Two subspecies exist of this Common Water-crowfoot: R.a. var. aquatilis en R.a. var. diffusus. With the first one the floating leaves are more or less kidney-shaped, the submerged leaves are elongated, thin and forked-parted. Sometimes leaves in an inbetween form occur. The submerged leaves may miss too. With var. diffusus mainly just finely-parted submerged leaves appear. The white, quinary little flowers differ slightly per variety. Frogs prefer to lay their eggs on the leaves. After flowering the plant may withdraw in its roots for sometimes quite a period. After even a year suddenly new leaves emerge. Rich flowering. Good winter-hardy. Likes slightly acidic water.