131 



in the case of the plants growing amongst the relatively level slabs 

 of lime-stone. 



WoLFS says. that P. fruticosa belongs to the pala?otypical species 

 which are dying out. But this hardy, plastic and greatly varying 

 species is not threatened with extinction, and most certainly not 

 on the ..alfvar"" of Öland, where there is no possibility of ploughing 



or of the occurrence of forest-lires. 



EXPLAXATIOX OF THE FIGURES. 



Fig. 1. Cracked limestone-slabs in tlie ..alfvar" at Resmo 'Öland. 



In the interstices of the slabs. which are partly filled with 



gravel grows Potentilla fruticosa. 

 Fig. 2. Meadow c o ve red with knolls in the ..alfvar" at Resmo 



poland . On the sloping sides of the knolls grows Potentilla 



fruticosa. Between the knolls lie pools of rainwater. 

 Fig. 3. Potentilla fruticosa from liraestone-slab covered with gravel The 



stem is raore than V 2 metre (59 inches long. trailing along 



the surface of the ground. 

 Fig. 4. Potentilla fruticosa: 3^-flower. The pistils are altogether want- 



ing. 

 Fig. 5. Potentilla fruticosa: ^-flowers. a: The stamens are sterile but 



large and difterentiated as regards filaraents and anthers. b: The 



stamens are sterile and small. The former kind af 'Q-flowers 



is more comraon than the latter. 

 Fig. 6. Potentilla fruticosa: Graphic representation of the variation in 



size of the ^- and ^-flowers. The horizontal row of figures 



represents the diameter of the flowers in mm.: the vertical row 



of figures represents the number af the flowers. ef ^ . 



Fig. 7. Potentilla fruticosa: Graphic representation of the classing of 

 the ^- and ^-if^dividuals according to the average size of their 

 flowers. The horizontal row of figures represents the average 

 size of the flowers per individual and in mm.; the vertical 

 row of figures represents the number of the individuals. ef = 



Fig. 8. a: Diagram of a typical Potentilla-flower. b: Diagram of a 

 flower of Fruticoste and Rupestres. yf. exteriör sepals. f. interiör 

 sepals, kr. petals. st. stamens, fr. gynophore 



