Name that Holdfast - Part 2

Those of you who were reading the blog last spring might remember the Name that Holdfast game.  Here's a new addition.

If you haven't played before, below is the holdfast of a local marine alga — can you guess which species?  This one is from Pinnacle Gulch on 26 June 2013.  [Warning: The answer is directly below the image.]

 

And the answer is:  Laminaria sinclairii !

This is a wonderful kelp.  I neglected to take pictures of the entire seaweed this morning, so here are a few from the past.  The next two photos are from Bodega Head.

Laminaria sinclairii has long narrow blades in a very deep brown color:

 

This kelp is unusual in that it's rhizomatous, so it can grow in very dense patches.  Below it's covering the larger boulders on the left side of the image.

 

P.S.  Thanks to Peter for pointing out the nice holdfast arrangement this morning!