8 TRANSACTIONS OF WAGNER 



VEGETATION OF SOUTH FLORIDA 



phytogeographers* upon the coefficient of community. The ratio of the 

 number of species common to two districts to the total number of species in the 

 two districts taken together is their coefficient of community. This is derived 

 as follows: 



.-, . . , .. Number of species common to 2 districts 



Coefficient of Community = X i oo 



Total number of species in the 2 districts 



Adding then the total number of species in the Flora of Miami (878) and the total 

 number in the Flora of the Florida Keys (627), we have as the denominator, 

 1505, the total number of species in the two districts. The total number of 

 species common to the Miami region and the Florida keys is 282, as obtained 

 from Small's Flora of Miami. Hence, we have 7X100= 18.73 % 



The coefficient of community for the two districts in South Florida is 

 18.73 P er cent. Thus in spite of their proximity and the somewhat similar 

 ecologic conditions, the flora of our two districts possess very different com- 

 positions. 



ECOLOGIC ANALYSIS 



Growth Forms. In the classification of growth forms, I have chosen the 

 system of Raunkiaer,f because, in spite of its one-sidedness it emphasizes one 

 of the most important features of plant life, and because it is easier to handle 

 than other classifications of growth forms, and it is possible to express statistic 

 data in comparison with other regions. The biologic types (growth forms) of 

 Raunkiaer are arranged according to the way in which plants live through the 

 unfavorable seasons of the year, and emphasis is put upon the degree and the 

 kind of protection afforded to the dormant buds. In countries where the con- 

 ditions are favorable, the dominant plants are phanerophytes (Ph.), their buds 

 being found on aerial branches. This group includes trees and shrubs. Ac- 

 cording to the height of the phanerophytes, Raunkiasr divides them into 

 mega-, meso-, mikro-, and nanophanerophytes. The chamaephytes (Ch.) are 

 those plants with dormant buds on the surface of the ground, or just above 

 it. In the former case, they are plants with superficial, creeping and persistent 

 shoots; in the latter case, they are cushion-plants, or undershrubs. The 

 hemicryptophytes (H.) have dormant buds found in the upper soil layer, just 

 below the surface, while their aerial shoots are not perennial. The fourth 



*Jaccard, Paul: The Distribution of the Flora in the Alpine Zone. The new Phytologist, xi: 

 39, Feb., 1912. 



f Raunkiter, C.: Types biologiques pour la geographic botanique. Bull. Ac. Roy Sc. Dane- 

 mark, 1905; Statistik der Lebensformen als Grundlage fur die biologische Pflanzengeographie. Beitr. 

 Bot. Centralbl., 27 (1910): i7i-2ood. 



