is a dioecious perennial herb inhabiting marshy places or wetlands,
the stems erecting without branching; those occurring in the water
measure approximately 50cm long, those in wetlands 5-20cm in size.
Leaves, deeply pinnatifid, are in a whorl, each 0.5-2cm in length;
the lobes are linear. With male flowers, petals are 4 in number,
sepals are in the shape of a bell, stamens 6-8 in number, while in
female flowers, petals drop off early, and stigmata are plumous.
Bloom time: June-August.