iv.] STRAWBERRY, AGRIMONY. 99 



and the pistil. They are very much frequented by 

 insects, and as the stamens ripen gradually, and from 

 the outside inwards, there is a considerable interval 

 during which, though the pistil is mature, and some of 

 the anthens are ripe, self-fertilisation is difficult ; while 

 from the great frequency of insect visits, fertilisation is 

 generally effected before the inner anthers are mature. 



In the Strawberry (Fragaria vesca] also, the stigma 

 arrives at maturity some time before the anthers, so 

 that cross-fertilisation generally takes place. The 

 species of Potentilla agree with Fragaria in habit, 

 foliage, and flowers, but the fruit is not succulent 

 The honey, however, is not secreted in drops, but 

 forms a thin layer. According to Van Tieghem, P. 

 tormentilla produces honey abundantly in the north, 

 but scarcely any in the neighbourhood of Paris. Agri- 

 vionia Eupatoria appears to secrete no honey, and is 

 but seldom visited by insects. AlcJiemilla vulgaris is 

 remarkable for variability. The honey is scanty, so 

 that it is little visited by long-lipped insects ; while, 

 from its greenish colour, it is not attractive to beetles, 

 or other colour-loving species. Self-fertilisation is, 

 however, comparatively rare, since the flowers seldom 

 possess both anthers and stigmas ; one or the other 

 being generally more or less rudimentary. This plant, 

 therefore, may be considered to be becoming dioecious. 



The next two genera of Rosaceas, Sanguisorba and 

 Poterium, each of which contains a single British 

 species, have been already alluded to in the opening 

 chapter (ante, p. 10). Sanguisorba (Fig. 10) officinalis 

 is monoecious and fertilised by insects. In Poterium 

 sanguisorba (Fig. 9) some flowers are male, some 

 female, and some hermaphrodite, and the pollen is 



H 2 



