Figs. 2–13

Dictyota dichotoma. Vegetative and reproductive structures. 2 Habit of a thallus in nature. 3 Detail of terminal portions showing dichotomous branching, rounded apices and smooth margins. 4 Detail of a perpendicular proliferation arising from the thallus surface associated with tissue rupture. 5 Transverse section of a thallus showing the unilayered cortex (C) and the medulla (M). 6 Detail of the thallus in surface view showing rectangular cortical cells with numerous discoid chloroplast. 7 Detail of a sporophyte in surface view to see dark brown, subspherical sporangia. 8 Detail of two sporangia, one of them empty, in a transverse section of a sporophyte. 9 Scanning electron micrograph of a male gametophyte in surface view showing three mature antheridial sori. 10 Detail of a mature antheridial sorus. Antheridia were arranged in regular rows. 11. Detail of antheridia under scanning electron microscope. 12. An antheridial sorus after gametes release; a ring of paraphyses persists 13. Oogonial sorus. Scale bars: Fig. 2, 3 cm; Figs. 3, 4, 50 mm; Fig. 5, 30 μm; Fig. 6, 15 μm; Fig. 7, 60 μm; Fig. 8, 40 μm; Fig. 9, 200 μm; Fig. 10, 100 μm; Figs. 11, 12, 20 μm; Fig. 13, 150 μm