This is less zigzagged than other zigzag weeds and has more slender branchlets. There are wide spaces between the branches and the stipe here is often twisted. It has round air bladders on the branchlets which are on side branches. It is dark grey brown. It is that largest of the zigzag weeds reaching about 1.5 m high.

Usually sub-tidal but can be found in large rock pools and at the edge of the water on exposed coasts. It is found in NZ and Australia.

A producer using the sun for photosynthesis

Photo Credit: Rod Morris. Photos available from www.rodmorris.co.nz