Histograms of relative fluorescence intensities in Porphyra. Examples of histograms of relative fluorescence intensities obtained through simultaneous flow cytometric analysis of propidium iodide-stained nuclei of Porphyra (peaks 1–4) and internal reference standard S. lycopersicum (peak at the right; with 2C = 1.96 pg). X-axis: Fluorescence (channel number). Y-axis: nuclei counts in each sample. (a) Triploid gametes in P. dioica. (b) Octoploid zygotospores from a tetraploid cytotype in P. umbilicalis. (c) Mixoploid cytotype 2x/4x in P. linearis. (d) Mixoploid cytotype 3x/4x in P. linearis. (e) Male gametes 3x and 4x. (f) Multiploid gametes 4x in P. dioica. Insets show cytograms of side scatters in logarithmic scale (sslog, axis x) vs. Propidium iodide fluorescence (PI, axis y) of nuclear suspensions of the same samples.