Conditions here in Iceland are often unfavourable for plant growth. In parts of the country, barrens have formed as a consequence of long-term overgrazing and destructive natural forces. The highlands of Iceland have wide-ranging black deserts. Commonly, the soil is poor containing much sand and gravel. Sands are arid and infertile with rapid loss of nutrients and water. Among the successful plants on drifting sands are the tuft-forming, coarse Lyme-grass (Leymus arenarius) and the stoloniferous Fiorin (Potentilla anserina), binding the sand with rooting nodes.
On the gravelly barrens of both highland and lowland river banks you may find the exquisite River-beauty Willow-herb (Chamerion latifolium) bearing large, pink flowers. Muddy gravels may fragment into characteristic gravel polygons as a consequence of alternating soil freezing and thawing processes. On wet gravels you may find the delicate pink-flowered Hairy Stonecrop (Sedum villosum), the sturdy Two-flowered Rush (Juncus biglumis), the drooping Spiked Wood Rush (Luzula spicata), and growing from green rosettes the Tufted Saxifrage (Saxifraga caespitosa), cushion plants such as Thrift (Armeria maritima) and the pleasant, white-flowered Alpine Mouse-ear (Cerastium alpinum).