Crassula helmsii is an aquatic or semi-terrestrial succulent that belongs to the Crassulaceae family. This plant was first found in New Zealand and Australia, but later it became known all over the world. It is known that Pigmyweeds belongs to the Global Register of Introduced and Invasive Species in many countries.
Crassula helmsii is a hardy plant that likes to grow near ponds and rivers, where it creates a carpet with a large coverage. Interestingly, the plant can completely or half submerge the stems in water.
It has stiff shoots bearing small narrow leaves 4–24 mm (0.16–0.94 in). The flowers emerge from the axils of the upper leaves and are formed in the summer. At the same time, they have 4 petals and are always above the water.