In many of the landscapes we’ve visited in Iceland we have found loose mounds of ash from eruptions, black sand dunes or debris from glacial meltwater streams. One plant which happily colonizes this unstable, well-drained ground is Lyme grass (Leymus arenarius), a tall grass with distinctive blue-grey leaves.
Clumps of this grass will spread, growing new shoots from underground rhizomes and so can create large swathes of vegetation across empty expanses of sands.
After the 1973 eruption of Eldfell in Heimay, Vestmannaeyjar, residents had to dig their town out of the tonnes of smothering ashes. To stop the material blowing off the volcano slopes and back into the town, they planted species such as this to bind the new surfaces together.
Lyme grass is tolerant of sea salt and tolerant of drought. It is found around Central and Northern Europe and has been introduced to many locations (such as N America). It is planted because of it’s ability or bind sand together, stabilizing environments such as fore dunes, but it’s spreading habit means that it can become invasive.