212 



APPENDIX. 



Percentages and Distribution of the Non-endemic Genera of 

 Phanerogamic Plants. 



Extending to other parts 



of America 1594* 88*9 per cent, of 1794, total number. 



Eestricted to America . . 858 53'7 per cent, of 1596, total non-endemic. 



Extending to Old World 



and Pacific Islands . . 738* 46'3 „ „ „ » 



1596 100-0 



Genera numerous in Species. 

 Although we have no genera so numerous in species as Mesembryanthemum (about 

 300 species) and Erica (about 500 species) in South Africa, and Acacia (320 species) in 

 Australia, yet a relatively small number of genera contribute a large proportion of the 

 species. How far the vegetation is composed of these genera is an entirely distinct 

 question, and one not so easily answered, because we have little information respecting 

 the degree of commonness of a great majority of the species. It is well known that 

 pines, oaks, ferns, and various other plants grow gregariously and characterize so many 

 different regions ; and certain species, as we learn from the narratives of various 

 travellers, are exceedingly common in certain localities. Some idea, too, of the pre- 

 vailing species may be obtained from their frequency in the collections from distant 

 districts ; but we know next to nothing of the degree of rarity of the rarer species. These 

 observations are intended to warn the reader against the assumption that the accom- 

 panying list of large genera was drawn up specially to give an idea of the composition 

 of the vegetation. It may be examined, however, both in relation to numerical 

 preponderance of species of a few generic types and their degree of domination in the 

 composition of the vegetation. 



Genera containing Twenty-five Species and upwards. 





Number. 



Endemic. 





Number. 



Endemic 



Mamillaria . 



... 240 



224 



Brought forward . 



1178 



1020 



Epidendrum . 



... 182 



154 



Polypodium . . . . 



109 



44 



Eupatorium 



... 149 



132 



Solanum 



101 



69 



Salvia . 



... 134 



116 



Dalea 



98 



69 



Piper . . 



. . . . 126 



121 



Senecio .... 



98 



93 



Agave . . 



... 126 



104 



Ipomoea .... 



88 



81 



Euphorbia 



. . . . Ill 



74 



Peperomia . . . 



87 



63 



Echinocactus 



. . . . 110 



95 



Quercus .... 



86 



46 



Carried f 



orward . 1178 



1020 



Carried forward 



. 1845 



1485 



* Two of the Old-World genera, Erblichia and Abelia, are only known to inhabit America within our 

 limits ; therefore 11-0, 88-9 and -1 = 100. 



