A Digression on Taxonomy II

So, Linnaeus divided his world in his first edition of the Systema Naturae (1735) into three kingdoms: animal, plant and mineral, and then further divided the plant kingdom into 24 classes according to sexual characteristics. He didn't do this, however, in a vacuum. Before his time were many efforts to classify plants, but by the time of the 18th century these systems were overwhelmed by the sheer mass of newly-discovered or reported-on species. A few historical words will help place Linnaeus in his context.

The first great classifier of plants in the Western world was Aristotle's student Theophrastus. About 2300 years ago he divided the plant world into four categories: trees, bushes, shrubs and herbs. He then divided these further based on leaf shape, life span and place they grew. There were about 480 named plants in his system. The major systematizer of plants from antiquity was Dioscorides, from the first century CE, who based his classification system on utility to humans. Thus his groups included aromatic plants, edible plants and medicinal plants. Not a bad system, really, and it was widely regarded until the period of the Renaissance.

The 16th-17th centuries saw a "blessed rage for order," as scholars tried to categorize and classify the thousands of new plants discovered or reported through European conquest of most of the world. In addition to the "problem" created by the discovery of more plants, the focus of investigators/taxonomists began to change from the "human-centered" understanding of plants to an appreciation of them in their own right. This was, you might say, the horticultural equivalent of Copernicus' 16th century work on the planetary system.

Linnaeus' sexual system would not ultimately win the day; rather it was an Aristotelian concept (the type concept, which maintained that species are non-varying and fixed entities) that would eventually become the basis of the classificatory system of our day. We would arrange things according to "natural type" rather than by "sexual characteristics."

Before looking at Linnaeus' system briefly, we ought to pause for a moment. The point of pausing is to consider that it has taken us more than 2000 years just to classify the stationary living things around us, and a good argument could be made that with the advent of emphasis on very small, microscopic entities, we are still in the initial stages of proper classifications. Deciding on the proper categorization of the plants of the world has been the biggest headache. How, indeed, should you put things in categories/organize them? We teach as if the Linnaean classification system (not the sexual system but the terminology of genus and species) was the most natural thing in the world. But it wasn't for most of our history; utility of plants for human betterment was the system. We also still lump all kinds of things in the same category which certainly will find their own homes some day, such as the many many species all grouped under the category "Philodendron." The variety of the world is a challenge to all of us who think that we have the "right categories" by which to explain the world. New ways of looking not simply at the plant world but at every intellectual creation are invited by our experience with the plant world. Thus, criticize plant systematics; criticize any attempt to impose order on a phenomenon. Do a better job. Certainly, the systematizers, like Jesus' poor, will always be with us. I am one of them, I fear. But we should realize the impossible nature of our task from the outset and be humble about it.

Finally to Linnaeus

Here are the 24 categories or classes into which Linnaeus divided the plant kingdom:

* Classis 1. MONANDRIA
* Classis 2. DIANDRIA
* Classis 3. TRIANDRIA
* Classis 4. TETRANDRIA
* Classis 5. PENTANDRIA
* Classis 6. HEXANDRIA
* Classis 7. HEPTANDRIA
* Classis 8. OCTANDRIA
* Classis 9. ENNEANDRIA
* Classis 10. DECANDRIA
* Classis 11. DODECANDRIA
* Classis 12. ICOSANDRIA
* Classis 13. POLYANDRIA
* Classis 14. DIDYNAMIA
* Classis 15. TETRADYNAMIA
* Classis 16. MONADELPHIA
* Classis 17. DIADELPHIA
* Classis 18. POLYADELPHIA
* Classis 19. SYNGENESIA
* Classis 20. GYNANDRIA
* Classis 21. MONOECIA
* Classis 22. DIOECIA
* Classis 23. POLYGAMIA
* Classis 24. CRYPTOGAMIA

Take for example the Decandria, Classis 10. It consisted of flowers that had ten stamens. Within that class were various orders, one of which was the Decandria Trigynia, which were flowers consisting of ten stames and three styles. Take the Didynamia, Classis 14. This class consisted of flowers with four stamens, arranged in pairs (didymos is the Greek word for pair): the outer pair being longer than the inner pair. Classis 16, the Monadelphia, was a class having the stamens united into a tube, or ring, by the filaments, as in the Mallow family. This page has a brief description of what each of these 24 Classes contained.

The 24th, or the Cryptogamia, were described as follows: "Plants without proper flowers." Or, in other words, plants in which it wasn't possible to discern the sexual organs. Before turning to a description of these, it would be helpful to note that Linnaeus' system, with some notable exceptions, won fairly instant commendation because it was very easy to understand and, thereby, to classify things in proper categories. However, in 1789, the Frenchman A.L de Jussieu, in Genera plantarum, first explored a "natural" system of classification, which is now the basis of our work.

What was this 24th Classis? The next essay brings us into the "secret marriage" category.

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