criticising
Resende, Von Poellnitz and Uitewaal for their parochial views about
the genus. I did not think that he was much above criticism himself
and so this has been a strong lesson for me. Before leaving South
Africa I was reading Steven Gould's book "Ever Since Darwin".
He makes two statements which should be foremost in the minds of
collectors. The one is "The strongest statement that a student in
the biological sciences can make is 'hardly ever'". The second is
"The chimera of certainty is for politicians and preachers".
Now Darwin is interesting because it seems that
before Darwin, people were regimented into believing that creation was
the product of a divine creative event and not subject to
understanding and study. Darwin showed that creation was subject to
analysis and rational thought and could be known and understood.
Unfortunately there has also been some misconception about how this is
done. One of the myths in classification that has arisen is that there
are little boxes into which these products of evolution can be
rigidly placed. This is despite the fact that Darwin was pointing out
that living things were in a state of continuous change. The second
myth is that complexity has arisen from some simple origin and that
species in present time are considerable more diverse that they were
at some earlier point in time. The fact is we see genera which may
have several species which are fairly specialised and uniform, as
against a few others which may be highly variable.
In reading Gould's book I was also reminded of my
childhood belief that the continents of the world had once been joined
because they so obviously fitted together. It was interesting to
observe that it is only in the last ten years that this hypothesis is
accepted as a probable explanation because tectonic plate studies
provide an explanation for how this has happened. However, it is the
denial of continental drift in the absence of a prior knowledge of
this mechanism which is curious to me and I do not think that is
science. This has strengthened my view that science is not a matter of
education and qualification, profession or position and an impressive
CV. It is an attitude which is grounded on common sense and
organisation of scepticism.
In order to have this attitude about species, we do
need to have a reasonable idea of what a 'species' is. Unfortunately
science seems to have failed us here as good definition of the term
seems either hard to find or impossible to understand and we have to
go our own way to do so. Firstly we have to consider that the work
should be seen to be a postulate of the biological sciences for a
concept of a basic building block for the understanding and
classification of all living things in a unified system. Thus it is
not for us to hi-jack it, and use to classify things in our individual
minds on a basis of limited information, limited material and limited
understanding of biological systems, for our own limited purposes.
Unfortunately available definition of the term is
poor. The Collins Dictionary defines 'species' as those groups into
which a genus can be divided, and it then defines 'genus' as a group
which can be divided into species. The Websters' Dictionary inserts
the work 'logically' before 'divided'. Very few botanical revisions
and classifications actually address this question of definition,
while on the other hand there seems to be intense intellectual
discussion of a biological species concept against other concepts. I
cannot see much sense in this. Generally the zoological concept of a
species as 'a group or groups of individuals capable of interbreeding
or potentially interbreeding' is basic to the classification system.
This fails in plants because of interfertility across even generic
lines. I have simply devised my own definition as 'a group or groups
of individuals interbreeding or potentially interbreeding which vary
continuously in space and in time'. This brings us face-to-face with
the actual problem of having to determine where these continuities are
in space and in time. The problem is that it is the continuities that
are obscure and confusing and difficult to describe and circumscribe.
Knowing this can make a big difference to how we organise our
scepticism about a classification and what we should look for to
determine the credibility of writers who can do no better than to
confuse themselves and the rest of us.
All too often the view is expressed that
classification is an art form and that it expresses the opinions of
the individual. If imagination, phantasy and ignorance are the
qualifications for the work, then indeed art is what one may get.
In truth classification is and has to be a science
in the sense that it has to be based on physical and measurable data.
That data has to be accessible to all. Statements must be verifiable
and if they are contested, new data should be presented to verify the
new and proven statement. This gives rise to a structure of knowledge
and information in which the names we use are meaningful and
informative. In the case of Haworthia there is a problem (which is not
incidentally unique) in that there are very few tangible characters on
which classification can be based. Even the characters which
differentiate genera in the larger context can be disputed. Therefore,
the key to understanding species in Haworthia has to be based on
geographic distribution and the spatial relationships and continuities
which are observed in the field. Unfortunately again, the strictures
of the nomenclatural system and its controls to stabilize names, does
sometimes make it a little difficult for the classification to really
express how species are related in the field. I have recognised that
there is often continuity of varying degree between many different
species, and that often I am simply recognising significant nodes in a
fairly turbulent sea of similarity. The botanical code requires that
names may not necessarily be co-incident with principle nodes. My
approach in my first Handbook of 1976 was to try and find as great a
relationship between nomenclaturally valid names and the variation in
the field. I know I achieved this in very large measure and I have
tried to build on that foundation ever since. However, there seems to
be no way that the nomenclatural code, whatever its pretensions are to
ensuring stability, can do to prevent the structure of the
classification from being rattled, shaken and even broken. The onus
lies entirely at the door of the individual who should recognise how
important it then is for organisation of scepticism.
In my slide presentations, I have pointed out that
the genera in the tribe Aloideae of the FamilyAsphodelaceae (following
the new dispensation for the classification of plant families by
Dahlgren) are not properly understood. What hypotheses have been put
forward have been based on some very very poor character definition
and analysis. The obvious sub-divisions within the genus Haworthia
have been completely ignored and if this is the case I cannot see how
any attempt to resort the genus can have any credibility.
I have shown a 'flow-chart' showing how the species
of the 'retuse'-type species are linked in a cobweb-like diagram. I
pointed out that there are main role players in this web and that the
species can be understood in the context of names which relate to
geographic centres. My slides were selected to show some of the
pathways in and between different centres. This was also to emphasise
that a classification has to encompass all plants both known and
unknown. In this way there is a predictive element. It is new
collections and new methodology which test the classification and its
predictions. This process is how an hypothesis is tested and how a
classification is shown to be a product of a sceptical and inquiring
mind; rather than the artistic product of an individual, driven by
some undefined motive underlying a pretension to really understanding
what has been done, and what needs to be done. |