Puccinellia maritima; the Saltmarsh-grass is characterized by tufts from which grow extensive creeping stems. The blossom at maturity is always more or less contracted or forward-pointing. This is an easy differentiating characteristic from Puccinellia distans ssp. borealis (Refelexed Saltmarsh-grass) that has spreading and reflexed flowering stems from the main stalk.
The Saltmarsh-grass is common along sandy and rocky shores. It requires saline or brackish soils.
The taxonomy of Puccinellia species is rather complicated. On Iceland two distinct types (species) occur, the "maritima"-type and the "distans"-type. In the popular field guide "Flowering Plants and Ferns of Iceland" by Hörður Kristinsson (3rd ed) they are named P. capillaris (the "distans"-type) and P. coarctata (the "maritima"-type). P. capillaris is an older synonym for P distans ssp. borealis. I am not sure if the English for P. distans ssp borealis quite correct as Reflexed Saltmarsh-grass is applied to both P. distans ssp distans and ssp borealis. If you think this is confusing, well lets now turn to the other species i.e. the one described on this page. In the mentioned field guide it is called P. coarctata. However this name is also known as an old synonym of P. distans, not maritima! It is interesting to see that in the 2nd edition of the mentioned field guide the names P. distans and P. maritima were used. So in order to evade all confusions I stick with P. distans (but clearly mention that it is the subspecies borealis that grows on Iceland) and P. maritima.
The Saltmarsh-grass is a member of the grass family (Poaceae, also known as Gramineae). The Icelandic name of the Saltmarsh-grass is Sjávarfitjungur.