1915.] NATURAL SCIENCES OF PHILADELPHIA. 423 



plants in Hall's Yosemite Flora, we get, omitting the grasses, 

 sedges, rushes and varietal forms, a total of 741 species and 311 genera 

 ^^^th a generic coefficient of 41.9 per cent. If the omissions are 

 supplied, Hall estimates that there would be not less than 1200 

 species in the park area of 1124 square miles. 



The selection of regions of greater physiographic diversity, than 

 those which we have discussed, brings out some interesting facts. 

 It shows that our study is a comparative one, as we have contrasted 

 areas such as Point Pelee and the Florida Keys with regions of 

 somewhat greater diversity, such as Jackson County, Missouri and 

 the Yosemite National Park, California. A greater contrast is seen 

 when we compare the Yosemite region of considerable diversifica- 

 tion of topography Avith regions of even greater natural environ- 

 mental conditions. 



The flora of the State of Connecticut,^- which has a great variety 

 of soils, slope exposures, river systems and tidal estuaries, includes 

 621 genera and 1942 species, so that the generic coefficient is 31.9 

 per cent. As a close approximation to this coefficient yielded by a 

 flora at about the same latitude and not far removed geographically, 

 we have the flora of the vicinity of New York. In his monograph, 

 Taylor^^ lists 830 genera and 2651 species of plants. The physi- 

 ography of the New York region includes salt marshes, estuaries, 

 sea beaches, large river systems, mountains, as the Catskills and 

 the Poconos, sandy country, as the pine-barrens of New Jersey, and 

 morainic deposits in Long Island and elsewhere. Hence we find 

 the percentage 31.3 per cent, to be an expression of that diversity. 



The flora of a great state like Pennsylvania,'^ with all kinds of 

 soils, river systems, lakes, bogs, mountain systems and plateaus, 

 might be expected to give a low generic coefficient, and we find on 

 counting that there are 680 genera and 2275 species of ferns and 

 seed plants, so that the coefficient is 29.8 per cent. 



Consulting the Flora of Tennessee, by Gattinger, published in 

 1901, we find that for that state, with a high and ancient system of 

 mountains in its eastern end, that there are 755 genera and 2218 

 species of plants, a considerable number less than in Pennsylvania, 

 and that the generic coefficient of the Tennessee flora is 34 per cent. 



The plant life of Alabama'^ as concerns the pteridophytes and 



12 Committee Conn. Bot. Soc. Catalogue of the Flowering Plants and Ferns 

 of Connecticut, 1910. 



'2 Taylor, Norman: Flora of the Vicinity of New York, 1915. 



'* Small, John K.: Flora of Pennsylvania, by Thomas C. Porter, 1903. 



'5 Mohr, Charles: Plant Life of Alabama, 1901. 



