264 PLANT LIFE OF ALABAMA. 



the vicinity of Auburn, which were kiudly placed at the service of the 

 writer by the collectors, Profs. F. S. Earle and Carl Baker. 



GENERAL DISTRIBUTION. 



Of the 49 genera known at present to be represented in Alabama, the 

 following are of an exclusively southern range: 



Strigula. ' Glyplris. Gyrostomum. 



Pyrenastrum. Chiodecton. Thelotrema. 



Lecanactis. Heterothecium. 



Trypetbelium. Coenogonium. 



These are most numerously represented by species inhabiting the 

 Louisianian life area, which frequently extend to the neighboring trop- 

 ics and are rarely found north of the Carolinian life area, Represented 

 by a number of species in the southern part of Eastern Forth America 

 and also in the tropics are : 



Graphis. Leptogium. Pyxine. 



Pyrenopsis. Colleraa. 



Omphalaria. Sticta. 



These are also frequently met with in the Alleghenian area. 

 Of decidedly northern distribution are such as 



Vermearia. Rhizocarpon. Placodium. 



The representatives of these genera in the Southern States are mostly 

 confined to the mountain region. Elsewhere they are widely scattered 

 from the cooler temperate to the frigid zones and the cooler regions of 

 the Old World. 



The following are more or less equally distributed throughout the 

 cooler and warmer zones, and many of them have numerous represent- 

 atives in corresponding regions of the Old World : 



Pyreiiula. Riuodina. Cetraria. 



Arthonia. Leptogium. Physma. 



Opegrapha. Collema. Physcia. 



Buellia. Lecanora. Parmelia. 



Biatora. Placodium. Evernia. 



Baeomyces. Heppia. Ramaliua. 



Gyalecta. Pannaria. Usnea. 



Pertusaria. Peltigera. 



Up to the present 198 species and 26 varieties of lichens have been 

 recognized in Alabama. 



REGIONAL DISTRIBUTION. 



Although generally of a witle distribution, the greater number of 

 species and varietal forms of these lowly plants are more or less strictly 

 confined to the several life areas with their floral regions, which share 

 the State. Nearly one-half (48.6 per cent) are confined within the limit 



1 Strigula occurs in Polynesia. 



