Figs. 31–37. Light micrographs showing stages of the free nuclear phase of endosperm development in Platanus racemosa. All sections are longitudinal and oriented with chalazal end toward top of page (except Fig. 37 ). Figure Abbreviations: A, antipodal cell; CZ, chalazal zone; MZ, micropylar zone; V, central vacuole. 31. Fertilized female gametophyte with primary endosperm nucleus in late telophase (arrow). Scale bar = 50 µm. 32. Higher magnification of dividing nucleus in Fig. 1 . A forming cell plate is present (arrow) between daughter nuclei, but will not form a persistent cell wall. Scale bar = 10 µm. 33. Recently separated daughter nuclei of primary endosperm nucleus division with no cell plate. Scale bar = 10 µm. 34. Free nuclear endosperm consisting of a parietal layer of nuclei and cytoplasm surrounding a central vacuole, zygote present. Scale bar = 10 µm. 35. Free nuclear endosperm stage slightly later than in Fig. 34 with chalazal zone. Scale bar = 10 µm. 36. View of chalazal zone and one persistent antipodal cell. Scale bar = 20 µm. 37. Transverse section of ovule with free nuclear endosperm. Three endosperm nuclei in a parietal layer of cytoplasm surrounding the central vacuole. Scale bar = 25 µm