Kelp

Kelp

Observation - Kelp - UK and Ireland. Description: Although it is striped, I am not sure if this is age or habitat caused. Several fronds found washed up after a high tide quite a distance from each other, but all with the same stripes. The smooth stalk indicates some variety of digitata, is this correct

Although it is striped, I am not sure if this is age or habitat caused. Several fronds found washed up after a high tide quite a distance from each other, but all with the same stripes. The smooth stalk indicates some variety of digitata, is this correct?