118 TYPE STUDIES 



certain thalloid liverworts ; (2) wet margins of ponds and swamps and wet 

 meadows, sometimes supplying Marchantia abundantly and many mosses ; 

 (3) the surface of small ponds and the mud around their borders occasionally 

 abounding in Riccia and Ricciocarpus ; (4) wet rocks along shaded streams, 

 walls of gorges and entrances to caverns frequently with veiy extensive 

 growths of liverworts, Marchantia, Conocephalus, Pellia, etc.; (5) base and 

 sides of trees in damp, shaded woods, rocks and the ground in similar situa- 

 tions covered with mats of leafy liverworts and mosses, often mixed together 

 in confusion, but some types presenting characteristic habits of growth ; 

 (6) dry earth in more open woods, pastures, bare hillsides, etc. , with a number 

 of characteristic types of mosses but no liverworts. Notes should be taken 

 on the life habits, especially with reference to the texture of the forms in 

 relation to the conditions of moisture. Collections may be made and brought 

 to the laboratory for study. For city classes, abundant growths of Lunularia 

 and Marchantia may frequently be found in greenhouses, especially those 

 not well kept, together with many mosses and their protonemata. 



123. Ricciocarpus. Most species of Riccia may also be studied by this 

 outline. If living material is available, observe carefully the life habits. 



A. General morphology. Note : 



1. The upper and lower surfaces of the thallus. How are they distin- 

 guished ? 



2. The form of the plant, method of branching. 



3. The notched tips or forward ends of the branches where are situated 

 the growing points. How do the plants reproduce vegetatively ? 



4. A shallow furrow, thickened somewhat on the lower side like a 

 midrib, running into each lobe, forking when the thallus forks, and 

 ending in the growing points. 



6. The position of globular bodies, the older ones black, imbedded in 

 the denser tissue along the furrow. These are sporophytes, frequently 

 called the fruit of the liverwort. What is the relative arrangement 

 of the younger and older sporophytes ? 



6. Examine the structure and distribution of membranous /rmgfes and 

 delicate filaments, rhizoids, on the lower surface. Cut off some of 

 these and examine under m.p. What are their functions? Draw. 



Draw a habit sketch of the upper surface, showing points discussed 

 above. 



B. Structure of the thallus. Cut sections in pith across the thallus and 

 through the sporophytes when possible. Note : 



1. The cell structure of the upper and lower surfaces as compared with 

 one another. Where are the chloroplasts chiefly found ? 



2. The position and attachment of the fringes and rhizoids. 



C. Structure of the sporophyte. Study sections of the sporopyhtes with 

 developing or mature spores. Note : 



