In the Gulf of California Figure 9. Gulf of California Si cycle due to the Diatoms concentration in the ocean. Brown algal walls are composed of cellulose fibrids and the commercially important mucopolysacaride alginic acid . No unicellular or colonial browns, the simplest are the branching filaments , and the longest organism are kelps . Simple filaments form little cellular differentiation while Kelps form lots of cellular differentiation.
More complicated forms have cortex and medulla .
Cortex is the outer layer of thallus with photosynthetic cells. Growth is either diffuse or at the meristem . Meristen is the region where new cell are produced, these can be defined as apical or terminal or interlayer within a branch. In fact simpler forms look alike complex forms look different. Other brown algae have distinctly dissimilar haploid and diploid stages.