We have used atomic force microscopy to investigate the patterns obtained by isothermal crystallization of quasi-2-D monolayers of poly(ethylene oxide) adsorbed onto bare silicon wafers. These monolayers were prepared by a pseudo-dewetting process. Fingerlike branched structures were observed with a characteristic width which increased rapidly with crystallization temperature. The patterns are explained by a simple model considering the interplay of transport on the surface and the probability of attachment to the crystal. The influence of molecular weight was also studied. The average stem length increases with increasing temperature for the longer polymer. The shorter one crystallized in the (almost) fully extended form for all temperatures investigated. Temperature jumps during crystallization resulted in patterns with two different length scales. (C) 2000 American Institute of Physics. [S0021- 9606(00)50309-2].