" ROSACEA 179 



SO greatly differ. In Eosa the carpels are enclosed in 

 the fleshy hollowed floral axis ; in Eubus the carpels 

 become succulent, the convex floral axis being dry ; in 

 Fragaria the large convex receptacle is succulent, while 

 the ripened carpels are hard, and so closely surround, 

 that they are generally regarded as, the seeds ; lastly, 

 in Potentilla there is nothing which in common parlance 

 could be termed a fruit, both receptacle and ripened 

 carpels remaining dry. 



F. vesca (Strawberry). — The flowers are protogy- 

 nous, with concealed honey. As Darwin has pointed 

 out, the flowers are of three kinds : (l) female, 

 producing much fruit ; (2) complete, which are not 

 so fertile ; and (3) male, which, of course, give none. 

 Schulz has observed gynomoncBcious on the same umbel, 

 and gynodioecious on different umbels, andromonoecious 

 and androdioecious flowers. The flowers are visited by 

 beetles, flies, and bees, but in the absence of insect 

 visits they are capable of self-fertilisation. The Straw- 

 berry is one of the plants in which leaves growing in 

 sunshine and in shade difier considerably. 



In Fragaria and Potentilla the sepals are stipulate ; 

 adjoining stipules unite to form, apparently, a set of 

 leaves alternating with the sepals, thus suggesting a 

 double calyx. 



Potentilla 



Potentilla closely resembles Fragaria, with AYhich 

 perhaps it should be united, but the receptacle is not 

 fleshy. The flowers are generally homogamous, but in 

 P. Comarum protandrous. There are nine British 

 species. 



P. Comarum (Marsh Potentilla). — When the flower 

 opens, the stamens erect themselves and open gradually. 

 Some of the pollen falls on the stigmas, but has no 

 effect, as they are not mature. When the anthers have 

 dropped, the filaments of the stamens curve downwards 

 towards the petals, while the styles, on the contrary, 

 elongate and take their place. The receptacle makes 



