STRUCTURE OF SALT GLANDS OF PLUMBAGINACEAE. REDISCOVERING OLD FINDINGS OF THE 19th CENTURY: ‘METTENIUS’ OR ‘LICOPOLI’ ORGANS?

Salt (chalk) glands of Plumbaginaceae represent interesting structures involved in the excretion of calcium carbonate outside plants’ organs, especially on leaves surfaces. These chalk-glands, nominated by some authors as ‘Licopoli’ or ‘Mettenius’ organs are also very important from taxonomical point of view. Their structure has been a matter of debate for decades and a historical analysis reveals that there are still some inconsistencies regarding the contributions of earlier botanists in discovering and describing chalk-glands. The present work tries to provide a picture of historical progress recorded in the 19th century related to investigation of these structures, focusing especially on the two important names usually mentioned in relation to them: Mettenius and Licopoli. In this respect, several useful clarifications are made, with emphasis on the role played by the two botanists in the stimulation of research interest for these glands among the generations of botanists to come