Eriophorum angustifolium; Common Cottongrass grows all around Iceland in marshes. Contrary to its name it is not a true grass but a sedge. Once the fruits mature the hairs grow very long and becomes a very recognizable sedge. A resembling species is E. scheuchzeri, Scheuchzer's cottongrass. Common cottongrass has multiple spikes on each flowering stem whereas Scheuchzer's cottongrass has only one spike in a single flowering stem.
It is a member of the sedge family (Cyperaceae). The Icelandic name of this species is Klófífa.