Mediterranean clubmoss
Selaginella denticulata
Family · Selaginellaceae · Harmless
The bright green mat of scale leaves lining wet stone and well walls, looking like moss but not being one: it is a vascular plant three hundred and fifty million years old.
Walls and rocks · Streams and ditches · Uplands · Oak woods
Also known astoothed spikemoss
How to tell it
Fine creeping flattened stems, branching in one plane. The leaves are minute scales one to two millimetres, in four rows: two of larger leaves spread sideways and two of small leaves pressed along the middle. Bright glossy green, always on damp shaded stone.
What it is confused with
No dangerous lookalikes known in the Iberian Peninsula.
What it is for
No use. It matters as a living fossil: it belongs to a lineage that dominated the Earth before flowering plants existed, and still reproduces by spores of two sizes, which almost nothing else does.