Towards a global checklist of the world gypsophytes : a qualitative approach

Interest in plants growing on special substrates has increased considerably in recent years. The studies on halophytes (plants restricted to saline soils) and serpentinophytes (those restricted to ultramafic rocks) are good evidence of this trend. Research on the phenomenon of gypsophily has not been developed as widely as the other two before-mentioned fields, but important progress has been reached. The existence of a global database about gypsophytes and territories with gypsum substrates would imply a big leap in quality. The bibliographical criterium was selected in order to build this compilation as the only preliminary way to face the problem. According to the research about reviewing of distribution and ecology patterns of 209 taxa, it is possible to asure that there are gypsum outcrops in 112 countries. In 71 of those countries some clues point to the existence of a flora on gypsum, in which clear and undoubted cases of plant species directly related to gypsum soils in 53 countries have been found. These results show, on the one hand, the need of a deep correction to increase the data contained in previous reviews on gypsum outcrops distribution and, on the other hand, the diffussion of gypsophily phenomenon in plant species. Although the presence of genuinely gypsophyte taxa is much higher in dry climates, gypsum outcrops also show floristic peculiarities in wet climates, such as a refuge for xerothermophilic taxa, which clearly fits within the phenomenon of gypsum edaphism.