The Plant World 



A MONTHLY JOURNAL OF POPULAR BOTANY. 



Vol. l APRIL, 1898. No. 7. 



STUDIES AMONG OUR COMMON HEPATICy€. 



By Alexander W. Evans. 



INTRODUCTORY. 



UNDER the name Hepaticae, it is customary to group together 

 plants which differ so markedly among themselves that it is 

 difficult, if not impossible, to frame descriptive characters which 

 will apply to all. These differences, which affect both the 

 gametophyte and the sporophyte, are so profound that it is more con- 

 venient to split up the group at once into its three well-marked orders 

 and to consider these separately, rather than to attempt to treat it as 

 a whole. While doing this, however, the interrelationships between 

 the orders must not be overlooked and will be pointed out as our 

 studies advance. 



About nine-tenths of all described species of hepaticae belong to 

 the order Jungermanniales, and characteristic examples of these will 

 be studied first, not only on account of their great preponderance, but 

 because their simplest representatives are the most primitive of all 

 hepaticae, and their most highly developed show, in certain respects, 

 an approach toward the mosses. In the simplest genera, the gameto- 

 phyte is " thallose," that is, it consists of a flattened axis or thalloid 

 shoot without any differentiation into stem and leaves; in the more 

 highly developed, such differentiation is clearly apparent, and the 

 plants are therefore spoken of as leafy or "foliose " hepaticae and also 

 as "scale-mosses." These two extreme conditions are connected by 

 intermediate forms. 



Material of the leafy species may be prepared in much the same 

 way as in the mosses ; it should be freed as far as practicable from the 

 substratum and dried under very little pressure. After the dried 

 material has been soaked in water for a few minutes it is ready for 



