Poa alpina; the Alpine Meadow-grass can be recognized immediately by the viviparous nature of the inflorescence. From the spikelets new plants emerge very soon. Also quite characteristic are the culm leaves. These are short, broad and pointed at the apex.
It is common all over Iceland but is more often found at higher altitudes.
The Alpine Meadow-grass is a member of the grass family (Poaceae, also known as Gramineae). The Icelandic name of the Alpine Meadow-grass is Fjallasvefgras.
A very similar species is Poa x jemtlandica, the Jemtland Meadow-grass (Icelandic: Hjallasveifgras). It differs by having nodding panicles and narrower culm-leaves. It is similar in vivipary. It is rather rare confined to higher altitudes.