540 x 540
This drawing of Pteris cretica (the cretan brake fern) is bounded by the hexagon. The space within is divided by a close packing grid of hexagons and equilateral triangles. The triangular spaces vary from the completely filled black triangles at the top to the empty triangles at the bottom. This is not a simple change from light areas to dark areas but takes an asymmetrical striped form. The hexagonal spaces are windows on a continuous line drawing of the eccentrically placed Pteris cretica.