Abstract. Gypseous substrates are well-recognised as supporting distinctive and unique flora assemblages, including numerous gypsum endemic (gypsophile) species. Along with these, others are also frequent although their presence is not restricted to gypsum; they show a clear preference for them (gypsocline). While this phenomenon (gypsophily) has been studied regionally, and various hypotheses put forward to explain it, there has been little global synthesis. We present a preliminary check-list on the gypsophile and gypsocline flora of the Palaearctic and Australian areas as a part of a project to develop a global checklist of the World's gypsophytes, which can broaden our ecological and biogeographical understanding of these unique environments. The database contains 935 taxa spanning 54 countries. The Irano-Turanian region -and to a lesser extent the Mediterranean region-emerged as the richest territories in terms of gypsophile species; this richness was much reduced in the SaharoArabian and, especially in the Eurosiberian regions. The factors that can modulate the richness of gypsophytes in a region are discussed and have been distributed into four groups: a) geological and edaphic factors; b) factors linked to the insular nature of outcrops; c) climatic variables and their interaction with the soil; d) biogeographical factors. The importance of those factors linked to insularity and, especially, to water availability is emphasized. Because the soil structure of many gypsum outcrops reduces water ability to plants, such outcrops can be regarded as "dry-islands" surrounded by less xeric substrates. The fact that gypsophytes can be grouped within a few major flowering plant clades across continents, confirms their pre-adaptations to these harsh and unique environments. Our work provides a preliminary database for exploring ecological and biogeographic issues relating to gypsophily, and we hope it will stimulate global interest in these valuable ecosystems. Keywords: edaphism; global check-list; gypsicolous; gypsophile; gypsophyte; gypsophily. Un primer inventario de la flora gipsícola del Paleártico y de AustraliaResumen. Los sustratos yesíferos son sobradamente conocidos por presentar cortejos florísticos peculiares y exclusivos, lo que incluye a numerosos endemismos (especies gipsófilas). Junto a estas especies, aparecen otras también muy frecuentes cuya presencia no se restringe al yeso, pero hacia el que muestran una clara preferencia (gipsoclinas). Mientras que este fenómeno (gipsofilia) ha sido estudiado regionalmente, y se han sugerido varias hipótesis para explicarlo, apenas existen síntesis globales sobre el mismo. Aquí se ofrece un inventario preliminar de la flora gipsófila y gipsoclina de los territorios paleártico y australiano como parte de un proyecto que pretende desarrollar una checklist mundial, de manera que se contribuya a ampliar el conocimiento ecológico y biogeográfico de este ambiente único. Este inventario incluye 935 taxa distribuidos por 54 países. La región irano-turaniana -y en meno...

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The aim of this study is to identify the roles of free proline and soluble carbohydrates in water gypsum stress. This study is the first such study on gypsophyte and gypsovag plants. For this purpose, free proline and soluble carbohydrate contents in gypsophyteand gypsovag plants have been analyzed. It is known that proline increases under stress conditions and it is a nitrogen-containing compound with protective properties contributing to durability understress. Soluble carbohydrates accumulating under stress conditions, on the other hand, take on the protective task of regulating cell osmotic density. In gypsophytes, free proline is proportionally high (Ch/Pr:1.5 to 9.3) and the amount of soluble carbohydrates is low. In gypsovag individuals growing on gypsum, proline is proportionally low (Ch/Pr:25.5 to 9.2), but soluble carbohydrates are high. It is found that in gypsovag individuals growing on mediums other than gypsum, the amount of proline increases (Ch/Pr:11.6 to 8.5), but the proportion of soluble carbohydrate decreases. Accordingly, while gypsophytes adapt themselves to high proline amounts in response to water gypsum stress and gypsovags develop resistance to water gypsum stress with high amounts of soluble carbohydrates, it is observed that the Ch/Pr ratio in non-gypsum soils decreases.

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