Fig. 9. (A) Breaking forces of genicula from three representative fronds as functions of the planform areas of distal frond segments supported in flow. (B) Diagram of hypothetical Calliarthron frond, explaining the pattern of decreasing slope with increasing frond size. 1x, 2x and 4x refer to the number of new growth units distal to genicula in the specified regions. See text for details.