Fern Crozier


Ferns of Thailand, Laos and Cambodia




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Floras such as the Flora of Thailand and Flore du Laos, du Cambodge et du Vietnam seek to catalogue and describe all of the vascular plants in their regions but, while they are an effective way of providing baseline biodiversity data, they are not conducive to being regularly or quickly updated as further exploration and collecting brings new taxa or new records to light or new research changes taxonomic concepts.

Making accurate and usable identification keys is a fundamental aim of floristic research. Traditionally these have been presented in the form of dichotomous printed keys that have often been written by specialists for similar specialists and contain very little explanatory information. More recently a number of computer programmes have become available that make it much easier for specialists to create user-friendly, computer-based, multi-access (interactive) keys and other electronic identification tools that are of use and interest to a broader range of people and professions. The principles of these have been set out by Dallwitz et al. (2005) and the possibilities for the future, including electronic field guides, have been discussed by Agarwal et al. (2006).

In a traditional dichotomous key to any group of plants the user must move sequentially through a number of steps and at each step must select one of two options that most appropriately describes the plant being identified. If the number of taxa is small and, for angiosperms, the plant is both flowering and fruiting this often works well. However, for most plant groups keys will not work if the plant is sterile or if the material to hand is inadequate for all the steps in the key. If, for example, the first dichotomy in a key to ferns asks about rhizome scales but the user has only fronds or it asks about venation but the user has no microscope then the key is unusable and the fern will remain unidentified.

The advantage of an interactive key format is that the user chooses which character to use first and which characters to use subsequently. The programme will inform the user which characters best separate the remaining taxa but if those characters are not available any character may be chosen and taxa will be eliminated at each step depending on the character states chosen. Eventually only one taxon will remain.