Plant Taxonomy and Nomenclature

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Methods of building a system of categorization focused more on name designation than description, making it easy to remember and study the plants.
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“The Compendium of Amazing Gardening Innovations” by Abigail Willis taps into the history of gardening through the eyes of the botanists and explorers who cultivated it.

The Compendium of Gardening Innovations (Laurence King Publishing, 2018) by Abigail Willis explores the history of gardening and the ingenious discoveries that shaped it into the productive past-time, passion, and livelihood that it is today. Willis is a qualified gardener through the Royal Horticulture Society in the UK. She writes for the London Evening Standard, the Daily Telegraph, and has authored another book called The London Garden Book A-Z. The illustrations are by Dave Hopkins whose work has appeared in numerous publications, including The Economist and Mojo. The following excerpt details the creation of classifying and categorizing plants.

Although the word ‘taxonomy’ (meaning the science of classification) was first coined in the nineteenth century, mankind has been trying to categorize the natural world since antiquity. Aristotle came up with a rudimentary system that separated the animal and plant kingdoms, and his pupil Theophrastus (‘The Father of Botany’) identified around 500 named plants, dividing them into trees, shrubs, sub-shrubs and herbs.

In the seventeenth century, John Ray developed a taxonomic system using the physical characteristics of plants as a way of determining their relationships to each other and dividing them for the first time into monocots and dicots. Ray’s Historia Plantarum, published in three volumes between 1686 and 1704, is regarded as the first textbook of modern botany and earned him the title of ‘the English Linnaeus’.

By the eighteenth century, the huge influx of newly discovered plants to the Western world was making life tricky for botanists – not least in the matter of knowing what to call them all. Latin, the universal language of learning, imposed some discipline, but with no international standard, plants acquired numerous synonyms. To add to the confusion, names included lengthy descriptions of defining characteristics, saddling even a commonplace plant like the briar rose with the cumbersome title of Rosa sylvestris alba cum rubore, folio glabro. Common names offered no more clarity, being specific to particular countries or even regions.

It was left to the actual, Swedish, Linnaeus to rationalize scientific nomenclature in the eighteenth century. Linnaeus’s masterstroke was realizing that plants did not need to be described, but could be simply designated using just two Latin words to denote a plant’s genus, and its unique species. Thus the briar rose became the easy-to-remember, perfectly distinguishable Rosa canina.

As professor of botany at Uppsala University, Linnaeus made taxonomy his life’s work, dispatching his students (known as ‘apostles’) to procure specimens from around the world, and promoting his ideas in books, such as his 1753 Species Plantarum, in which he named and categorized some 1,000 genera and 6,000 plant species. No wonder he felt able to boast, with characteristic immodesty, ‘God created, but Linnaeus organized’.

Over two centuries after his death in 1778, Linnaeus is still organizing. His binomial system became the international scientific standard for naming plants and animals, and many of his original names live on, too, his Species Plantarum having been designated the earliest acceptable source by the International Code of Botanical Nomenclature.

Linnaeus’s method of classifying plants according to the number and arrangement of their sexual parts proved less enduring. Condemned as ‘loathsome harlotry’ and disliked for its artificiality in some quarters, Linnaean taxonomy gained some currency, but within a century had been superseded by ‘natural’ systems, such as those devised by Antoine-Laurent de Jussieu in France, and by George Bentham and Joseph Dalton Hooker in Britain, which took into account a range of plant characteristics.

The arrival of DNA sequencing in the 1990s upset the taxonomic apple cart, revealing evolutionary relationships between plants previously thought to be unrelated.

A new, molecular-based classification system, the Angiosperm Phylogeny Group (APG I), was launched in 1998; the latest revision, APG IV, was published in 2016. Thanks to the group’s findings, whole plant orders have been deleted, new ones created and an array of garden stalwarts reassigned to different genera – and renamed accordingly. Grudgingly, gardeners now have to remember that Michaelmas daisies, known from Linnaean times as asters, must now be referred to as Symphyotrichum, that Senecio now goes by Brachyglottis, and that Schizostylis are actually Hesperantha. Perhaps there’s something to be said for common names after all.

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Reprinted with permission from The Compendium of Amazing Gardening Innovationsby Abigail Willis and published by Laurence King Publishing, 2018.

Mother Earth Gardener
Mother Earth Gardener
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