Classification: systems and philosophies

The first classification systems for plants relied solely on visible characteristics. They were often somewhat artificial, although easy to apply for identification purposes. Later systems aimed to be more natural, ideally reflecting plant evolution closely, and this has involved the use of cryptic characters, such as chromosome details and molecular information such as DNA sequences. However, cryptic characters, though ostensibly more natural, are of little use for plant recognition. The invaluable concepts of species and genus have also often proven to be rather artificial, and this ‘binomial’ system, used for plant names since Linnaeus, has been under threat, supplanted by inconsistent, often dysfunctional hierarchies. Therefore, the path to scientifically rigorous and fully objective methodologies may lead to abandonment not only of the use of morphological characters that allow plant recognition, but also the loss of the the binomial principal of names for species and genera.

Despite this trend, plant evolution has often been so complex that a fully natural system has proven much more difficult to elucidate than expected, especially at the business end of the rankings-genera and species, and especially for groups that interbreed freely to give a reticulate evolution pattern, such as the bamboos. When the new classifications fail to be accurate, consistent, or conclusive, the wisdom of abandoning more pragmatic but slightly artificial systems is called into question. Fortunately for the users of plants and their names, the good old systems of species and genera classified by old-fashioned visible characters, have never really gone away, and are currently witnessing a resurgence, strengthened by the evolutionary insights given by molecular investigations, but not supplanted by them.

Available molecular trees Ní Chonghaile et al.  Temperate bamboo combined tree from Dublin & Kew Guo et al.         Temperate bamboo trees from China Triplett & Clark     Examples of online molecular trees (use Firefox browser)

Phenetic classifications have traditionally been applied in the descriptions produced for flora treatments, accompanied by keys and illustrations of the characters used to distinguish plants. Molecular analyses are usually expressed in trees known as cladograms, and results are not necessarily incorporated into the naming, description, or identification of plants. Opinions differ as to how much molecular data is relevant or useful. Trees from recent molecular research on bamboo phylogeny are presented on this site, from work in the British Isles and China. Such trees are being incorporated into Treebase, an online database of considerable complexity. .   ... More