In a cytological study of Eudesme virescens (Chordariaceae) it was noted that the vegetative sporophytic cells possess ultrastructural characteristics typical of the Phaeophyceae: the association of three non-cohering thylakoids in peripheral and parallel bands within the chloroplast; the lack of thylakoids in the pyrenoid, if it is present; fucoidin and alginic acid vesicles; and oil deposits within some vacuoles. They also exhibit fine structural features which are generally associated with brown algal species in the lower orders: the presence of a prominent pyrenoid, perinuclear Golgi bodies, and even distribution of plasmodesmata through the cross walls. The presence of a pyrenoid sac, association of nuclear membrane and chloroplast endoplasmic recticulum, and existence of microtubules between the two chloroplast double membranes seem to be variable characteristics within the phaeophycean class.