Distribution of Vexnonia iti the United States. 139, 



ready to germinate in due season if blown to a fit spot. We find 

 now that, leaving out the widely dispersed forms, all the western, 

 species are close allies, while those of the east are also closely related. 

 It would appear that two sections can be formed of the species- 

 of the genus. One of these has ample, generally lancaolete, leaves, 

 and the other has Imear leaves. In the first group there are seven^ 

 and in the second, eight species and varieties. Of the lanceolBte- 

 leaved forms one is strictly southern and eastern ioligophylla) , one 

 is western {Baldivinii), but all the others are general in their distri- 

 bution. But Baldtvinii, the western species, is said to "pass into" 

 altissiina, one of the generally distributed forms, so it may be 

 regarded as a form developed under special conditions. In the 

 linear leaved section, six out of eight are western; one of the others, 

 angustifolia var. scaberrima, extends from South Carolina to Florida, 

 and the other, var. pnmila of the same species, is found in South 

 Florida. 



The first group of ample-leaved forms may be regarded as com- 

 ing from the soutli by way of the West Indies and Florida, spread- 

 ing in several cases far northward and westward, and in others 

 adhering to the Atlantic Coast. The second group, that of linear- 

 leaved forms, probably arrived by way of Mexico, and then spread 

 north and east; in the latter direction partly because of the pre- 

 vailing direction of the wind, partly because of the dryness of the 

 country to the west. Besides the leaves, there is a prominent 

 feature in some species of long filiform tips to the involucral scales. 

 These do not seem to be correlated in any way with the lanceolate 

 or linear leaves, nor with the distribution. The table given below 

 represents the distribution of the two groups of species : 

 Leaves linear : 



Arkansana : Missouri, Kansas to Texas. 



Jamesii : Nebraska and Arkansas to Texas. 



Lettermani: Arkansas and Texas. 



angustifolia : North Carolina to Florida, Arkansas and Texas. 



var. scaberrima South Carolina to Florida. 



var. Texana : Arkansas, Louisiana and Texas. 



var. pumila : Southern Florida. 



Lindheimeri : West Texas. 

 Leaves lanceolate : 



Noveboracensis : General but mostly eastern. 



var. latifolia : Pennsylvania and Ohio to Florida. 



