CHAP. V. HETEROSTYLED TRIMORPHIC PLANTS. 211 



any degree sterile. On the other hand, the illegiti- 

 mate unions between plants of the same form always 

 yield very few seeds, and their seedlings are very 

 sterile. Long -styled parent-plants when fertilised 

 with pollen from their own-form shortest stamens, ap- 

 pear to be rather more sterile than when fertilised with 

 their own-form mid-length stamens ; and the seedlings 

 from the former union were much more sterile than 

 those from the latter union. In opposition to this re- 

 lationship, short-styled plants illegitimately fertilised 

 with pollen from the mid-length stamens of the long- 

 styled form (Class V.) are very sterile ; whereas some 

 of the offspring raised from this union were far from 

 being highly sterile. It may be added that there is a 

 tolerably close parallelism in all the classes between 

 the degree of sterility of the plants and their dwarfed 

 stature. As previously stated, an illegitimate plant 

 fertilised witlr pollen from a legitimate plant has its 

 fertility slightly increased. The importance of the 

 several foregoing conclusions will be apparent at the 

 close of this chapter, when the illegitimate unions be- 

 tween the forms of the same species and their illegiti- 

 mate offspring, are compared with the hybrid unions 

 of distinct species and their hybrid offspring. 



OXALIS. 



No one has compared the legitimate and illegiti- 

 mate offspring of any trimorphic species in this genus. 

 Hildebrand sowed illegitimately fertilised seeds of 

 Oxalis Valdiviana* but they did not germinate ; and 

 this fact, as he remarks, supports my view that au 

 illegitimate union resembles a hybrid one between 



' Dot. Zcitung,' 1871, p. 433, foctnute. 



