We investigated systematically the structure and growth of monolayers of physisorbed polybutadiene (PB) starlike polymers on freshly cleaved mica after solvent evaporation using atomic force microscopy (AFM). We observed a strong dependence of the evolution of the average island height and surface coverage with increasing surface density on the functionality (number of arms) of the star polymers. We explain these structural phenomena in terms of the molecular and conformational properties of the different star polymers. Our study provides real space observations of the star polymer surface structures near the overlap surface density for the first time. The structural regimes are strongly affected by the change of the star polymer behavior from polymer-like to colloid-like when the arm functionality increases.