^syf EXGti.Kt) PJiBBICARtAS. 107 



or very near its edge. Those that grew on the muddy shore can 

 easily be recognized." What makes these so readily recogniza- 

 ble is, of course, their smooth and glossy oblong unpointed 

 foliage on elongated petioles; just the contrast one notices 

 between leayes of aquatic and those of terrestrial growth in these 

 plants. Now these branches and foliage are so precisely aquatic? 

 in aspect, that without my correspondent's word to the con- 

 trary, I should have believed them to belong to some other plant 

 than P. coccinea, which species is not otherwise known to me as 

 having an aquatic state, though in a considerably altered riparian 

 condition it is not rare. Scrutinizing one of the best of these 

 specimens from end to end and leaf by leaf, by aid of a lens, I 

 read its history; and the reading at once verifies my correspond- 

 ent's statements as to what he saw on a certain day, and yet 

 reveals another fact confirming my strong impression that what 

 I had before me was practically an aquatic branch, at least, as 

 to a part of its growth. The specimen is 10 inches long and has 7 

 well developed leaves. The 3 leaves occupying the lower half 

 of the stem have all the marks of the aquatic Persicaria. They 

 are perfectly glabrous beneath, even to the midvein, and they 

 have the long slender petioles usual to floating persicaria foli- 

 age. These 3 leaves of the branch were developed earlier, and 

 manifestly at a higher stage of the water in the pond, so that 

 for the time this branch and its leaves were floating in shallow 

 water. From the middle of the branch it changes from the 

 horizontal in direction, curving upwards, and its leaves lose 

 one by one that peculiar outline which the aquatic ones have, 

 become more and more like the terrestrial leaf -form, and they 

 acquire as gradually the traces of pubescence, even on the mid- 

 vein beneath. Here, then, is clearly written the history of a 

 subsidence of the waters of the pond in the later summer, so 

 that what had been aquatic branches with floating leaves, were 

 found to be riparian in the autumnal season. 



This aquatic foliage of P. coccinea presents some points of 

 clear divergence from that of any other; bat I shall reserve 

 the diagnosis for some future time, hoping, meanwhile, for 9> 



