阔叶杨桐衍生胎座的发育特征( 五列木科).

In order to reveal the developmental process of the deuterogenic placenta of Adinandra latifolia from the family Pentaphylacaceae, and the relationship between deuterogenic placenta, carpellary placenta and free central placenta, the flower buds and mature fruits of A. latifolia were observed in detail by scanning electron microscope(SEM)and stereoscopic microscope. Floral buds at different stages of development were collected and fixed in formalin-aceticacid-alcohol, and then dehydrated through an ethanol/amylacetate series, critical point dried with CO2, Au/Pt sputter coated, prepared samples were examined with SEM. Mature fruits were dissected under a stereoscopic microscope directly without preparation. The results showed that during the floral development, 5 carpel primordia were growth rapidly after the stamens initiation, and then ovary was combined with the axial placenta on the upper part and cavity on the bottom part. After the placenta grew on the carpels(named carpellary placenta), several mounds appear at the top of the receptacle within the position opposite to the carpel in the lower cavity. The mounds combined gradually into a hemispherical deuterogenic placentation. And some fertile ovules appeared on the surface of both the carpellary placenta and deuterogenic placenta. Finally, in mature fruits the fertile ovules turn to seeds on both types of placenta in which vascular bundles are discrete. Therefore, deuterogenic placenta appeared independently and was later than the carpellary placenta. The development of deuterogenic placenta in A. latifolia was different from that of the free central placenta in both Caryophyllaceae and Phytolaccaceae(the axial placenta turned into a free central placenta by the septa disappear), but it is basically identical to that of Primulaceae, Theophrastaceae, Maesaceae, Myrsinaceae from Ericales(the free central placenta formed on top of the receptacle directly). [ABSTRACT FROM AUTHOR]