The stamen primordia and gynoecium primordia were dissected carefully and photographed using a LEICA S6D stereomicroscope (Leica Microsystems, Wetzlar, Germany). Then, the floral buds, stamen primordia, and gynoecium primordia were fixed in FAA for 24 h for SEM and paraffin sectioning. Some fixed materials were dehydrated in an ethanol series for 20 min per step and dried using CO2 as the exchange agent by an EMITECH K850 critical point dryer (Emitech, Canterbury, British). Then, the samples were coated with gold by an Edwards E-1010 ion sputter golden coater (Hitachi, Tokyo, Japan) and photographed with an FEI Quanta 200 scanning electron microscope (FEI, Eindhoven, Netherlands).
The remaining fixed materials were dehydrated in an ethanol series, transparentized in a xylene series, infiltrated in paraffin, embedded in paraffin wax, and sectioned at an 8 µm thickness with a LEICA RM2145 rotary microtome (Leica Microsystems, Wetzlar, Germany). Finally, the sections were stained with safranin and fast green and photographed with a Zeiss AXIO Axioscope A1 fluorescence microscope (Carl Zeiss, Jena, Germany).
The remaining fixed materials were dehydrated in an ethanol series, transparentized in a xylene series, infiltrated in paraffin, embedded in paraffin wax, and sectioned at an 8 µm thickness with a LEICA RM2145 rotary microtome (Leica Microsystems, Wetzlar, Germany). Finally, the sections were stained with safranin and fast green and photographed with a Zeiss AXIO Axioscope A1 fluorescence microscope (Carl Zeiss, Jena, Germany).