委陵菜大孢子的发生和雌配子体的形成

Megasporognesis occurrence and female gametophyte’s formation of Potentilla chinensis Ser.

对委陵菜不同时期花器官解剖结构的观察表明 ,胚珠类型为弯生型 ,厚珠心型 .孢原细胞纵向分裂或斜向分裂 ,形成 2个造孢细胞 ,多数情况下 ,其中一个造孢细胞退化消失 ,另一个发育成大孢子母细胞 .大孢子母细胞进行减数分裂 ,形成三分体 .三分体在珠心中作纵向直线排列 ,珠孔端的细胞是功能大孢子 .功能大孢子发育经过单核胚囊、2核胚囊、4核胚囊、8核胚囊 成熟胚囊属蓼型胚囊 胚囊成熟时 ,3个反足细胞解体遗留痕迹 .

The result obtained from experiments of the dissected structures of flower organs in the different stages of Potentilla chinensis Ser.indicates that its ovule is a campytotropous ovule and crassinucellate ovule.Then only one archesporial cell is included in every ovule.The vertical division or oblique division of the archesporial cell breaks into two sporogenous cells,one of which develops into megasporocytes,cytokinesis in the megasporocytes accompansis meiosis,it does not occur after the homotypic division in the micropylar dyad cell,and micropyle megaspore of a linear of three cells develops into 8 uncleate.The development of embryo sac is of the polygonum type.Three antipodal cells degenerated in the embryo sac when shed.