As part of a long-term study on the development and structure of the cortex of the roots of wetland plants, adventitious roots of Caltha palustris were examined. The cortical portion of the root apical meristem was divided into two general regions: a layer of inner cortical initials which produced about half of the cortex by periclinal divisions in its innermost layer, the proendodermis, and an outer, open-meristem region which was associated with the base of the rootcap columella and, which, by periclinal divisions in multiple layers, produced the outer half of the cortex, including the hypodermis. Each cell of the endodermis had a Casparian band, but produced no further wall deposition. The bulk of the cortex was comprised of parenchyma cells which accumulated starch, and limited schizogenous aerenchyma formed in old roots. The hypodermis was biseriate, and its outermost layer developed into a uniseriate exodermis with broad Casparian bands and, later, complete suberin lamellae at maturity.

Key words: Caltha palustris, root anatomy, root apical development