48 A MANUAL OF MOSSES 



Order III. BRYALBS. True Mosses. 



This order comprises numerous mosses of various habit: 

 the endothecium gives rise to the sporogenous tissue, which 

 surrounds an inner sterile tissue, loose in Archidium, but form- 

 ing the columella in the rest of the Bryales; the spore-sac is 

 separated from the wall of the capsule by a more or less high- 

 ly developed air-cavity ; there is no pseudopodium but there is 

 a more or less elongated true seta; the outer wall of the 

 archegonium after some growth is ruptured, thus forming a 

 basal vaginule and an apical calyptra; capsule cleistocarpous 

 or, more usually, with a definite operculum and then often with 

 a single or double peristome : the order is conveniently divided, 

 according to the position of the sporogonium upon the leafy 

 shoot of the gametophyte, into the acrocarpous mosses (sporo- 

 gonium at the apex of the leafy shoot) and pleurocarpous 

 mosses (sporogonium lateral upon the leafy shoot). 



Acrocarpi. 



The acrocarpous mosses comprise about thirty families of 

 the Bryales widely distributed and numerous in number of 

 species. For the analytical key to the acrocarpous mosses 

 see the general key to the genera of mosses at the beginning 

 of the book, p. 



Family I. ARCHIDIACBAB. 



Autoicous, sometimes paroicous or synoicous, rarely 

 dioicous : small terrestrial plants, closely gregarious and form- 

 ing broad mats; stems erect, with central strand, below bear- 

 ing rhizoids; leaves of the shoots and also the basal leaves 

 minute, spreading, distant, linear-lanceolate, acuminate, flat, 

 entire, the costa ending in the point; perichsetial leaves much 

 larger, imbricated, more or less linear-acuminate from a 

 lanceloate base ; leaf-cells smooth, prosenchymatous or some- 

 times sub-vermicular to parenchymatous: capsule sessile, 

 spherical, terminal, non-operculate ; columella none; spores 

 commonly 16 — -20, about .200 mm. in diameter. 



One genus only, the characters being as given for the 

 family, comprising about 26 species, distributed widely in the 

 temperate zones. Six species are native in North America, 

 but only one is likely to be collected in our region. 



1. ARCHIDIUM Bridel. 

 1. Archidium ohioense Schimper. 

 Occurs on the ground in meadows and fields throughout 

 eastern United States from New Jersey to Kansas and from 

 Minnesota to Louisiana. Not yet reported in our region, but 

 to be expected, as it occurs in eastern Pennsylvania and in 

 Ohio. 



