236 THE AMPHIBIOUS QUILLWORTS. 



Eaton s Quillwort. 



In 1867 Engelmann described a gigantic species of 

 quillwort from eastern America, which he considered a 

 form of Isoctcs Engelmanni and to which he gave the 

 name of Isoctcs Engelmanni valida. It is described as 

 having from fifty to two hundred leaves two feet or more 

 long, springing from a very massive trunk, and is in fact 

 the largest form of Isoctcs in America, if not in the 

 world. It has never been reported from New England, 

 but within recent years there has been discovered in that 

 region an equally large quillwort which has been named 

 Isoctcs Eatoni. These forms are so nearly alike as to 

 suggest that they are two forms of the same species. If 

 valida is really different from Eatoni and a mere form 

 of Isoetcs Engelmanni, it is not easily explained why it 

 does not occur in New England, where the species is so 

 common. The fact that Isoctcs Eatoni 

 is confined to New England seems to 

 indicate that this is the New England 

 counterpart of valida. When the New 

 England form was discovered it was con- 

 sidered a distinct species, and in this 

 opinion the author concurs. As a species, 

 however, it should be known as Isoctcs valida, since this 

 varietal name was given before that of Isoctcs Eatoni. 



The trunk of this form is occasionally four inches in 

 diameter, and the leaves have been known to reach a 

 length of twenty-eight inches. The summer leaves are 

 usually much shorter, often under six inches long. The 

 peripheral bast bundles are usually present, though weak, 

 and there are abundant stomata. The sporangia are re- 

 markably large, frequently half an inch long, but the 



