114 MOSSES WITH A HAND-LENS 



Family 19. HypnacEAE. The Hypnum Family. 



HE preceding species belongs to the great Hypnum 

 Family, which contains a vast number of our common 

 mosses. The majority of the members of this family 

 are slender and prostrate, or creeping with ascending 

 branches. The sporophyte varies a good deal, but the 

 capsulgs are more or less unsymmetric and cernuous in most 

 species. The members of this family usually grow in dense thin 

 mats on soil, stones, rotten wood, and bark of trees. There are 

 hundreds of species belonging to this family and the number with- 

 in out own range is very large. Many of the species and even 

 genera are so closely related and are distinguished by so few and 

 so minute differences that no one but a trained and expert student 

 of mosses can name them correctly. For this reason only a few 

 of the most strongly marked species can be treated here. This 

 is to be regretted, for many of the commonest mosses will thus 

 be omitted and the student will be discouraged by finding so 

 many things that he cannot identify. It is safe advice to the be- 

 ginner to leave the Hypnums until he has studied the more 

 easily recognized mosses. 



Roughly, the more common genera are distinguished thus: 

 Plagiothecium and Entodon are flattened in a plane parallel to 

 the substratum, but the capsules of Entodon are erect and sym- 

 metric, while those of Plagiothecium are curved and cernuous. 

 Brachythecium has very short ovoidal capsules that are cernuous 

 and somewhat curved (except B. acuminatum and B. oxycla- 

 don); the leaves have a strong midrib. Burhynchium, Cirriphyl- 

 Iitin, and Rhynchostegium, have the strong midrib and short 

 capsules of Brachythecium, but the opercula are grotesquely long- 

 beaked, much as in Dicranum. Raphidostegium has long-beaked 

 capsules like the three genera mentioned above, but the leaves 

 lack the midrib. Pylaisia grows exclusively on the bark of 

 trees, and is dark green ; the short branches are strongly curved 

 at the end when dry, and the capsules are erect and symmetric. 

 Hypnum has so many varying forms that 0}\t can best get an idea 

 of it from studying the individual species described below. 



Nearly all the genera of the family were formerly included 

 in the genus Hypnum and the appearance of the species through- 

 out the family has such a similarity that Hypnum can appropri- 

 ately be used for the common name of many species scientifically 



