Foredunes are the older and higher dunes that that run parallel to the shore just inland of the embryo dunes. The foredunes are also referred to as yellow dunes because of the high proportion (c. 20%) of visible sand. The foredunes are floristically species-poor, with large tussocks of marram grass (Ammophila arenaria) locally dominant and other early colonising plants such as dewberry (Rubus caesius) playing a stabilising role. Sea holly (Eryngium maritimum) and sea spurge (Euphorbia paralias) are common associates in this habitat, and sea stock (Matthiola sinuata) can also be found on some of the southern dune systems in Wales.