The experimental taxonomy of Salicornia L.

The annual species of Salicornia have always presented major taxonomic difficulties which have never been solved. Investigations by other workers had shown that the currently accepted classification was highly unsatisfactory. The first part of this investigation was concerned with an analysis of the morphological characters of the Salicornia plant in an attempt to find consistent and reliable characters. This was carried out in two main ways. Firstly, by making extensive collections of plants from a number of localities in the British Isles, dividing these into morphologically homogeneous groups and determining the chromosome numbers, and then correlating the morphology with chromosome number. Secondly, by cultivation on plants from these populations, it was possible to determine the extent of phenotypic variation in the field, and to determine which characters appeared to be little affected by external conditions. The results from these investigations made it possible to divide annual Salicornia into two groups on morphological and cytological grounds. The diploid group was originally divided into 3 species, but subsequent investigations suggested that at least two of these should be combined, although their precise status is still uncertain. The tetraploid group was originally divided into 4 species. Once again subsequent investigations led to the conclusion that two of these should probably be combined, but that the remaining 3 species were reasonably distinct, although their precise delimitation was not always clear.