Species:

Note: This is an invasive species in Europe, and it was recorded in Norway for the first time in 1988 (attached individuals). It is easy to recognize by the small, round gas vesicles, and by the serrated blades which are present during the first part of the growth season. It starts to grow in early spring by forming a long main axis, from which a high number of side branches subsequently forms. An individual can grow to several meters. In summer it produces receptacles, and the germlings start to develop while still attached to the receptacles. During autumn the thalli undergo senescence in the northern part of the species’ distribution area, and many branches break off and eventually lose the floating ability. The basal part of a thallus can over-winter.