Morphological and histo-anatomical traits reflect die-back in Phragmites australis (Cav.) Steud

The decline of Phragmites australis (Cav.) Steud., a well-known phenomenon in Central and Western Europe, was detected recently also in the Mediterranean Basin. A range of parameters were quantified in healthy and affected stands as a screening for indicators of die-back. These were: stem dimension, density and pattern, starch storage, presence of occlusions in the vessel cells, abnormal lignification and calli in the root parenchyma. First, high stem density, occlusions, lignification and calli did not always coincide with die-back. Second, starch content appeared a reliable indicator. The higher starch amount detected in the healthy stands can be related to the greater ability to perform photosynthesis and accumulate reserves. Furthermore, the starch lack detected in the declining stands might result from the increased starch demand, due to the shoot regeneration connected to the clumped habit. (C) 2012 Elsevier B.V. All rights reserved.