Dec, 1913.] The Classification of Plants, XL 211 



THE CLASSIFICATION OF PLANTS, XL* 



John H. Schaffner. 



The various groups of Bryophyta are apparently closely 

 related and it is sometimes difficult to tell what characters are 

 of phyletic importance. There are no fundamental peculiarities 

 or structures which will divide the group into two or three main 

 di\'isions without considerable overlapping of equally important 

 structures of another type. Thus one is compelled in certain 

 cases to delimit classes and orders on trivial or rather unimportant 

 structures. Nevertheless, the complexity of the group as a whole 

 demands that it should be divided into a number of classes. 



The homologies of the various organs are quite evident among 

 themselves and also when compared with the plants immediately 

 above; yet we often find a very illogical tenninology and a set 

 of names applied to the various structures which makes comparison 

 with other phyla impossible until special explanations have been 

 made. If we apply a morphological tenninology to the mosses 

 and liverworts similar to that used in other groups no difficulty 

 of presentation is experienced. Such an attempt has worked well 

 for the writer in dealing with large numbers of students in general 

 botany. 



The synopsis of the Bryophyta given below segregates the 

 main groups and attempts to arrange them in phyletic series. 



SYNOPSIS OF THE CLASSES OF BRYOPHYTA. 



A. Archegonia not sunken in the plant body ; sporophyte without 

 definite intercallary growth between the foot and sporan- 

 gium. 



I. Gametophyte thalloid or with stem and scales, the scales 



always without a midrib; sporophyte without a stalk or 

 differentiated into foot, stalk and sporangium mostly 

 with elaters, never with a columella, opening irregularly or 

 by a lid, or mostly by four valves. Hepaticae. Liver- 

 worts. 



II. Gametophyte with stem and scales, the scales mostly 



with a midrib; sporophyte usually with a solid stem; 

 sporangium mostly opening by a lid (operculum) or if 

 opening by slits or valves, not with elaters; columella 

 present in the sporangium, complete or occasionally 

 incomplete ; archegonium usually developing as a calyptra 

 after fertilization. 



* Contributed from the Botanical Laboratory of Ohio State University, 

 No. 78. 



