Description: Thallus is a reddish (pinkish) brown to purple strap-shaped blade, one cell layer thick, that often reaches 100 cm (39 in) or more in length and 30 cm (12 in) broad. Spermatangia and zygotosporangia occur in wide marginal or submarginal bands or streaks. Habitat: This species grows on the stipe of the bull kelp, Nereocystis luetkeana, rarely on other hosts; it is always submerged. Similar taxa: Wildemania amplissima occasionally also grows epiphytically on Nereocystis.