2.3.5. Pollen germinabilityThe SEM observation showed that many separated pollen grainscould germinate normally on the stigma at 8 h after artificial pol-lination (Fig. 7A). However, the pollen massula remained on theintact status (Fig. 7B). The tetrahedral pollen-tetrads could also ger-minate as single pollen grains (Fig. 7C–D), but only one pollen tubegrew normally from one of four tightly packed grains and pene-trated into the stigma (Fig. 7D).