g8 THE PLANT WORLD. 



study and may be examined directly in water; permanent preparations 

 are most easily preserved in glycerine or in glycerine-jelly, and the 

 plants are often much clearer in these media than they are in water. 

 In studying the leafy forms, it will be found impossible to tear off the 

 leaves at their insertion, as may often be done with the mosses. If this 

 is attempted, the leaves will be sure to tear across irregularly. It be- 

 comes necessary, therefore, to dissect them off carefully under the 

 dissecting-microscope with fine scalpel -needles, or else to examine 

 them while still attached to the stem. When the leaves are not 

 crowded, this can be done directly; when they are crowded, the stem 

 may readily be cut (under the dissecting-microscope) into short sec- 

 tions, each bearing only one or two leaves. 



The leafy hepaticse are most numerous in damp, shaded localities, 

 such as ravines, where they prefer rocks, banks and rotten logs. More 

 detailed notes regarding their habitats will be given under the differ- 

 ent types described. 



I. JUNGERMANNIA BARBATA SCHREB. 



In the mountains of New England and New York and in our north- 

 ern regions generally, Jungerinaiinia barbata is one of the commonest 

 of all hepaticffi, but toward the south it becomes much rarer and soon 

 disappears altogether. Like many of our other northern species, it is 

 widely distributed, occurring in both Europe and Siberia. As a habi- 

 tat it prefers damp, shaded rocks, but it may be looked for also on rot- 

 ten logs and on banks. It is a rather large species, the robust stems 

 being sometimes 3*=*"- or more long and, with the leaves, 2™™- wide. 

 The simple or sparingly forked stems and the flat leaves with their 

 curious teeth usually enable us to distinguish the species at a glance 

 from all the other large species which grow in similar localities, except 

 certain of its immediate allies. /. barbata may be looked upon as 

 the type of a specialized group of Jungermanniae, which the older 

 botanists regarded as a single, very variable species; the botanists of 

 the present day, however, find here rather a half dozen closely allied 

 species, certain of which are still connected by transitional forms. 

 If it happens, therefore, that specimens are found which agree pretty 

 closely but still not exactly with the description given below, they are 

 probably referable to one of these related species. In studying our first 

 hepatic, attention will be directed mainly to the vegetative character- 

 istics of the plant. The reproductive bodies, which are all very uni- 

 form among the foliose species, will be considered at a later time, and 

 in other plants, 



Juugermannia barbata usually grows in flat tufts of considerable 

 extent, the stems being closely appressed to the substratum ; in rarer 

 cases, the stems are ascending or even erect and the tufts become 



