l66 Rhodora [August 



ever is made by Stephani in his Species Hepaticarum (1900). The 

 studies of Warnstorf,^ however, show conclusively that the plant is 

 worthy of specific rank, and it is now recognized as a distinct spe- 

 cies by Schiffner and by several other European hepaticologists. 

 Many years ago Nees von Esenbeck'" referred to P. Flotowiana a 

 specimen from Newfoundland, in the Montague herbarium. This is 

 apparently the only reference to the species as an American plant, 

 and even this must be considered doubtful since the Newfoundland 

 specimen is not mentioned in any subsequent writings. The species, 

 however, was collected several years ago at Yakutat, Alaska, by 

 Coville and Kearney and has been listed and described by the 

 writer under the name of F. hibermca.^ The latter species has also 

 been recorded from Nebraska, Ontario and British Columbia,* and it 

 is of course possible that some of these reports are based on P. 

 Flotowiana instead of on the true F. hibcrnica. The two species are 

 separated from each other by purely vegetative characters: F. 

 hibernica is less robust than F. Flotowiana, the midrib of the thallus 

 is thinner and passes more abruptly into the delicate marginal wing, 

 and the latter is never crispate but is plane or nearly so. In robust 

 forms of /'. Flotowiana, Tansley and Chick ^ have demonstrated the 

 presence in the midrib of two slender strands of slightly elongated 

 cells with lignified walls, and Pearson's var. leptodesma is based on a 

 peculiarity of this sort. Cavers' has shown that these strands play 

 an important part in the conduction of water, just as the single 

 strand does in F. Lyellii, but he has also shown that they fail to 

 develop in plants cultivated under very moist conditions. It would 

 appear from this that the presence or absence of the strands is not 

 of very great importance from the standpoint of the taxonomist and 

 that it should hardly be used as a differential character in separating 

 Moerckia generically from Fallavicinia. F. Flotowiana is perhaps 

 the most noteworthy of the recent additions to the hepatic flora of 

 New England. 



1 Allgem. Bot. Zeitschr. 1899 : 15. Kryptogamenfl. der Mark Brandenburg, i -. 

 99, 1902. 



2 Naturgeschichte der europ. Lebermoose, 3 : 346. 1838. 



3 Proc. Wash. Acad. 2 : 291. 1900. 



* Webber, Cat. Flora Nebraska, 93. 1S90; Macoun, Cat. Canadian Plants, 7 : 

 8. 1902. 



"Ann. Bot. 15: 7.//. /,/• /• 1901. * The Naturalist, 1903: 45' • 



