A simple experimental model on the basis of the Belousov-Zhabotinsky (BZ) reaction was produced for the study of wave patterns in a spatially growing excitable medium. A drop of sulfuric acid, placed onto a millipore filter soaked with low-acid BZ solution, expanded with time and made the system excitable. New patterns of flower-like propagation were observed at the frontier of a growing excitable spot. Initially plain circular wave fronts, when expanding, changed to a crown of petal-like propagating fragments of excitation waves. The overall symmetry of the system spontaneously changed with time.