II R0SACE.5i 175 



fruits which ripen when the leaves are still green to be 

 red, as this gives the greatest contrast. On the other 

 hand, red would not be conspicuous against faded leaves 

 which are brown, or even sometimes themselves reddish. 

 For such fruits, blue or black would be more advan- 

 tageous, and, as a matter of fact, many heath and moor 

 species have bluish or black fruit, as, for instance, the 

 Bilberry, the closely allied Vaccmium uliginosum, or 

 the Black Bearberry. P. Cerasus keeps its leaves 

 longer in Southern Europe, and in Ceylon is evergreen. 

 The fruit of P. Padus (Bird Cherry) is also black. 



Spir^a 



We have two species of this genus : in one, S. 

 Ulmaria, the leaves have a few large segments, and are 

 white underneath ; in the second, S. Filipendula, they 

 have many small segments. 



S. Ulmaria (Meadow-sweet). — The flowers are sweet- 

 scented, yellowish white, homogamous, and honeyless, 

 but a good deal visited by insects for the sake of the 

 pollen. The carpels are twisted, forming a spiral. Can 

 the object be to mimic small caterpillars, and thus 

 inveigle birds to carry them about? The seeds are 

 brown, oblong, and compressed laterally. 



Dryas 



D. octopetala is found in limestone and mountain 

 districts ; it has large flowers with concealed honey. 

 The petals, as the name implies, are eight in number. 

 H. Miiller describes the flowers as protogynous. When 

 the blossom opens the styles are mature ; in a short 

 time the anthers commence to open, beginning with 

 the outer ones, so that at first insects touch the pistil 

 on one side, and the anthers on the other ; thus cross- 

 fertilisation is almost sure to take place. If, however, 

 there are no insect visits, the styles bend outwards 

 toward the inner anthers, and the flower is self-fertilised ; 

 moreover, the flowers gradually bend over, so that the 



