Fig. 1.

Typical biphasic life cycle of Laminarialean kelp. When mature, large diploid sporophytes develop sori over the lamina, composed of sporangia and paraphysis (PA). Motile zoospores, generated in the sporangia by meiosis, are further released into the water and develop into independent haploid female or male gametophytes. Both sexes can multiply vegetatively (AX) by disruption of the filaments. The production of eggs and sperms is followed by fertilization and the development of a new sporophyte. Scale bar 5 µm, although a large sporophyte can grow over 2 m long