Casparian band-like structures in the root hypodermis of some aquatic angiosperms

Casparian band-like structures were detected in the root hypodermis of Potamogeton pectinatus L., Ruppia maritima L., Zostera capensis Setchell, Z. marina L., Z. japonica Aschers and Graebn, Halophila ovalis (R.Br.) Hook f. and Nymphaea capensis Thumb, but not in Egeria densa Planch, Eichhornia crassipes (Mart.) Solms and Lema minor L. The bands stained with the fluorochrome berberine hemi-sulphate which is specific for Casparian bands. They also contained suberin, resisted acid digestion and had an ultrastructure resembling Casparian bands of the endodermis. They were always associated with suberin lamellae, and blocked apoplastic transport into the interior tissues of the roots. Symplastic transport through the root tissues, however, was not affected by the bands' presence.