129 



3) The normal symmetrical circle of the flowers can become 

 elliptical. 



4) A deviation which, in the case of the Öland-specimens. be- 

 comes a rule is the reduction of the number of stamens. 

 As is Avell known, the number of stamens of the Potentilla-tlov^eT 

 is usually 20, arranged in 3 circles il0 + 5 + 5), sometimes 25 — 30. 

 sometimes 15 — 10. In the groups Fruticos» and Rupestres, the 

 stamens, according to Wolf ipage 25^ are 25 to 30 in number, sit- 

 ting on the thickened edges of the 5 — sided receptacle, and thus 

 not arranged in 3 circles (see fig. 4 and 8). In the case of the 

 Öland P. fniticosa, however, the stamens are seldom 25, and sel- 

 dom more, but usually fewer. On an examination of 108 flowers 

 of the type er" 3, the lowest number of stamens proved to be 15 

 and the average number 22.21. The reduction always takes place in 

 the case of the larger stamens just opposite the sepals: usually, too, 

 in the case of those which are nearest to these stamens at the side. 

 but. on the contrary. as good as never in the case of those stamens 

 standing at the base of the petals. 



ö) I have also observed tetramerous and hexamerous flowers 

 The variation in the numerical ground-plan did not affect the sta- 

 mens, however, when it was a case of the ordinary reduction. 



Individuals with flowers varying in someone or more of these 

 ways. are common. As a rule. such flowers appeared alone 

 amongst the normal ones on the bushes. though they were some- 

 times found in greater numbers. 



The flowers blow, as a rule. in the morning. but. at any time 

 of the day, and even in the evening. flowers can be observed which 

 are beginning to open In this latter case. the opening of the 

 flower is interrupted in order to be continued the following morning. 



The stamens, which. in the bud. are closely pressed together 

 and have their filaments bent, straighten themselves when the 

 flower opens and gradually point more outwards, in which pro- 

 cess the outer stamens are always somewhat before the inner ones- 

 The filaments in the young bud are of the same length as the 

 anthers. and in the open flower they are from 2 — 5 times that 

 length. Even before the flower is fully open. the anthers of the 

 outer stamen open themselves. 



The time that the flower requires for opening varies between 30 



Svensk Botanisk Tidskrift 1911. 9 



