42 



MOSSES WITH A HAND-LENS 



THE WATER-LOVING HYPNUMS 



THERE are several species belonging to the Hypnum Family 

 that grow on the stones in the bed of brooks, particularly 

 in mountain regions. They do not belong to one genus, 

 but their similarity of habitat, often combined with similarity in 

 appearance, makes it easier to study them together. 





Fig. 34. Rhynchostl'gium 7-usciforme X 2 ; leaves and capsule X 10. 



Two of these, the Beaked Water Moss {Rhynchostcgium 

 rusciforme (Neck) B. & S.] and the Round-leaved Hypnum 

 {H. dilatatum Wils. ) grow on stones in the middle of brooks and 

 are partially submerged, or at least wet with spray, during the 

 entire year, and are submerged except at low water. These 

 mosses are very dark, almost black, except the youngest portion 

 of the plants, and the leaves are very broadly ovate to almost 

 orbicular, and obtuse or very bluntly acute. 



The Beaked Water Moss is the coarser of the two, with 

 broadly ovate costate leaves and strongly beaked capsules, which 

 latter mature in September. They are frequently produced in 

 large quantities and present a very pretty appearance indeed 

 against the dark background of the gametophyte. 



The Round-leaved Hypnum belongs to the subgenus Hygro- 

 hypnum. Its leaves are suborbicular and nearly ecostate. The 



