192 



BOTANY 



Lichens no trace of an ascogonium has been found, but the fruits 

 arise in a strictly non-sexual manner. 



Classification of Lichens 



The Lichens may be divided into three orders, based upon their 

 affinity with special groups of Fungi. These are : 1. Discolichenes ; 



2. Pyrenolichenes ; 3. 



A Basidiolichenes. About 



two thousand species 

 are known, occurring 

 in all regions. Some, 

 like the Reindeer-moss 

 (Cetraria Islandica) , 

 grow upon the ground 

 in immense quantities, 

 and are of value as 

 food, especially to the 

 Eeindeer. Some of the 

 large fruticose forms, 

 like Usnea barbata, 

 Ramalina reticulata, 

 and the vivid yellow 

 Evernia vulpina (Fig. 

 155, B) of the Sierra 

 Nevada, are very con- 

 spicuous, but most of them are inconspicuous, forming crusts upon 

 exposed surfaces of rocks, trees, fences, etc. 



FIG. lob. A, Ramahna reticulata. (Natural size.) 

 B, Evernia vulpina (X I), a fruticose Lichen show- 

 ing the very large terminal apothecia. C,Cladonia 

 pyxidata, the apothecia borne upon cup-shaped 

 branches or "podetia" (X la). 



BIBLIOGRAPHY 



'01. 1. Atkinson, G. F. Mushrooms, Edible, Poisonous, etc. Ithaca, 1901. 

 '87. 2. De Bary, A. Fungi, Mycetozoa, and Bacteria. Oxford, 1887. 

 '71. 3. Cook, M. C. Handbook of British Fungi. London, 1871. 

 '92-'97. 4. Engler and Prantl. Natiirliche Pflanzenfamilien. 1 TheiL 1 Abt. 



1892-97. (Bibliography of the special groups with each section.) 

 '88-'91. 5. Farlow, W. G., and Seymour, A. B. A Provisional Host-index of 



the Fungi of the United States. Cambridge, Mass., 1888-'91. 

 6. Government publications. Many special papers and bulletins on 



Fungi issued by the Department of Agriculture. 

 '92. 7. Frank, A. B. Lehrbuch der Botanik. Leipzig, 1892. 

 '00. 8. Harper, R. A. Sexual Reproduction in Pyronema confluens and the 



Morphology of the Ascocarp. Ann. of Bot., XIV. 1900. (Includes 



full bibliography of the subject.) 



'89. 9. Hartwig, R. Lehrbuch der Baumkrankheiten. 2d ed. Berlin, 1889. 

 '92. 10. Humphrey, J. E. Monograph of the Saprolegniacese of the United 



States. Mem. Boston Soc. of Nat. History. 1892. 



