Acorus calamus (Sweet flag)

Acorus calamus (Sweet flag) is a clump-forming green rush with sweetly scented leaves, steadily spreading in shallow water or wet ground. Non-invasive and useful for natural swimming ponds as it produces little debris. Diehards would say that it is not native, since it was not present before the last Ice Age, but it has been around for several hundred years. Good for natural understated planting schemes.