ABNOBMALITIES IN OENOTHERA. 177 



anthers are small, with very short filaments, empty and 

 sterile. The style is frequently markedly pubescent almost 

 to the top. It tapers strongly and gradually to the top which 

 is very slender, and the stigma lobes are reduced to four 

 delicate prongs. 



A remarkable peculiarity of all these flowers is the com- 

 plete, or almost complete, suppression of the hypanthium. 

 I have remarked elsewhere (Gates, 1910, footnote, p. 208) 

 that the attacks of a certain insect also lead to suppression 

 of this organ. Its wide variability, which ShuU (1907) has 

 proved statistically, and its suppression under various abnor- 

 mal conditions, as I have shown, are probably significant 

 facts, related to its recent phylogenetic development as sug- 

 gested by MacDougal. A marked feature of this type of 

 virescence is that the flowers do not drop off but remain per- 

 manently attached to the stem. In many cases an elongation 

 occurs below the ovary. This is more slender than the ovary 

 and is hard and woody, tough, and strongly attached to the 

 stem. In the meantime (see plate 30, f. 2, flowers to the left) 

 leaves grow out from the interior of the flower and in this 

 way the flower becomes transformed into a short side branch. 

 The ovary in the meantime almost completely disap- 

 pears, possibly becoming transformed into a portion of 

 the woody branch by an alteration in its structure. 

 This stem is always more slender than was the original ovary. 

 A whole group of young leaves of abnormal shape (long and 

 narrow) may grow out of the flower in this manner. The 

 elongation to form a side branch is sometimes partly above 

 and partly below the ovary, as may be seen from plate 29. It 

 may also be seen from this figure, though not clearly, that 

 the lower flowers on the main stem were normal and have 

 dropped ofif leaving the growing ovaries behind. Some of 

 these afterward developed into large capsules. 



The plant in 1909 which produced only virescent flowers, 

 wilted and died about August 10th for no assignable cause, 

 while the other plants continued to bloom long afterwards. 

 It seemed as though the production of virescent flowers was 

 equivalent to seed production in the physiology of the plant. 



