Geographical Botany of the United States. 



17 



The observation just made, brings me to the consideration of 

 another point of much interest to the planto-geographer ; and it is, 

 that the Southern Atlantic States, and the more northern and wes- 

 tern sections of the United States, have many common species and 

 genera which are not found elsewhere ; and this too, as I hope 

 hereafter to show, is entirely independent of any great similarity of 



This appears to be more particularly applicable to the natural 

 families, Composite, Leguminosac, and Euphorbiacea?. Of the 

 former we may enumerate the following genera, viz. Chrysocoma, 

 Hemenopappus, Eclipta, Galardia and Silphium. Of the Legu- 

 mmostt-Psoralea, Indigo/era, Petalostemon, Dalea, Amorpha and 

 Schrankia. Of the Euphorbiaceae, we may enumerate Styllingia 9 

 Croton and Jatropha. These genera have scarcely a single repre- 

 sentative in that portion of the Northern States which is east of 

 the Alleghanies. Their northern limit on the Atlantic is the 34th or 

 35th° N. L. but they are found westward, on the banks of the 

 Mississippi, the Arkansa, the Platte, and the Missouri, in some 

 cases, as far north as the latitude of 41°. To this catalogue I 

 might add the Reed or Cane, Miegia macrosperma, Pers. which 

 to the east is confined to East Florida and the lower part of Geor- 

 gia, but at the west is found on all the streams, as far as the 

 Platte — In other cases, particular species of genera, which are 

 widely distributed, follow the same law— Of this number are Ver- 

 bena stricta, L. and V. aubletia, Lin. Coreopsis crassifoliaj Ait. 

 Scutellaria cordifolia, and others. 



But there are also striking peculiarities in the vegetation of the 

 different sections of the United States, which should not pass un- 

 noticed. To the Southern Atlantic region belongs the splendid 

 Magnolia grandiflora, the beautiful yellow Jessamine, Gelsemi- 

 num nitidum ; several species of Styrax, Marshallia, Erianthus 9 

 and Chamcerops; the Sabal pumila, (false palm;) Oka ameri- 

 cana 9 (American olive;) Ixia celestina, Pursh, Heliotropium in- 

 dicum and europeum; Jussiuea grandiflora ; CHococca racemosa ; 

 Pinkneya pubescens, &c. &c. 



The botanist will at once observe in this region, the out-crops, if 

 I may so term it, of a tropical vegetation ; and we find the same, or 

 closely allied, species, in South America and in the West India Isl- 

 ands. Hence the richness of its foliage and its flowers, and the 

 greater number of species found here. In the latter respect, the 



