324 HARPER 



Two interesting things are brought out by the above table. 

 The uniformity of the flora is shown by the small number of 

 species; only 739 vascular plants known in 11,000 square miles. 

 There are several states in the Union with a smaller area which 

 contain nearly twice as many species. Second, the comparative 

 newness of the flora is probably correlated with the large pro- 

 portion of monocotyledons, which here constitute 30 per cent, 

 of the total angiosperms. All parts of the coastal plain and 

 glaciated region which have been sufficiently studied seem to 

 have very nearly the same proportion, while in the Metamorphic 

 and Palaeozoic regions the monocotyledons average only about 

 25 per cent. 1 



Among the vascular plants it will be noticed that there are 

 three times as many genera as families, and twice as many 

 species as genera. 



Largest families. The twelve largest families (each of which 

 contains more than 1 . 5 per cent, of the total spermatophytic 

 flora), and the number of native genera and species in each, are 

 as follows: Compositas (including Cichoriaceae) , 45 genera, 88 

 species; Cyperaceae, 12 genera, 79 species; Gramineae, 21 genera, 

 55 species; Leguminosae (including Caesalpiniaceas and Mimo- 

 saceae), 24 genera, 43 species; Scrophulariaceae, 10 genera, 24 

 species ; Ericaceae (including Vacciniacese, Pyrolaceae, and Cleth- 

 raceae), 12 genera, 23 species; Labiatae, 9 genera, 18 species, 

 Cupuliferae, 2 genera, 16 species; Umbelliferae, 7 genera, 14 species; 

 Onagraceas, 4 genera, 13 species; Euphorbiaceae, 7 genera, 12 

 species; Orchidaceae, 5 genera, 11 species. 



The relations of these twelve largest families to the nineteen 

 typical habitats previously described may be summarized as 

 follows. In the table below, the number immediately following 

 each family name indicates the number of native species, and 

 the numbers in the columns the number represented in each 

 habitat. 



The last column, which does not strictly belong to this table, 

 but is added here for convenience, shows the ratio of each 

 family to the total number of spermatophytes. 



1 See Torreya 5: 207-210. 1905. 



