AbstractDetached fragments of the aquatic mossesFontinalis duriaeiandHygroamblystegium fluviatilecan attach to rocks and tree branches. A period of at least 9 weeks in association with a new rock substrate is required for attachment to occur, under the conditions of the experiment. Following the initiation of attachment there is a great increase in attachment activity resulting in a network of rhizoids; this quickly diminishes after 12–13 weeks. The overall behavior closely parallels the hyperbolic behavior pattern of several species colonizing an artificial new island (Schoener, 1974) and the curve shape appears to be a universal one where the attachment rate can be expressed asY=Ymax- aeb(t−w)where the rate of attachment (b) averages somewhere near−.5, but is influenced by other variables, including substrate type; a is the fraction of moss which will attach between the end of week wand the time of maximum attachment;tis week number; andwis the week of first attachment.