Lycopodium clavatum is a spore-bearing vascular plant, growing mainly prostrate along the ground with stems up to 1 m (39 in) long; the stems are much branched, and densely clothed with small, spirally arranged microphyll leaves. The leaves are 3–5 mm long and 0.7–1 mm broad, tapered to a fine hair-like white point.
The spores of this moss, "lycopodium powder", are explosive if present in the air in high enough densities. They were used as flash powder in early photography and magic acts.