44 Flowers and their Unbidden Guests. 



water encircling the stem at the base of each inter- 

 node. 



We must here notice that wingless insects scarcely 

 hegin to be really active till most of the dew has 

 evaporated. In vain should we seek for ants on a 

 grass-plot while stiU. dripping with dew. Such flowers 

 as are only open in the morning^ are thus at once 

 insured against the visits of creeping insects, and need 

 no further means of protection. 



We have seen that when the stem of a plant is 

 encircled by water collected at the basis of the leaves, 

 its flowers are protected from unwelcome guests. How 

 much more perfect then must the protection be when 

 the plants actually grow in water ! Alisma, Butomus, 

 Sagittaria, Hottonia, Utricularia, Villarsia, Nuphar, 

 Nymphsea, Hydrocharis, Stratiotes could not be better 

 protected against creeping insects in search of nectar 

 or pollen, than they are by having their pedicles and 

 peduncles floating in the water or rising out of it, so 

 that their flowers stand either above or upon the surface 

 of the water. It is worthy of remark that these 

 water-plants are one and all without any other protective 

 appliances, and that such are only developed should 

 the isolating piece of water chance from any cause to 

 disappear. From this point of view, the case of 'Poly- 

 gonwm amphibiv/m L. is very instructive. The beau- 



^ For instance Lapsana communis and Grepis pulelira have their 

 flowers open only from 5.30 a.m. to 9 or 9.30 A.M. 



