26 THE COLOURS OF FLOWERS. 



v/ithout any specialisation of form, or any peculiar 

 adaptation to insect visitors. Now, among the poten- 

 tilla group, nearly all the blossoms have yellow petals, 

 and also the filaments of the stamens yellow, as is 

 likewise the case with the other early allied forms, 

 such as agrimony {Agriinonia Eiipatorid) and herb- 

 bennet {Getim tirbafuiift). Among our common yellow 

 species are Potentilla reptans (cinquefoil), P. tonnai- 

 tilia, P. argentea, P. verna, P. fi'uticosa, and P. anse- 

 rina. Almost the only white potentillas in England 

 are the barren ;strawberry {P . fragariastriivi) and the 

 true strawberry [Fragaria vesca), which have, in many 

 ways, diverged more than any other species from the 

 norma of the race. Water-avens {Geiun rivale), how- 

 ever, a close relative of herb-ben net, has a dusky 

 purplish tinge; and Sir John Lubbock notes that it 

 secretes honey, and is far oftener visited by insects 

 than its kinsman. The bramble tribe (Rtibece), including 

 the blackberry (Fig. 6), raspberry, and dewberry, have 

 much larger flowers than the potentillas, and are very 

 greatly frequented by winged visitors. Their petals 

 are usually pure white, often with a pinky tinge, 

 especially on big, well-grown blossoms. But there is 

 one low, little-developed member of the blackberry 

 group, the Rubus saxatiiis, or stone-bramble, with 

 narrow, inconspicuous petals of a greenish-yellow, 

 merging into dirty white ; and this humble form seems 

 to preserve for us the transitional stage from the yellow 

 potentilla to the true white brambles. One step 

 higher, the cherries and apples (though genetically 

 unconnected), have very large and expanded petals, 

 white toward the centre, but blushing at the edges into 

 rosy pink or bright red (Fig. 7). We shall see hereafter 



