3. Data from cross + sm + x pl sm py
Pl + py

Py plants py plants
0:
1:
pl sm:
Pl sm:
150
17
Pl + :
pl + :
131
37
2:
1-2:
Pl + :
pl + :
26
0
 

From Py plants only - Pl-sm = 17 = 8.8%
193
             
    sm-py = 26 = 13.5%
193
             
From all plants - Pl-py = 80 = 22.2%
361

Order is therefore Pl-sm-py.