This is the first indication of a conducting foliar strand or leaf bundle and forms an approach to leptom, though it is not so specialized as the leptom of the higher Phaeophyceae.
The chloroplasts are generally distinguished by their green color, which is due to the presence of chlorophyll; but in many Algae this is masked by another coloring matterPh ycoerytlsrin in the Florideae, Phycophaein in the Phaeophyceae, and Phycocyanin in the Cyanophyceae.
A similar uncertainty exists with reference to certain groups of Phaeophyceae, and the matter will thus arise again.
The intercalated growing region of Laminaria affords an example of another variety of growth in Phaeophyceae.
Many are epiphytic on other algae, more especially the larger Phaeophyceae and Rhodophyceae.