On the Spore and Embryo Sac Formation with Special Reference to the Sterility of Iris japonica THUNB

Abstract

1. In Iris japonica, an allotriploid plant, 13.2% of the ovules had each an embryo sac with normal structure, in 39.2% the embryo sac showed. incomplete development, and 32.2% had abnormal, embryo sacs (Table 2), therefore at least 86.8% of ovules were sterile.
2. 63.4% of the pollen grains were found to be viable (Table 3).
3. There were observed some ovules having two or three megaspore mother cells (Table 1). These mother cells were situated either side by side or end to end in the nucellus. The processes of the development of the embryo sac suggest that they are probably unable to develop into twin or polyembryo.