Helosciadium inundatum

Helosciadium inundatum, known as lesser marshwort, is a small, slender, semi-aquatic annual or short-lived perennial herb of the family Apiaceae found in shallow, seasonally flooded pools, ditches, and pond margins. The weak, hairless stems creep or float, rooting at the lower nodes and producing two distinct leaf forms: submerged leaves are finely divided into thread-like capillary segments, while emergent or floating leaves are pinnate with small, wedge-shaped, three- to five-lobed leaflets. Tiny white flowers are borne in sparse compound umbels of just two or three short rays opposite the leaves, producing small ovoid ridged fruits. It is widespread but local across western and central Europe, North Africa, and parts of western Asia, and is considered scarce in much of its range due to loss of acidic, oligotrophic wetland habitats.