Relation between Stipe Length, Environment, and the Taxonomic Characters of Laminaria

Abstract

The characters normally used to separate Laminaria longicruris from L. agardhii are unsatisfactory because they change with the stipe length of the plants (presumably related to age) and the degree of wave exposure, and because forms with characters intermediate between the two species are common. At four stations with differing degree of exposure, young plants all had solid stipes and some of the older plants had hollow stipes, but the length at which a cavity first appeared increased with increasing wave action, while the proportion of the stipe that was hollow decreased. The shape of the base of the blade did not correlate with the condition of the stipe.