Fluorescence histogram of propidium iodide-stained nuclei isolated from fresh leaf tissues of Oldenlandia affinis seedlings. Glycine max 'Polanka' (2C = 2.50 pg) was used as an internal reference standard. Nuclei from the sample and the standard were simultaneously isolated, stained, and analysed. The actual ratio between both peaks in this histogram is 3.42. Each plant was re-estimated three times on different days.