Fig. 2
Embryological survey of the flower bud (A–D) and flowers from open pollination (E–H) and parthenogenesis (I–L) experiments for D. incarnata. In the case of open pollination, similar stages of embryo development were observed in the other species studied. (A) Division (arrow) in uppermost nucellar cell to create archespore. (B) The archesporial cell that started to differentiate into megaspore mother cell. (C) Mmc at prophase I of meiosis. (D) Two-cell pollen grain in pollinia. (E) Prophase I, 24 HAA. (F) End of megasporogenesis 48 HAA; the lower most positioned functional megaspore and the remains of megaspore triad/tetrad (star and arrowhead). (G) Start of megagametogenesis 5 DAA; the division in one-nucleate FM/FG; the remnants of degenerated megaspores are marked by star. (H) Empty ovary 10 DAA. (I) 24 HAE; irregular meiosis at metaphase I; losing bivalent/chromosome marked by arrowhead. (J) 48 HAE; anaphase I. (K) 48 HAE; the asymmetric dyad (arrow); the micropylar cell of the dyad is much smaller than chalazal one. (L) Degenerated ovule inside the ovary 10 DAE. arch-archesporial cell; mmc-megaspore mother cell; vn-vegetative nucleus; gn-generative nucleus; ii-inner integument; oi-outer integument; FM-functional megaspore; FG-female gametophyte. Bar = 20 µm for (A–G, I–K) images.
