Complex sentence: Penjing has less emphasis on technical perfection, and the art is not as rigidly categorized as the art of bonsai, and such things as tangled roots or pruning scars (which are against the bonsai aesthete) are allowed if it fits the overall design.
Split into simpler sentences: Penjing has less emphasis on technical perfection, and the art is not as rigidly categorized as the art of bonsai. Tangled roots or pruning scars (which are against the bonsai aesthetic) are allowed if they fit the overall design.