Effect of dissolved calcium on the formation of secondary attachment structures in different types of branches of Chondracanthus chamissoi (Rhodophyta, Gigartinales)

development of secondary attachment structures (sas) was evaluated in apical fragments of pinnules, and basal and lateral branches in the carrageenophyte chondracanthus chamissoi. when no dissolved calcium was added to the culture medium, most basal and lateral branches initiated sas formation, while most pinnules remained unchanged. calcium addition greatly increased the proportion of fragments developing sas, and also increased the stage of development achieved by sas in all branch types. we suggest that sas formation by basal branches contributes to a complex attachment system. sas formation by lateral branches and pinnules may contribute to vegetative propagation following fragmentation of thalli.