Carex lyngbyei; the Lyngbye's Sedge is one of the larger sedges on Iceland. According to sourcesIt can grow to more than a meter high. I have noticed that on Iceland it rarely exceeds 50 tot 75cm. There is only one other common sedge on Iceland that compares in height, being the Bottle sedge (Carex rostrata). They are easily differentiated: Lynbye's sedge has drooping female spikes whereas the Bottle sedge has stiff upright spikes. Both species grow abundantly in lakes, ponds and marshes. However there are some gradual differences in habitats: the bottlesedge is seen moreoften along pools where the Lyngbye's sedge is found more often in marshy grasslands. The Lyngbye's sedge grows in lowland regions. Carex lyngbyei is an American species, naturally growing on Iceland but missing in mainland Europe. There is a close relative species - by some regarded to be a hybrid of lynbyei x subspathacea being the Ramensk's sedge (Carex ramenskii - Icelandic name: Marstör). Alas I have no photo yet. This species probably resembles the common sedge (Carex nigra) but has the typical pointed scales of C. Lyngbyei on the female spikes.
The Lyngbye's sedge is a member of the sedge family (Cyperaceae). The Icelandic name of this species is Gulstör.