444 The Systematic Value of the New Species. 



VoCHTiNG found that this symmetrical bending was due 

 to gravity. He fixed branches to a chnostat and observed 

 that the flowers opened normally but that the filaments 

 remained straight. Neither light nor darkness had any 

 influence on these processes. The bending of the fila- 

 ments takes place just before, or during the unfolding 

 of the flower. If, about the middle of the day on the 

 evening of which the flower will open, we open a bud 

 we find the filaments perfectly straight.^ 



It follows from this that the degree of bending in 

 the filament depends on the angle which the open flower 

 makes with the perpendicular. The smaller the angle 

 the less the bend. 



In all these respects our species behaves like O. bien- 

 nis. On the other hand in O. miiricata and O. parviflora 

 the filaments are not bent.^ The absence of bending in 

 this case, however, directly depends on the fact that the 

 flowers in these species instead of projecting sideways 

 stand up erect. As a matter of fact, this bending is not 

 entirely absent; I always found some signs of it even if 

 they were only very slight ones. 



§ 27. SYNOPSIS OF THE CHARACTERS OF THE NEW 



SPECIES. 



My new species, without exception, possess the gen- 

 eral characters of the biennis-gvon^ to which 0. La- 

 in arckiana belongs. According to Watson^s Monograph 

 of the genus, the following are the characters of this 

 group. •^' 



^ See the Figure on page 218. 



^ Bull. Soc. Bot France, T. Ill, p. 437. 



^ Sereno Watson, Revision of the Extra-tropical North Amer- 

 tcan Species of the Genus Oenothera, Proc. Amer. Acad, of Arts 

 and Sciences, May, 13, 1873, Vol. VIII, pp. 573-618. 



