98 HOW TO KNOW THE MOSSES 



Operculum conical or short-beaked, not easily seen. 

 Range, throughout North America; Europe; Asia; Africa. 



The leaves of Fissldens differ from those of other 

 mosses in having a double part that clasps the stem. 

 In the larger plants it can usually be seen with the un- 

 aided eye when the plants are held to the light. It is 

 the lower part of the upper side of the leaf and will look 

 thicker and darker than the rest of the leaf. 



The conspicuous characteristic of Fissidens is the 

 flattened appearance of the plants, due to the leaves ar- 

 ranged in only two rows, one on either side of the stem. 

 Only one other moss described in this book has this 

 arrangement of leaves, Distichium (p. ^2)) 5 but there 

 are several that have a flattened appearance, and the 

 leaves must be examined closely to notice that they are 

 really in more than two rows; sometimes they dis- 

 tinctly show that there is more than one layer. See 

 Mnium (p. 138) and Aulacomnium heterostichum (p. 

 140). Among the pleurocarpous mosses the flattened 

 appearance is more common, but the manner of growth 

 and the branching is very different from that of Fissi- 

 dens. See especially Neckera (p. 185) and Homalia 



(p. 186). 



Fissidens more closely resembles some of the leafy 

 hepatics than any of the mosses. Both the hepatics 

 and Fissidens grow on rocks and moist banks, espe- 

 cially along streams, and it is often necessary to gather 

 the plants and carefully examine them to tell them 

 apart. The leaves of Fissidens lie flat when moist, are 



