Unusual interrelationship between pare earth element and calcium contents in fern leaves

Since the rare earth elements (REE) are most informative as isomorphic repl acements of Ca2+ in organisms, we analyzed these elements in 142 fern leave s collected from several sampling sites in Japan by instrumental neutron ac tivation analysis (INAA), and the correlation between the REE and Ca conten ts was examined. In most cases, between any particular REE and the Ca conte nts, the correlation in the logarithmic scattering diagram was expressed as a single line parallel to the vertical (Y) axis. However, the detailed ana lysis of the diagrams characterized with respect to the sampling sire revea led that the 142 ferns could be separated into two or three groups on the b asis of their different REE/Ca ratios. The sampling sites where the differe nt REE/Ca ratios were observed completely agreed with those found in the pr eceding report, i.e., regarding the unusual correlation between Eu and thr other REEs.