130 



minutes and 4 houis. The opeuing of a flower can take place at 

 a greater rate at the beginning than afterwards, or the reverse. 



In consequence of the yellow colour of the petals and of the 

 great number in which the blossoms appear on the bushes, the 

 flowers of P. friiticosa (which in contradistinction to those of Ra- 

 nunculacece are non-lustrous), are visible at a great distance to the 

 insects. Honey is obtained from the nectariferous disk which is 

 enlarged between the calyx and the gynophore. 



As is usually the case in windy locaUties, the number of the 

 species on the ,, älvar ' of Öland which are pollinated only by 

 insects is small. Amongst this little number of species is P. fruti- 

 cosa. The visiting insects that I have observed belong to the fol- 

 lowing groups: 



The humble bee: When the wind happens to be very strong 

 this insect is the most persevering visitor. It seems to prefer the 

 ef -flowers. 



Diptera: Begin their work at sunrise. Are the most industrious 

 visitors af the species. 



Ants: Live in the knolLs of P. fruticosa and rob honey from 

 the flowers. 



The flowers last longer than in the case of P. argentea, anserina 

 and erecta. Those that I have observed have fallen during the 

 course of the fourth day. They are open and without protection, 

 both when it is cloudy, when it rains, and during the night. 



After the flowers have bloomed, the gynophore of the 9-flowers 

 swells, and the sepals bend themselves together around the fruits, 

 which often — as in the case of P. argentea, coUina, reptans and 

 erecta — remain during the whole of the winter. 



In order to lind out the extent to which P. fruticosa bears fruit, 

 I have examined 12 9"SP6cimens with 670 dusters of fruit after 

 a period of fine weather in August 1909, and 24 9-specimens with 

 799 dusters of fruit after a rainy period during the same month 

 in 1910. On the first occasion I obtained 66,4 % impregnated and 

 33,6 % non-impregnated flowers; in the latter case 50,4 % im- 

 pregnated and 49,6 % non-impregnated. 



Thanks to their hairs, the fruits can be spread by means of 

 grazing cattle moving amongst the plants, especially in meadows 

 covered with knoUs. Their spreading can also take place by means 

 of the wind, and sometimes the water, carrying along with it fruits 

 that may have fallen to the ground. This holds good, above all. 



