170 



species to Gibson, Knox and Posey counties. The species is mainly coastal, 

 occurring along the Atlantic and Gulf coasts, finding its way into the 

 interior along the valley of the Mississippi and its tributaries. The occur- 

 rence of this coastal species, and of others which might be cited, in regions 

 so markedly interior, suggests the thought that they entered our flora at 

 the time when the great northward arm of the Gulf of Mexico practically 

 divided the area of the United States into distinct eastern and western 

 regions. A comparison of the boundaries of this arm of the Gulf of Mexico 

 with the distribution of many species of plants gives striking support to 

 such an explanation. In Indiana, the species is not ordinarily separated 

 from the Burr oak {Qu&rcus macrocarpa Michx., which it closely resembles. 



The Cow or Basket Oak (Quercus Michauxii, Nuttall) so far as our 

 records go occurs only in Knox and Gibson counties, where it is found in 

 low, rich bottom lands. This restriction of area may be due in part to the 

 close resemblance in size and habit of this species to the Swamp White 

 Oak (Quercus oicolor Willdenow) and a consequent failure to distinguish it 

 from that species. This oak, also, is more or less coastal in its mass dis- 

 tribution, finding its way into the interior along the valley of the Missis- 

 sippi; while the Indiana localities represent its northeastern limit the 

 species maintains its normal size and habit. Its ability to maintain a foot- 

 hold in localities often covered with water serves to explain its persistence 

 in the counties named. 



The Spanish Oak (Quercus falcata Michaux) is reported definitely from 

 Knox, Gibson and Posey counties, with an additional citation from Foun- 

 tain County (Brown) which the writer has not had opportunity to verify. 

 Some difficulty arises in this case because of the question of the validity of 

 the species. According to Sargent Quercus falcata is separable into two 

 species, Quercus digitata Sudworth, and Quercus pagodcefolia Ashe. Ac- 

 cording to Gray's Manual 4 Q. falcata is found on dry or sandy soil; upon 

 the authority of Sargent Q. digitata grows in similar soils on dry hills ; 

 while Q. pagodwfolia occurs on rich bottom lands and alluvial banks of 

 streams. In Indiana the form in question "is usually found in low ground, 

 associated with Quercus Mcolor, Q. palustris, Q. Schcneckii, Q. stellata and 

 Q. velulina. The whole of the township is low."^ The habitat as well as 

 considerations of distribution would seem to indicate the species to be 

 Q. pagodwfolia Ashe instead of Q. falcata Michaux. In the Proceedings of 



4 Gray's New Manual of Botany. Seventh Edition, p. 343. 

 5 Deam. Op. cit. 207. 



