The Interactive Key to the Genus Croton of Madagascar and Comoro Is. is an identification system for all 149 native species to Madagascar and Comoro Is. The characters were derived from descriptions in an unpublished manuscript "The Genus Croton in Madagascar and Comoro Is." by A. Radcliffe-Smith.
The whole manuscript was marked-up into different styles using macros in MSWord. Each style represents roughly a field in an Access database. The transformation from MSWord to Access was performed using XML and XSLTs (XMLSpy and Mapforce). In the database the five chosen characters were coded using simple queries and find and replace function. This information was then extracted from the database into text files which were subsequently transformed into INTKEY format using DELTA.
Warnings and caveats
The taxonomic work by A. Radcliffe-Smith is currently under revision by Paul Berry (University of Michigan) and Petra Hoffmann (Royal Botanic Gardens Kew). Paul Berry is currently working to add further characters to this key. Any taxonomic changes made through this revision will be added to this key.
There are currently 5 characters included in the key: distribution (at the province level within Madagascar and Comoro Is.), lamina width and length, habit and leaf arrangement. The characters we have chosen are relatively easy to assess from any reasonably intact specimen, and are readily interpreted in conjunction with character state notes and illustrations.
Hints on using the key
If in doubt about a particular character (either your interpretation of the character or its presence on the specimen), then this character should be skipped to avoid risk of misidentification. Proceed in answering as many questions as possible until you only have one or a few species left in the remaining list, or you have run out of questions to answer. If only one species remains, check your identification by comparing your specimen with the species description, notes and images (click on the species names to reveal any additional information). It is advisable to use as many characters as possible as a means of checking the identification. If more than one species remains in the list you will need to compare your specimen with the additional information of all listed remaining species, or ask the program to compare the remaining taxa (click on the box above the list with the two overlapping circles). The additional information will often make it possible for you to make a positive identification of your specimen. Our testing of the Interactive Key to the Genus Croton in Madagascar and Comoro Is. has suggested that generally by using all 5 characters it results in groups of under 10 species remaining. Distribution is the best character in separating most species, followed by lamina width. Usually these groups of species can only be readily recognized by features not included in the key's character list. In these cases it is often possible to make a correct identification by comparing the specimen with the included images and/or description.
This is a continuing small project and we welcome comments and contributions so that we can improve and update our key. If you have comments or you would like to point out improvement, please do not hesitate to email and write to Patricia Malcolm, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK. All contributions will be fully acknowledged on the website.