Morphological variation, chromosome numbers, reproductive system and ecology were studied in Galium palustre s. lat. in some areas in the Baltic land-uplift area. Two cytotypes were found; diploids with 2n = 24 and octoploids with 2n = 96. Each cytotype comprises a large amount of habitat-correlated variation. Despite this, it is fairly easy to destinguish morphologically between the two cytotypes. It is therefore suitable to treat the diploid cytotype as one species, Galium palustre s. str.. and the octoploid cytotype as another species, Galium elongaturn. Both species grow in wet places, such as ditches, lake-shores and wet woodland. There are practically no differences in habitat ecology between them, but a slight tendency can be discerned for octoploids to grow in localities which never dry out, while diploids can grow in drier localities. Only G. palustre s. str. grows on fairly exposed sea-shores. A morphologically distinct from can also be distinguished, including diploids from sea-shores and coastal areas below 5 m. a. s. 1. This ecotype is described as Galium palustre var. balticum var. nov. It is characterised by smooth or nearly smooth stems and short, narrow leaves. It has always a very rich flowering and fruit set, which may be regarded as an adaptation to coastal conditions.