VI.] WA TER PLANTS GENERALL V GLABROUS. 127 



even an ant could not force its way in : twenty are 

 aquatic, and hence more or less protected from the 

 visits of ants and other creeping insects; thus we 

 shall frequently find that if, in a generally hairy 

 genus, one or more species are aquatic, they are also 

 glabrous — as, for instance, Viola palustris, Veronica 

 anagallis, V. beccabunga, and Ranunculus aquatilis. 

 Polygonum amphibium is peculiarly interesting, 

 because, as Kerner has pointed out, aquatic speci- 

 mens are glabrous ; while in those living on land the 

 base of the leaf produces hairs. Half a dozen are 

 early spring plants which flower before the ants are 

 roused from their winter sleep ; about the same 

 number are minute ground plants to which hairs 

 could be no protection; three or four are night 

 flowers ; there still remain a few to be accounted for, 

 which would have to be considered individually, but 

 probably the evidence is sufficiently complete to 

 justify the general inference. 



Lastly, I must not omit to mention the hairs which 

 have a glandular character. 



The next point to which I would call attention is 

 the remarkable manner in which certain forms repeat 

 themselves. In some cases, there seems much reason 

 to suppose that one plant derives a substantial ad- 

 va.ntage from resembling another. For instance, 

 Chrysanthemum inodorum, the scentless Mayweed, 

 very closely resembles the Chamomile in leaves, 

 flowers, and general habit. The latter species, how- 

 ever, has a strong, bitter taste, which probably serves 

 as a protection to it, and of which also, perhaps, the 

 scentless Mayweed may share the advantage. These 



